Cysteine synthesis from O-acetylserine

Reactome:R-MTU-936721

The Mycobacterium tuberculosis O-acetylserine route joins CysH/Sir sulfate reduction with CysE serine acetylation and CysK1-dependent cysteine synthesis. The outdated CysK2 O-acetylserine reaction is excluded: CysK2 uses a distinct O-phosphoserine route. Native thioredoxin and ferredoxin states and PLP-bearing CysK1 are retained. Reactome chemical forms include sulfurous acid, sulfide(2-) and acetic acid; this graph does not claim physiological protonation or complete stoichiometric balance.

Pathway type

biopax pathway

Organism scope

Mycobacterium tuberculosis NCBITaxon:1773

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Pathway network

33 nodes · 69 asserted directed edges

Arrows show recorded subject → object relationships, not necessarily metabolic flow. Select a node for details or an arrow for evidence. Scroll, zoom or find a node to explore.

Reaction / activity
Chemical / cofactor
Protein / complex
Cell / process context
Solid arrow: mechanistic relation
Dashed arrow: membership, location or cofactor relation

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Components and activities

Declared biological components and source reaction directions
Node	Kind or role	Source direction
Mycobacterium tuberculosis `NCBITaxon:1773`	taxon
5'-adenylyl sulfate(2-) `CHEBI:58243`	small molecule
hydron `CHEBI:15378`	small molecule
sulfurous acid `CHEBI:48854`	small molecule
adenosine 5'-monophosphate(2-) `CHEBI:456215`	small molecule
tetra-mu3-sulfido-tetrairon(1+) `CHEBI:33723`	cofactor
water `CHEBI:15377`	small molecule
sulfide(2-) `CHEBI:15138`	small molecule
tetra-mu3-sulfido-tetrairon(2+) `CHEBI:33722`	cofactor
siroheme `CHEBI:28599`	cofactor
acetyl-CoA(4-) `CHEBI:57288`	small molecule
L-serine zwitterion `CHEBI:33384`	small molecule
O-acetyl-L-serine `CHEBI:17981`	small molecule
coenzyme A(4-) `CHEBI:57287`	small molecule
acetic acid `CHEBI:15366`	small molecule
L-cysteine zwitterion `CHEBI:35235`	small molecule
Trx(red.) `Reactome:R-MTU-936674`	protein
TrxA(ox.) `Reactome:R-MTU-1222293`	protein
CysH `Reactome:R-MTU-936694`	protein
Fdx `Reactome:R-MTU-937262`	protein
Sir `Reactome:R-MTU-936705`	protein
CysE `Reactome:R-MTU-936604`	protein
PXLP-K44-CysK1 `Reactome:R-MTU-936587`	protein
CysH holoenzyme `Reactome:R-MTU-936704`	complex
Iron Sulfur Cluster `Reactome:R-ALL-70986`	cofactor
Fdx(red.) `Reactome:R-MTU-937263`	complex
Fdx(ox.) `Reactome:R-MTU-937267`	complex
Sir holoenzyme `Reactome:R-MTU-936607`	complex
CysK1 dimer `Reactome:R-MTU-936755`	complex
cytosol `GO:0005829`	cellular component
sulfite results from reduction of APS `Reactome:R-MTU-936655`	molecular activity	left to right
sulfite is reduced to sulfide `Reactome:R-MTU-936703`	molecular activity	left to right
acetylation of serine `Reactome:R-MTU-936615`	molecular activity	left to right
deacetylation of O-acetylserine and sulfhydrylation using CysK1 `Reactome:R-MTU-936642`	molecular activity	left to right

Mechanistic edges

Mechanistic edges and their cited evidence
Subject	Predicate and description	Object	Evidence
5'-adenylyl sulfate(2-) `CHEBI:58243`	consumes	sulfite results from reduction of APS `Reactome:R-MTU-936655`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction1 places physical entity SmallMolecule1 on its left side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction1/bp:left/#SmallMolecule1; #BiochemicalReaction1/bp:conversionDirection`
Trx(red.) `Reactome:R-MTU-936674`	consumes	sulfite results from reduction of APS `Reactome:R-MTU-936655`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction1 places physical entity Protein1 on its left side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction1/bp:left/#Protein1; #BiochemicalReaction1/bp:conversionDirection`
sulfite results from reduction of APS `Reactome:R-MTU-936655`	produces	hydron `CHEBI:15378`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction1 places physical entity SmallMolecule2 on its right side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction1/bp:right/#SmallMolecule2; #BiochemicalReaction1/bp:conversionDirection`
sulfite results from reduction of APS `Reactome:R-MTU-936655`	produces	TrxA(ox.) `Reactome:R-MTU-1222293`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction1 places physical entity Protein2 on its right side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction1/bp:right/#Protein2; #BiochemicalReaction1/bp:conversionDirection`
sulfite results from reduction of APS `Reactome:R-MTU-936655`	produces	sulfurous acid `CHEBI:48854`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction1 places physical entity SmallMolecule3 on its right side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction1/bp:right/#SmallMolecule3; #BiochemicalReaction1/bp:conversionDirection`
sulfite results from reduction of APS `Reactome:R-MTU-936655`	produces	adenosine 5'-monophosphate(2-) `CHEBI:456215`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction1 places physical entity SmallMolecule4 on its right side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction1/bp:right/#SmallMolecule4; #BiochemicalReaction1/bp:conversionDirection`
sulfite results from reduction of APS `Reactome:R-MTU-936655`	occurs_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: All physical entities on both sides of BioPAX BiochemicalReaction1 have the same cellular location. Source location `#BiochemicalReaction1/bp:left\|bp:right; physicalEntity/bp:cellularLocation/#CellularLocationVocabulary1`
hydron `CHEBI:15378`	consumes	sulfite is reduced to sulfide `Reactome:R-MTU-936703`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction2 places physical entity SmallMolecule2 on its left side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction2/bp:left/#SmallMolecule2; #BiochemicalReaction2/bp:conversionDirection`
sulfurous acid `CHEBI:48854`	consumes	sulfite is reduced to sulfide `Reactome:R-MTU-936703`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction2 places physical entity SmallMolecule3 on its left side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction2/bp:left/#SmallMolecule3; #BiochemicalReaction2/bp:conversionDirection`
Fdx(red.) `Reactome:R-MTU-937263`	consumes	sulfite is reduced to sulfide `Reactome:R-MTU-936703`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction2 places physical entity Complex2 on its left side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction2/bp:left/#Complex2; #BiochemicalReaction2/bp:conversionDirection`
sulfite is reduced to sulfide `Reactome:R-MTU-936703`	produces	water `CHEBI:15377`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction2 places physical entity SmallMolecule6 on its right side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction2/bp:right/#SmallMolecule6; #BiochemicalReaction2/bp:conversionDirection`
sulfite is reduced to sulfide `Reactome:R-MTU-936703`	produces	sulfide(2-) `CHEBI:15138`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction2 places physical entity SmallMolecule7 on its right side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction2/bp:right/#SmallMolecule7; #BiochemicalReaction2/bp:conversionDirection`
sulfite is reduced to sulfide `Reactome:R-MTU-936703`	produces	Fdx(ox.) `Reactome:R-MTU-937267`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction2 places physical entity Complex3 on its right side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction2/bp:right/#Complex3; #BiochemicalReaction2/bp:conversionDirection`
sulfite is reduced to sulfide `Reactome:R-MTU-936703`	occurs_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: All physical entities on both sides of BioPAX BiochemicalReaction2 have the same cellular location. Source location `#BiochemicalReaction2/bp:left\|bp:right; physicalEntity/bp:cellularLocation/#CellularLocationVocabulary1`
acetyl-CoA(4-) `CHEBI:57288`	consumes	acetylation of serine `Reactome:R-MTU-936615`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction3 places physical entity SmallMolecule10 on its left side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction3/bp:left/#SmallMolecule10; #BiochemicalReaction3/bp:conversionDirection`
L-serine zwitterion `CHEBI:33384`	consumes	acetylation of serine `Reactome:R-MTU-936615`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction3 places physical entity SmallMolecule11 on its left side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction3/bp:left/#SmallMolecule11; #BiochemicalReaction3/bp:conversionDirection`
acetylation of serine `Reactome:R-MTU-936615`	produces	O-acetyl-L-serine `CHEBI:17981`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction3 places physical entity SmallMolecule12 on its right side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction3/bp:right/#SmallMolecule12; #BiochemicalReaction3/bp:conversionDirection`
acetylation of serine `Reactome:R-MTU-936615`	produces	coenzyme A(4-) `CHEBI:57287`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction3 places physical entity SmallMolecule13 on its right side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction3/bp:right/#SmallMolecule13; #BiochemicalReaction3/bp:conversionDirection`
acetylation of serine `Reactome:R-MTU-936615`	occurs_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: All physical entities on both sides of BioPAX BiochemicalReaction3 have the same cellular location. Source location `#BiochemicalReaction3/bp:left\|bp:right; physicalEntity/bp:cellularLocation/#CellularLocationVocabulary1`
sulfide(2-) `CHEBI:15138`	consumes	deacetylation of O-acetylserine and sulfhydrylation using CysK1 `Reactome:R-MTU-936642`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction4 places physical entity SmallMolecule7 on its left side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction4/bp:left/#SmallMolecule7; #BiochemicalReaction4/bp:conversionDirection`
O-acetyl-L-serine `CHEBI:17981`	consumes	deacetylation of O-acetylserine and sulfhydrylation using CysK1 `Reactome:R-MTU-936642`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction4 places physical entity SmallMolecule12 on its left side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction4/bp:left/#SmallMolecule12; #BiochemicalReaction4/bp:conversionDirection`
deacetylation of O-acetylserine and sulfhydrylation using CysK1 `Reactome:R-MTU-936642`	produces	acetic acid `CHEBI:15366`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction4 places physical entity SmallMolecule14 on its right side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction4/bp:right/#SmallMolecule14; #BiochemicalReaction4/bp:conversionDirection`
deacetylation of O-acetylserine and sulfhydrylation using CysK1 `Reactome:R-MTU-936642`	produces	L-cysteine zwitterion `CHEBI:35235`	Reactome:R-MTU-936721 Source assertion: BioPAX BiochemicalReaction4 places physical entity SmallMolecule15 on its right side; conversion direction is LEFT-TO-RIGHT; displayed orientation is LEFT-TO-RIGHT. Source location `#BiochemicalReaction4/bp:right/#SmallMolecule15; #BiochemicalReaction4/bp:conversionDirection`
deacetylation of O-acetylserine and sulfhydrylation using CysK1 `Reactome:R-MTU-936642`	occurs_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: All physical entities on both sides of BioPAX BiochemicalReaction4 have the same cellular location. Source location `#BiochemicalReaction4/bp:left\|bp:right; physicalEntity/bp:cellularLocation/#CellularLocationVocabulary1`
CysH holoenzyme `Reactome:R-MTU-936704`	catalyzes	sulfite results from reduction of APS `Reactome:R-MTU-936655`	Reactome:R-MTU-936721 Source assertion: BioPAX Catalysis1 names Complex1 as its catalytic controller. Source location `#Catalysis1/bp:controller/#Complex1; bp:controlled/#BiochemicalReaction1`
Sir holoenzyme `Reactome:R-MTU-936607`	catalyzes Reactome assigns this Sir holoenzyme to sulfite reduction. PMID17644602 assayed purified M. tuberculosis SirA with methyl viologen; its deletion physiology was in M. smegmatis, not direct validation of this particular ferredoxin pair.	sulfite is reduced to sulfide `Reactome:R-MTU-936703`	Reactome:R-MTU-936721 Source assertion: BioPAX Catalysis2 names Complex4 as its catalytic controller. Source location `#Catalysis2/bp:controller/#Complex4; bp:controlled/#BiochemicalReaction2`
CysE `Reactome:R-MTU-936604`	catalyzes Direct recombinant H37Rv CysE characterization supersedes the source comment that direct biochemical evidence was unavailable.	acetylation of serine `Reactome:R-MTU-936615`	Reactome:R-MTU-936721 Source assertion: BioPAX Catalysis3 names Protein6 as its catalytic controller. Source location `#Catalysis3/bp:controller/#Protein6; bp:controlled/#BiochemicalReaction3` PMID:23483228 The serine acetyltransferase activity of M. tuberculosis CysE protein was detected.
CysK1 dimer `Reactome:R-MTU-936755`	catalyzes	deacetylation of O-acetylserine and sulfhydrylation using CysK1 `Reactome:R-MTU-936642`	Reactome:R-MTU-936721 Source assertion: BioPAX Catalysis4 names Complex5 as its catalytic controller. Source location `#Catalysis4/bp:controller/#Complex5; bp:controlled/#BiochemicalReaction4`
sulfide(2-) `CHEBI:15138`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule7 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule7/bp:cellularLocation/#CellularLocationVocabulary1`
water `CHEBI:15377`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule6 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule6/bp:cellularLocation/#CellularLocationVocabulary1`
adenosine 5'-monophosphate(2-) `CHEBI:456215`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule4 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule4/bp:cellularLocation/#CellularLocationVocabulary1`
sulfurous acid `CHEBI:48854`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule3 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule3/bp:cellularLocation/#CellularLocationVocabulary1`
hydron `CHEBI:15378`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule2 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule2/bp:cellularLocation/#CellularLocationVocabulary1`
L-cysteine zwitterion `CHEBI:35235`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule15 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule15/bp:cellularLocation/#CellularLocationVocabulary1`
acetic acid `CHEBI:15366`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule14 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule14/bp:cellularLocation/#CellularLocationVocabulary1`
coenzyme A(4-) `CHEBI:57287`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule13 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule13/bp:cellularLocation/#CellularLocationVocabulary1`
O-acetyl-L-serine `CHEBI:17981`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule12 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule12/bp:cellularLocation/#CellularLocationVocabulary1`
L-serine zwitterion `CHEBI:33384`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule11 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule11/bp:cellularLocation/#CellularLocationVocabulary1`
acetyl-CoA(4-) `CHEBI:57288`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule10 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule10/bp:cellularLocation/#CellularLocationVocabulary1`
5'-adenylyl sulfate(2-) `CHEBI:58243`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule1 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule1/bp:cellularLocation/#CellularLocationVocabulary1`
CysE `Reactome:R-MTU-936604`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity Protein6 is assigned to cellular location CellularLocationVocabulary1. Source location `#Protein6/bp:cellularLocation/#CellularLocationVocabulary1`
TrxA(ox.) `Reactome:R-MTU-1222293`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity Protein2 is assigned to cellular location CellularLocationVocabulary1. Source location `#Protein2/bp:cellularLocation/#CellularLocationVocabulary1`
Trx(red.) `Reactome:R-MTU-936674`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity Protein1 is assigned to cellular location CellularLocationVocabulary1. Source location `#Protein1/bp:cellularLocation/#CellularLocationVocabulary1`
CysK1 dimer `Reactome:R-MTU-936755`	has_part	PXLP-K44-CysK1 `Reactome:R-MTU-936587`	Reactome:R-MTU-936721 Source assertion: BioPAX complex Complex5 explicitly includes physical entity Protein7. Source location `#Complex5/bp:component/#Protein7`
CysK1 dimer `Reactome:R-MTU-936755`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity Complex5 is assigned to cellular location CellularLocationVocabulary1. Source location `#Complex5/bp:cellularLocation/#CellularLocationVocabulary1`
PXLP-K44-CysK1 `Reactome:R-MTU-936587`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity Protein7 is assigned to cellular location CellularLocationVocabulary1. Source location `#Protein7/bp:cellularLocation/#CellularLocationVocabulary1`
Sir holoenzyme `Reactome:R-MTU-936607`	has_part	siroheme `CHEBI:28599`	Reactome:R-MTU-936721 Source assertion: BioPAX complex Complex4 explicitly includes physical entity SmallMolecule9. Source location `#Complex4/bp:component/#SmallMolecule9`
Sir holoenzyme `Reactome:R-MTU-936607`	has_part	Iron Sulfur Cluster `Reactome:R-ALL-70986`	Reactome:R-MTU-936721 Source assertion: BioPAX complex Complex4 explicitly includes physical entity PhysicalEntity1. Source location `#Complex4/bp:component/#PhysicalEntity1`
Sir holoenzyme `Reactome:R-MTU-936607`	has_part	Sir `Reactome:R-MTU-936705`	Reactome:R-MTU-936721 Source assertion: BioPAX complex Complex4 explicitly includes physical entity Protein5. Source location `#Complex4/bp:component/#Protein5`
Sir holoenzyme `Reactome:R-MTU-936607`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity Complex4 is assigned to cellular location CellularLocationVocabulary1. Source location `#Complex4/bp:cellularLocation/#CellularLocationVocabulary1`
Sir `Reactome:R-MTU-936705`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity Protein5 is assigned to cellular location CellularLocationVocabulary1. Source location `#Protein5/bp:cellularLocation/#CellularLocationVocabulary1`
Iron Sulfur Cluster `Reactome:R-ALL-70986`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity PhysicalEntity1 is assigned to cellular location CellularLocationVocabulary1. Source location `#PhysicalEntity1/bp:cellularLocation/#CellularLocationVocabulary1`
siroheme `CHEBI:28599`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule9 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule9/bp:cellularLocation/#CellularLocationVocabulary1`
Fdx(ox.) `Reactome:R-MTU-937267`	has_part	Fdx `Reactome:R-MTU-937262`	Reactome:R-MTU-936721 Source assertion: BioPAX complex Complex3 explicitly includes physical entity Protein4. Source location `#Complex3/bp:component/#Protein4`
Fdx(ox.) `Reactome:R-MTU-937267`	has_part Retained as partial source composition, without the source cluster stoichiometry. UniProt P9WNE7 annotates one [4Fe-4S] and one [3Fe-4S] cluster by similarity; this edge does not assert complete composition.	tetra-mu3-sulfido-tetrairon(2+) `CHEBI:33722`	Reactome:R-MTU-936721 Source assertion: BioPAX complex Complex3 explicitly includes physical entity SmallMolecule8. Source location `#Complex3/bp:component/#SmallMolecule8` UniProtKB:P9WNE7 Source assertion: The COFACTOR annotations list one [4Fe-4S] and one [3Fe-4S] cluster, each with ECO:0000250 similarity evidence. They do not establish the charge of each cluster in this native source state. Source location `$.results[12].comments[1:3]`
Fdx(ox.) `Reactome:R-MTU-937267`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity Complex3 is assigned to cellular location CellularLocationVocabulary1. Source location `#Complex3/bp:cellularLocation/#CellularLocationVocabulary1`
tetra-mu3-sulfido-tetrairon(1+) `CHEBI:33723`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule5 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule5/bp:cellularLocation/#CellularLocationVocabulary1`
tetra-mu3-sulfido-tetrairon(2+) `CHEBI:33722`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity SmallMolecule8 is assigned to cellular location CellularLocationVocabulary1. Source location `#SmallMolecule8/bp:cellularLocation/#CellularLocationVocabulary1`
Fdx `Reactome:R-MTU-937262`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity Protein4 is assigned to cellular location CellularLocationVocabulary1. Source location `#Protein4/bp:cellularLocation/#CellularLocationVocabulary1`
Fdx(red.) `Reactome:R-MTU-937263`	has_part	Fdx `Reactome:R-MTU-937262`	Reactome:R-MTU-936721 Source assertion: BioPAX complex Complex2 explicitly includes physical entity Protein4. Source location `#Complex2/bp:component/#Protein4`
Fdx(red.) `Reactome:R-MTU-937263`	has_part Retained as partial source composition, without the source cluster stoichiometry. UniProt P9WNE7 annotates one [4Fe-4S] and one [3Fe-4S] cluster by similarity; this edge does not assert complete composition.	tetra-mu3-sulfido-tetrairon(1+) `CHEBI:33723`	Reactome:R-MTU-936721 Source assertion: BioPAX complex Complex2 explicitly includes physical entity SmallMolecule5. Source location `#Complex2/bp:component/#SmallMolecule5` UniProtKB:P9WNE7 Source assertion: The COFACTOR annotations list one [4Fe-4S] and one [3Fe-4S] cluster, each with ECO:0000250 similarity evidence. They do not establish the charge of each cluster in this native source state. Source location `$.results[12].comments[1:3]`
Fdx(red.) `Reactome:R-MTU-937263`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity Complex2 is assigned to cellular location CellularLocationVocabulary1. Source location `#Complex2/bp:cellularLocation/#CellularLocationVocabulary1`
CysH holoenzyme `Reactome:R-MTU-936704`	has_part	Iron Sulfur Cluster `Reactome:R-ALL-70986`	Reactome:R-MTU-936721 Source assertion: BioPAX complex Complex1 explicitly includes physical entity PhysicalEntity1. Source location `#Complex1/bp:component/#PhysicalEntity1`
CysH holoenzyme `Reactome:R-MTU-936704`	has_part	CysH `Reactome:R-MTU-936694`	Reactome:R-MTU-936721 Source assertion: BioPAX complex Complex1 explicitly includes physical entity Protein3. Source location `#Complex1/bp:component/#Protein3`
CysH holoenzyme `Reactome:R-MTU-936704`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity Complex1 is assigned to cellular location CellularLocationVocabulary1. Source location `#Complex1/bp:cellularLocation/#CellularLocationVocabulary1`
CysH `Reactome:R-MTU-936694`	located_in	cytosol `GO:0005829`	Reactome:R-MTU-936721 Source assertion: BioPAX physical entity Protein3 is assigned to cellular location CellularLocationVocabulary1. Source location `#Protein3/bp:cellularLocation/#CellularLocationVocabulary1`
sulfite results from reduction of APS `Reactome:R-MTU-936655`	provides_input_for Source-ordered material transfer through CHEBI:48854; no regulatory sign or stoichiometric coefficient is asserted.	sulfite is reduced to sulfide `Reactome:R-MTU-936703`	Reactome:R-MTU-936721 Source assertion: BioPAX PathwayStep1 explicitly lists PathwayStep2 as nextStep; the linked reactions produce and consume the same source physical entity. Source location `#PathwayStep1/bp:nextStep/#PathwayStep2; #BiochemicalReaction1/bp:right/#SmallMolecule3; #BiochemicalReaction1/bp:conversionDirection; #BiochemicalReaction2/bp:left/#SmallMolecule3; #BiochemicalReaction2/bp:conversionDirection`
sulfite is reduced to sulfide `Reactome:R-MTU-936703`	provides_input_for Source-ordered material transfer through CHEBI:15138; no regulatory sign or stoichiometric coefficient is asserted.	deacetylation of O-acetylserine and sulfhydrylation using CysK1 `Reactome:R-MTU-936642`	Reactome:R-MTU-936721 Source assertion: BioPAX PathwayStep2 explicitly lists PathwayStep4 as nextStep; the linked reactions produce and consume the same source physical entity. Source location `#PathwayStep2/bp:nextStep/#PathwayStep4; #BiochemicalReaction2/bp:right/#SmallMolecule7; #BiochemicalReaction2/bp:conversionDirection; #BiochemicalReaction4/bp:left/#SmallMolecule7; #BiochemicalReaction4/bp:conversionDirection`
acetylation of serine `Reactome:R-MTU-936615`	provides_input_for Source-ordered material transfer through CHEBI:17981; no regulatory sign or stoichiometric coefficient is asserted.	deacetylation of O-acetylserine and sulfhydrylation using CysK1 `Reactome:R-MTU-936642`	Reactome:R-MTU-936721 Source assertion: BioPAX PathwayStep3 explicitly lists PathwayStep4 as nextStep; the linked reactions produce and consume the same source physical entity. Source location `#PathwayStep3/bp:nextStep/#PathwayStep4; #BiochemicalReaction3/bp:right/#SmallMolecule12; #BiochemicalReaction3/bp:conversionDirection; #BiochemicalReaction4/bp:left/#SmallMolecule12; #BiochemicalReaction4/bp:conversionDirection`

References

PMID:12072441 5'-adenosinephosphosulfate lies at a metabolic branch point in mycobacteria
PMID:16008502 A conserved mechanism for sulfonucleotide reduction
PMID:17644602 Sulfite reduction in mycobacteria
PMID:15917234 Siroheme- and [Fe4-S4]-dependent NirA from Mycobacterium tuberculosis is a sulfite reductase with a covalent Cys-Tyr bond in the active site
PMID:17567578 Structural insights into catalysis and inhibition of O-acetylserine sulfhydrylase from Mycobacterium tuberculosis. Crystal structures of the enzyme alpha-aminoacrylate intermediate and an enzyme-inhibitor complex
PMID:16436075 Functional analysis of L-serine O-acetyltransferase from Corynebacterium glutamicum
PMID:19376862 Functional genomics reveals extended roles of the Mycobacterium tuberculosis stress response factor sigmaH
PMID:17970225 Drug targets in mycobacterial sulfur metabolism
Reactome:R-MTU-936721 BioPAX source pathway Reactome:R-MTU-936721 (source version: Reactome release 97)
PMID:25022854 CysK2 from Mycobacterium tuberculosis Is an O-Phospho-L-Serine-Dependent S-Sulfocysteine Synthase
PMID:23483228 Identification and characterization of serine acetyltransferase encoded by the Mycobacterium tuberculosis Rv2335 gene
UniProtKB:P9WNE7 UniProtKB P9WNE7 ferredoxin cofactor annotations (source version: retrieved 2026-10-07; release not exposed)

Curation history

2026-10-07T07:37:15Z Codex
- CREATE — Curate Reactome:R-MTU-936721 with native physical states and reviewed chemistry
  Added 4 reactions and 69 edges from hash-pinned Reactome release 97. Complete source projection and edge-disposition ledger are in research/source_discovery/2026-10-07-reactome. Preserve modified, redox and cleaved protein states; exclude unsupported sulfur charging and CysK2/OAS chemistry where relevant; correct GTP coupling in sulfate activation. Exact source and primary-evidence limitations are explicit. Native and closed-schema validation passed before writing. Hidden/ignored-file deduplication included.
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