ethanol catabolism in Azospirillum brasilense Sp245

GapMind for catabolism of small carbon sources

ethanol catabolism in Azospirillum brasilense Sp245

Best path

Also see fitness data for the top candidates

Rules

Overview: Ethanol can pass through biological membranes, so no transporter is required. Ethanol degradation in GapMind is based on MetaCyc pathways ethanol degradation I (oxidation to acetyl-CoA, link) and II (oxidation to acetate and activation, link). Pathways III (with ethanol monooxygenase, link) and IV (with ethanol peroxidase, link) are not reported to occur in prokaryotes and are not included.

all: etoh-dh and acetaldehyde-degradation

Comment: Ethanol is consumed by oxidation to acetaldehyde

acetaldehyde-degradation:

ald-dh-CoA
or adh and acs
or adh, ackA and pta
Comment: Acetaldehyde can be oxidized to acetyl-CoA, or oxidized to acetate and activated to acetyl-CoA by either acetyl-CoA synthetase (acs) or by acetate kinase (ackA) and phosphate acetyltransferase (pta).

etoh-dh:

etoh-dh-nad
or etoh-dh-c
or etoh-dh-qn
Comment: Three types of ethanol dehydrogenases: NAD(P) dependent, cytochrome c dependent, or quinone dependent.

etoh-dh-qn: adhAqn, adhBqn and adhSqn

Comment: Bacterial quinone-dependent enzymes (EC 1.1.5.5) have 3 subunits.

10 steps (9 with candidates)

Or see definitions of steps

Step	Description	Best candidate	2nd candidate
etoh-dh-nad	ethanol dehydrogenase (NAD(P))	AZOBR_RS32240	AZOBR_RS16515
adh	acetaldehyde dehydrogenase (not acylating)	AZOBR_RS22315	AZOBR_RS26825
acs	acetyl-CoA synthetase, AMP-forming	AZOBR_RS00270	AZOBR_RS06340
Alternative steps:
ackA	acetate kinase	AZOBR_RS12495	AZOBR_RS04605
adhAqn	ethanol dehydrogenase (quinone), subunit I	AZOBR_RS12740	AZOBR_RS24625
adhBqn	ethanol dehydrogenase (quinone), subunit II	AZOBR_RS04080
adhSqn	ethanol dehydrogenase (quinone), subunit III
ald-dh-CoA	acetaldehyde dehydrogenase, acylating	AZOBR_RS32240	AZOBR_RS32475
etoh-dh-c	ethanol dehydrogenase (cytochrome c)	AZOBR_RS27870	AZOBR_RS12740
pta	phosphate acetyltransferase	AZOBR_RS04600	AZOBR_RS12500

Confidence: high confidence medium confidence low confidence
transporter – transporters and PTS systems are shaded because predicting their specificity is particularly challenging.

This GapMind analysis is from Sep 17 2021. The underlying query database was built on Sep 17 2021.

Downloads

Candidates (tab-delimited)
Steps (tab-delimited)
Rules (tab-delimited)
Protein sequences (fasta format)
Organisms (tab-delimited)
SQLite3 databases

Related tools

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:

the paper from 2019 on GapMind for amino acid biosynthesis
the paper from 2022 on GapMind for carbon sources
the source code
instructions for running GapMind on your computer

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

GapMind for catabolism of small carbon sources