L-rhamnose degradation I

MetaCyc:RHAMCAT-PWY

L-rhamnose degradation I converts alpha-L-rhamnose to beta-L-rhamnose, isomerizes L-rhamnopyranose to L-rhamnulose, cyclizes keto-L-rhamnulose to L-rhamnulofuranose, phosphorylates L-rhamnulose with ATP, and cleaves L-rhamnulose 1-phosphate to (S)-lactaldehyde and dihydroxyacetone phosphate.

Pathway type

carbohydrate degradation

Organism scope

Bacteria NCBITaxon:2

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Pathway network

20 nodes · 22 asserted directed edges

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Reaction / activity
Chemical / cofactor
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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
Bacteria `NCBITaxon:2`	taxon
L-rhamnose mutarotase `EC:5.1.3.32`	molecular activity
L-rhamnose isomerase `EC:5.3.1.14`	molecular activity
rhamnulokinase `EC:2.7.1.5`	molecular activity
rhamnulose-1-phosphate aldolase `EC:4.1.2.19`	molecular activity
alpha-L-rhamnose `CHEBI:27907`	small molecule
beta-L-rhamnose `CHEBI:27586`	small molecule
L-rhamnopyranose `CHEBI:62346`	small molecule
L-rhamnulose `CHEBI:17897`	small molecule
L-rhamnulofuranose `MetaCyc:CPD-16567`	small molecule
ATP `CHEBI:30616`	small molecule
L-rhamnulose 1-phosphate `CHEBI:58313`	small molecule
ADP `CHEBI:456216`	small molecule
H(+) `CHEBI:15378`	small molecule
(S)-lactaldehyde `CHEBI:18041`	small molecule
dihydroxyacetone phosphate `CHEBI:57642`	small molecule
keto-L-rhamnulose cyclization reaction `MetaCyc:RXN-15356`	reaction	left to right
rhamnulokinase reaction `RHEA:20118`	reaction	left to right
L-rhamnose mutarotase reaction `RHEA:25585`	reaction	left to right
L-rhamnose isomerase reaction `RHEA:23161`	reaction	left to right
rhamnulose-1-phosphate aldolase reaction `RHEA:19690`	reaction	left to right

Mechanistic edges

Mechanistic edges and their cited evidence
Subject	Predicate and description	Object	Evidence
L-rhamnulose `CHEBI:17897`	consumes	keto-L-rhamnulose cyclization reaction `MetaCyc:RXN-15356`	MetaCyc:RXN-15356 Source assertion: MetaCyc assigns CHEBI:17897 consumes MetaCyc:RXN-15356 in the spontaneous rhamnulose cyclization. Source location `Reaction[@frameid='RXN-15356']/left\|right; native compound cross-references`
keto-L-rhamnulose cyclization reaction `MetaCyc:RXN-15356`	produces	L-rhamnulofuranose `MetaCyc:CPD-16567`	MetaCyc:RXN-15356 Source assertion: MetaCyc assigns MetaCyc:RXN-15356 produces MetaCyc:CPD-16567 in the spontaneous rhamnulose cyclization. Source location `Reaction[@frameid='RXN-15356']/left\|right; native compound cross-references`
L-rhamnulose `CHEBI:17897`	consumes	rhamnulokinase reaction `RHEA:20118`	RHEA:20118 Source assertion: Rhea lists CHEBI:17897 on the substrates side of RHEA:20118 in this directed reaction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/20118']/rh:substrates; rh:contains/rh:compound/rh:accession`
ATP `CHEBI:30616`	consumes	rhamnulokinase reaction `RHEA:20118`	RHEA:20118 Source assertion: Rhea lists CHEBI:30616 on the substrates side of RHEA:20118 in this directed reaction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/20118']/rh:substrates; rh:contains/rh:compound/rh:accession`
rhamnulokinase reaction `RHEA:20118`	produces	H(+) `CHEBI:15378`	RHEA:20118 Source assertion: Rhea lists CHEBI:15378 on the products side of RHEA:20118 in this directed reaction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/20118']/rh:products; rh:contains/rh:compound/rh:accession`
rhamnulokinase reaction `RHEA:20118`	produces	ADP `CHEBI:456216`	RHEA:20118 Source assertion: Rhea lists CHEBI:456216 on the products side of RHEA:20118 in this directed reaction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/20118']/rh:products; rh:contains/rh:compound/rh:accession`
rhamnulokinase reaction `RHEA:20118`	produces	L-rhamnulose 1-phosphate `CHEBI:58313`	RHEA:20118 Source assertion: Rhea lists CHEBI:58313 on the products side of RHEA:20118 in this directed reaction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/20118']/rh:products; rh:contains/rh:compound/rh:accession`
alpha-L-rhamnose `CHEBI:27907`	consumes	L-rhamnose mutarotase reaction `RHEA:25585`	RHEA:25585 Source assertion: Rhea lists CHEBI:27907 on the substrates side of RHEA:25585 in this directed reaction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/25585']/rh:substrates; rh:contains/rh:compound/rh:accession`
L-rhamnose mutarotase reaction `RHEA:25585`	produces	beta-L-rhamnose `CHEBI:27586`	RHEA:25585 Source assertion: Rhea lists CHEBI:27586 on the products side of RHEA:25585 in this directed reaction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/25585']/rh:products; rh:contains/rh:compound/rh:accession`
L-rhamnopyranose `CHEBI:62346`	consumes	L-rhamnose isomerase reaction `RHEA:23161`	RHEA:23161 Source assertion: Rhea lists CHEBI:62346 on the substrates side of RHEA:23161 in this directed reaction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/23161']/rh:substrates; rh:contains/rh:compound/rh:accession`
L-rhamnose isomerase reaction `RHEA:23161`	produces	L-rhamnulose `CHEBI:17897`	RHEA:23161 Source assertion: Rhea lists CHEBI:17897 on the products side of RHEA:23161 in this directed reaction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/23161']/rh:products; rh:contains/rh:compound/rh:accession`
L-rhamnulose 1-phosphate `CHEBI:58313`	consumes	rhamnulose-1-phosphate aldolase reaction `RHEA:19690`	RHEA:19690 Source assertion: Rhea lists CHEBI:58313 on the substrates side of RHEA:19690 in this directed reaction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/19690']/rh:substrates; rh:contains/rh:compound/rh:accession`
rhamnulose-1-phosphate aldolase reaction `RHEA:19690`	produces	(S)-lactaldehyde `CHEBI:18041`	RHEA:19690 Source assertion: Rhea lists CHEBI:18041 on the products side of RHEA:19690 in this directed reaction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/19690']/rh:products; rh:contains/rh:compound/rh:accession`
rhamnulose-1-phosphate aldolase reaction `RHEA:19690`	produces	dihydroxyacetone phosphate `CHEBI:57642`	RHEA:19690 Source assertion: Rhea lists CHEBI:57642 on the products side of RHEA:19690 in this directed reaction. Source location `rdf:Description[@rdf:about='http://rdf.rhea-db.org/19690']/rh:products; rh:contains/rh:compound/rh:accession`
L-rhamnose mutarotase `EC:5.1.3.32`	catalyzes	L-rhamnose mutarotase reaction `RHEA:25585`	RHEA:25584 Source assertion: Rhea associates EC:5.1.3.32 with the reaction family containing RHEA:25585. Source location `rh:ec`
L-rhamnose isomerase `EC:5.3.1.14`	catalyzes	L-rhamnose isomerase reaction `RHEA:23161`	RHEA:23160 Source assertion: Rhea associates EC:5.3.1.14 with the reaction family containing RHEA:23161. Source location `rh:ec`
rhamnulokinase `EC:2.7.1.5`	catalyzes	rhamnulokinase reaction `RHEA:20118`	RHEA:20117 Source assertion: Rhea associates EC:2.7.1.5 with the reaction family containing RHEA:20118. Source location `rh:ec`
rhamnulose-1-phosphate aldolase `EC:4.1.2.19`	catalyzes	rhamnulose-1-phosphate aldolase reaction `RHEA:19690`	RHEA:19689 Source assertion: Rhea associates EC:4.1.2.19 with the reaction family containing RHEA:19690. Source location `rh:ec`
keto-L-rhamnulose cyclization reaction `MetaCyc:RXN-15356`	precedes	rhamnulokinase reaction `RHEA:20118`	MetaCyc:RHAMCAT-PWY Source assertion: MetaCyc pathway ordering places MetaCyc:RXN-15356 before RHEA:20118 in this pathway. The source ordering may bridge anomer-specific and broader substrate classes. Source location `Pathway/reaction-ordering and reaction-layout; Rhea-to-MetaCyc cross-references`
rhamnulokinase reaction `RHEA:20118`	precedes	rhamnulose-1-phosphate aldolase reaction `RHEA:19690`	MetaCyc:RHAMCAT-PWY Source assertion: MetaCyc pathway ordering places RHEA:20118 before RHEA:19690 in this pathway. Shared intermediate: CHEBI:58313. Source location `Pathway/reaction-ordering and reaction-layout; Rhea-to-MetaCyc cross-references`
L-rhamnose isomerase reaction `RHEA:23161`	precedes	keto-L-rhamnulose cyclization reaction `MetaCyc:RXN-15356`	MetaCyc:RHAMCAT-PWY Source assertion: MetaCyc pathway ordering places RHEA:23161 before MetaCyc:RXN-15356 in this pathway. The source ordering may bridge anomer-specific and broader substrate classes. Source location `Pathway/reaction-ordering and reaction-layout; Rhea-to-MetaCyc cross-references`
L-rhamnose mutarotase reaction `RHEA:25585`	precedes	L-rhamnose isomerase reaction `RHEA:23161`	MetaCyc:RHAMCAT-PWY Source assertion: MetaCyc pathway ordering places RHEA:25585 before RHEA:23161 in this pathway. The source ordering may bridge anomer-specific and broader substrate classes. Source location `Pathway/reaction-ordering and reaction-layout; Rhea-to-MetaCyc cross-references`

References

MetaCyc:RHAMCAT-PWY MetaCyc L-rhamnose degradation I (source version: 22.5)
RHEA:25584 Rhea L-rhamnose mutarotase reaction (source version: 139)
RHEA:25587 Rhea bidirectional L-rhamnose mutarotase reaction (source version: 139)
RHEA:23160 Rhea L-rhamnose isomerase reaction (source version: 139)
RHEA:23163 Rhea bidirectional L-rhamnose isomerase reaction (source version: 139)
RHEA:20117 Rhea generic rhamnulokinase reaction (source version: 139)
RHEA:20118 Rhea L-rhamnulose-1-phosphate-forming direction (source version: 139)
RHEA:19689 Rhea generic rhamnulose-1-phosphate aldolase reaction (source version: 139)
RHEA:19692 Rhea bidirectional rhamnulose-1-phosphate aldolase reaction (source version: 139)
MetaCyc:RXN-15356 MetaCyc:RXN-15356 authority record (source version: 22.5)
RHEA:25585 RHEA:25585 authority record (source version: 139)
RHEA:23161 RHEA:23161 authority record (source version: 139)
RHEA:19690 RHEA:19690 authority record (source version: 139)

Curation history

2026-10-05T06:25:52Z codex
- EDIT — Review causal chemistry and add sourced molecular context
  Reviewed the entire record against MetaCyc 22.5 native pathway XML (including nested pathways), Rhea 139 explicit sides and directions, ENZYME 02-Sep-2026, PubMed records, and reviewed UniProt 2026_03 annotations within the record's taxon scope. Replaced generated structured-source quotations with source_assertion and source_locator. Typed molecular activities and participants. Reaction count 5 to 5; 3 directed-ID corrections; 0 protein annotations, 0 cofactor annotations and 0 sourced locations. All Rhea reaction substrate/product sets checked against independent Rhea authority; native pathway leaf coverage and source exceptions recorded in reports/causal_graph_review/metacyc-review.json. Full source URLs, versions and byte hashes are in metacyc-sources.json. All 50 MetaCyc records passed native schema validation; six targeted chemistry/evidence regression tests passed. Missing protein or cofactor annotations are not treated as biological absence; qualifications and exclusions are preserved in the ledger.
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