Finding step nagX for D-glucosamine (chitosamine) catabolism in Cronobacter universalis NCTC 9529
No candidates for nagX: transmembrane glucosamine N-acetyltransferase NagX
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 nagX
- UniProt sequence A0KZW6: RecName: Full=DUF5009 domain-containing protein {ECO:0000259|Pfam:PF16401};
- UniProt sequence A1S448: RecName: Full=DUF5009 domain-containing protein {ECO:0000259|Pfam:PF16401};
- UniProt sequence L0FVP4: RecName: Full=DUF1624 domain-containing protein {ECO:0000259|Pfam:PF07786};
- Comment: These NagX proteins are distantly related to human HGSNAT (Q68CP4), which is a transmembrane acetyl-CoA:alpha-glucosaminide N-acetyltransferase. Genetic data suggests that these bacterial homologs are involved in glucosamine utilization, but not as a transporter -- N-acetylglucosamine utilization genes are also involved. So, they appear to be transmembrane N-acetyltransferases for glucosamine. The key histidine which holds the acetyl group as it passes through the membrane (His269 in NG_009552.1, or His297 in Q68CP4) is conserved in these proteins. The bacterial proteins with clear evidence for this role are: Shewana3_3111 (A0KZW6), Sama_0947 (A1S448), and Echvi_1106 (L0FVP4).
Or cluster all characterized nagX 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