TmaR condensate

cellstructuremech:tmar_condensate · Ribonucleoprotein · Other · Proposed

A polar, membraneless ribonucleoprotein condensate organized by TmaR in Escherichia coli that recruits phosphotransferase-system enzyme I and participates in spatial regulation of sugar utilization. [DOI:10.1016/j.celrep.2025.115436]

Synonyms: TmaR-EI polar condensate

Part of: GO:0005737 — cytoplasm (no local record)

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Genes	Essential	Role
PTS system regulator TmaR	Protein	part of	`NCBIfam:NF040881`	tmaR	ESSENTIAL	Defining scaffold of the polar condensate and recruiter of enzyme I. `DOI:10.1016/j.celrep.2025.115436` Native-locus imaging and recruitment mutants separate TmaR clustering from EI recruitment (Figures 1F-G and 2D). `https://www.ncbi.nlm.nih.gov/genome/annotation_prok/evidence/NF040881/` Live authority model: NF040881.1, source NCBIFAM, family_type equivalog, product_name PTS system regulator TmaR; checked 2026-10-03.
Phosphotransferase system, enzyme I	Protein	part of	`InterPro:IPR024692`	ptsI	DISPENSABLE	Recruited enzyme client. Native bacterial TmaR condensates can form without EI; recruitment regulates sugar utilization. `DOI:10.1016/j.celrep.2025.115436` Results explicitly distinguish EI-independent bacterial TmaR condensation from two-protein reconstitution in yeast. Figures 1-3 test client recruitment and interaction.
RNA	Rna	part of	`SO:0000356`		UNKNOWN	Heterotypic condensation partner and transcript cargo; no universal RNA-species requirement or exhaustive cargo inventory is asserted. `DOI:10.1016/j.celrep.2023.113393` Readable final-paper abstract reports RNA-dependent heterotypic phase separation in vivo and in vitro and protection of flagellar transcripts. Full Results were not accessible through the attempted publisher routes; specific RNA identities and quantitative requirements are not imported.

Canonical examples

NCBITaxon:511145 Escherichia coli str. K-12 substr. MG1655 — Key resources and strain-construction Methods identify MG1655 derivatives for native-locus TmaR-YFP/EI-mCherry imaging. Standard growth uses supplemented M9-glucose at 30 C; individual biochemical and sugar-consumption assays also use specified plasmids. This example is not a species-wide prevalence claim. [DOI:10.1016/j.celrep.2025.115436]

Functions

Spatial regulation of sugar utilization — Polar retention of EI by TmaR limits EI-dependent sugar consumption in the tested E. coli backgrounds.
- DOI:10.1016/j.celrep.2025.115436 Figures 1-3 combine localization and interaction perturbations with consumption assays. F8L and V11I recruitment-defective TmaR variants show elevated glucose consumption. This is not a direct measurement of transport flux or the catalytic state of each condensed EI molecule.
Flagellar transcript protection — The primary report associates protection of flagella-related transcripts in TmaR condensates with control of flagella production and motility.
- DOI:10.1016/j.celrep.2023.113393 Supported at the level of the readable final-paper abstract. Transcript-specific half-lives, exact cargo membership and downstream causal edges await full-text assessment.

Mechanism graphs

TmaR condensation couples EI retention to sugar-use control (FUNCTION)

RNA-associated TmaR condensation supports polar EI retention and regulation of sugar consumption.

Subject	Predicate	Object	Evidence
PTS system regulator TmaR	undergoes	TmaR condensation	`DOI:10.1016/j.celrep.2023.113393` Final-paper abstract reports cellular and reconstituted phase separation; no material-property numbers are imported.
RNA	promotes	TmaR condensation	`DOI:10.1016/j.celrep.2023.113393` The abstract identifies RNA as an in vivo and in vitro condensation partner, without establishing every RNA species as necessary.
TmaR condensation	forms	TmaR condensate	`DOI:10.1016/j.celrep.2023.113393` The final abstract connects TmaR condensation with its polar organization and transcript-related function.
PTS system regulator TmaR	interacts with	Phosphotransferase system, enzyme I	`DOI:10.1016/j.celrep.2025.115436` Figures 1I and 3A-B, far-western controls and bacterial two-hybrid assays support interaction. G266 effects differ between assays; overexpression can compensate reduced interaction.
TmaR condensate	supports	Polar EI retention	`DOI:10.1016/j.celrep.2025.115436` Native chromosomal reporters colocalize; TmaR recruitment mutants retain foci while EI becomes diffuse (Figures 1F-G and 2D). Some variants also alter scaffold abundance.
Phosphotransferase system, enzyme I	undergoes	Polar EI retention	`DOI:10.1016/j.celrep.2025.115436` EI localization shifts with TmaR abundance and EI/TmaR interaction mutations; no fixed occupancy or stoichiometry is inferred.
Polar EI retention	restrains	EI-dependent sugar consumption	`DOI:10.1016/j.celrep.2025.115436` Figure 3D-E links recruitment-defective variants to altered sugar consumption. The interpretation combines localization and functional perturbations; it is not a purified condensate-specific enzyme assay.

Discussions

CURATION_TODO (RESOLVED): Distinguish the TmaR scaffolded condensate from a protein, one EI-TmaR complex and the H-body. Shared polar location and stress-induced co-condensation do not imply identical structure identity or permanent parthood.
CURATION_TODO (RESOLVED): Resolve TmaR at its issuing family authority rather than substituting a generic sequence family. InterPro's DUF496 and unreviewed UPF0265 descriptions alone do not establish the intended functional class.
CURATION_TODO (RESOLVED): Keep scaffold/client essentiality and native organism scope separate from heterologous reconstitution. EI and TmaR require co-expression for the tested yeast condensates, unlike native bacterial TmaR foci. Plasmid cross-species complementation is not endogenous taxonomic prevalence. Post-PR review found that calling HPr merely a modeled EI partner conflated established EI-HPr interaction with the proposed TmaR-dependent exclusion mechanism.
CURATION_TODO (RESOLVED): Do not promote docking, consumption measurements or discordant significance descriptions into stronger claims. The 2025 interface is a model with mutational support, not an experimentally solved EI-TmaR complex. Figure 3E marks K95E, whereas the Results text singles out A84G among patch-II variants.
CURATION_TODO (OPEN): Assess the full 2023 primary experiments before adding specific RNA cargo or transcript-stability mechanisms. The verified abstract supports RNA-assisted assembly and flagellar transcript protection but not an exhaustive cargo list, quantitative half-lives or universal necessity.

Evidence

DOI:10.1016/j.celrep.2025.115436 Albocher-Kedem et al. 2025; PMC11937232. Full Results, relevant Methods, limitations and MG1655 resource table read through PMC BioC and Europe PMC JATS. Figures 1 and 3 visually inspected; downloaded bytes match PMC metadata MD5. CC BY-NC-ND figures are not hosted.
DOI:10.1016/j.celrep.2023.113393 Szoke et al. 2023; PMID 37934665. Final-paper abstract verified at Europe PMC and the publisher. Publisher full-text routes returned access errors; no full Results reading or preprint substitution is claimed.
DOI:10.1371/journal.pbio.3003775 Guan et al. 2026; Figure 1L and corresponding Results independently show TmaR foci without Hfq or polyP, supporting a boundary from the Hfq-organized H-body.

Curation history

2026-10-03T13:51:01Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-03T13:52:49Z codex · EXPANDED_RECORD — Added three grounded component classes, MG1655 example, two source-bounded functions, seven-edge mechanism graph, native/H-body boundaries and an explicit RNA-evidence follow-up; verified exact NCBIfam TmaR equivalog.
2026-10-03T14:08:25Z codex · CORRECTED_EVIDENCE_SCOPE — Addressed review issue #1987 by separating established EI-HPr partnership from modeled HPr exclusion by TmaR-bound EI; no component or mechanism expansion.

Source: data/structures/ribonucleoprotein/tmar_condensate.yaml