Finding step cstA for pyruvate catabolism in Rubrivirga marina SAORIC-28
No candidates for cstA: large subunit of pyruvate transporter (CstA)
GapMind classifies a step as low confidence even if it does not find any candidates. You can still try to find candidates by using Curated BLAST (which searches the 6-frame translation) or by text search of the annotations (which may indicate weak homology, under 30% identity or 50% coverage, that GapMind does not consider). See the links below.
Definition of step cstA
- UniProt sequence A0A0C4Y7X7: SubName: Full=Carbon starvation protein A {ECO:0000313|EMBL:AJG21527.1};
- Curated sequence P15078: Peptide transporter CstA; Carbon starvation protein A. carbon starvation protein A
- Curated sequence P39396: Pyruvate/proton symporter BtsT; Brenztraubensaure transporter; Pyruvate/H(+) symporter. pyruvate:H+ symporter. pyruvate:H+ symporter
- UniProt sequence A0A0N9VZ52: SubName: Full=Carbon starvation protein A {ECO:0000313|EMBL:ALI04206.1};
- Ignore hits to Q0P9Y2 when looking for 'other' hits (Peptide transporter CstA; Carbon starvation protein A. CstA of 703 aas and 18 putative TMSs. In C. jejuni, this protein plays a role in starvation responses and peptide uptake. A ΔcstA mutant has reduced use of di- and tri-peptides when used as nitrogen sources. The mutant also has reduced motility and agglutination and shows decreased host-pathogen relationships)
- Comment: E. coli cstA (P15078) was originally thought to be a peptide transporter, but is involved in pyruvate transport along with ybdD (PMID:29358499). The related protein btsT (P39396, formerly yjiY) is also a pyruvate transporter. And a similar protein from Cupriavidus basilensis, RR42_RS20515 = A0A0C4Y7X7, is important for pyruvate utilization. As is AO353_25255 (A0A0N9VZ52) from Pseudomonas fluorescens FW300-N2E3. CstA and RR42_RS20515 seem to operate together with ybdD or similar proteins, but purified BtsT is reported to transport pyruvate (PMID:29061664), so it may not require a ybdD-like component. It is not clear if AO353_25255 functions with a ybdD-like component: the downstream gene, AO353_25260, is ybdD-like and has subtle defects during growth on pyruvate. Q0P9Y2 (CSTA_CAMJE) was proposed to be a peptide transporter in Campylobacter jejuni, but is suspiciously similar to pyruvate transporters, so is ignored.
Or cluster all characterized cstA proteins
This GapMind analysis is from Sep 24 2021. The underlying query database was built on Sep 17 2021.
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About GapMind
Each pathway is defined by a set of rules based on individual steps or genes. Candidates for each step are identified by using
ublast (a fast alternative to protein BLAST)
against a database of manually-curated proteins (most of which are experimentally characterized) or by using
HMMer with enzyme models (usually from
TIGRFam). Ublast hits may be split across two different proteins.
A candidate for a step is "high confidence" if either:
- ublast finds a hit to a characterized protein at above 40% identity and 80% coverage, and bits >= other bits+10.
- (Hits to curated proteins without experimental data as to their function are never considered high confidence.)
- HMMer finds a hit with 80% coverage of the model, and either other identity < 40 or other coverage < 0.75.
where "other" refers to the best ublast hit to a sequence that is not annotated as performing this step (and is not "ignored").
Otherwise, a candidate is "medium confidence" if either:
- ublast finds a hit at above 40% identity and 70% coverage (ignoring otherBits).
- ublast finds a hit at above 30% identity and 80% coverage, and bits >= other bits.
- HMMer finds a hit (regardless of coverage or other bits).
Other blast hits with at least 50% coverage are "low confidence."
Steps with no high- or medium-confidence candidates may be considered "gaps."
For the typical bacterium that can make all 20 amino acids, there are 1-2 gaps in amino acid biosynthesis pathways.
For diverse bacteria and archaea that can utilize a carbon source, there is a complete
high-confidence catabolic pathway (including a transporter) just 38% of the time, and
there is a complete medium-confidence pathway 63% of the time.
Gaps may be due to:
- our ignorance of proteins' functions,
- omissions in the gene models,
- frame-shift errors in the genome sequence, or
- the organism lacks the pathway.
GapMind relies on the predicted proteins in the genome and does not search the six-frame translation. In most cases, you can search the six-frame translation by clicking on links to Curated BLAST for each step definition (in the per-step page).
For more information, see:
If you notice any errors or omissions in the step descriptions, or any questionable results, please let us know
by Morgan Price, Arkin group, Lawrence Berkeley National Laboratory