Finding step mglB for D-glucose catabolism in Sphingobium czechense LL01
No candidates for mglB: glucose ABC transporter, substrate-binding component
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 mglB
- Curated sequence P0AEE5: D-galactose-binding periplasmic protein DGAL aka MglB aka B2150, component of Galactose/glucose (methyl galactoside) porter. D-galactose/methyl-galactoside ABC transporter periplasmic binding protein. D-galactose/methyl-galactoside ABC transporter periplasmic binding protein
- Curated sequence P25548: CVE1 aka ChvE aka ATU2348 aka AGR_C_4267, component of Multiple sugar (arabinose, xylose, galactose, glucose, fucose) putative porter
- Curated sequence GFF3639: glucose transporter, periplasmic substrate-binding component
- Curated sequence G4FGN5: LacI family transcriptional regulator, component of Glucose porter. Also bind xylose (Boucher and Noll 2011). Induced by glucose (Frock et al. 2012). Directly regulated by glucose-responsive regulator GluR
- Ignore hits to P54083 when looking for 'other' hits (Multiple sugar-binding periplasmic protein SbpA; Sugar-binding protein A)
- Comment: mglB (b2150) from E. coli (P0AEE5; 332 a.a.), chvE, or TC 3.A.1.2.20 / G4FGN5 in Thermotoga (343 a.a.) [absent from Haloferax]. Ignore SBPA_AZOBR / P54083 from Azospirillum, whose substrate specificity is uncertain.
Or cluster all characterized mglB 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