GapMind for catabolism of small carbon sources


citrate catabolism in Skermanella stibiiresistens SB22

Best path

citM, acn, icd


Overview: Citrate is utilized via ATP-citrate lyase (link) or by oxidation to 2-oxoglutarate (part of the the TCA cycle, link). MetaCyc does not explicitly represent the TCA cycle as a means for catabolizing citrate, but it is expected to function under respiratory conditions. Fitness data confirms that in diverse bacteria, ATP-citrate lyase is not necessary for aerobic utilization of citrate.

20 steps (12 with candidates)

Or see definitions of steps

Step Description Best candidate 2nd candidate
citM citrate:cation:H+ symporter CitM N825_RS15705
acn aconitase N825_RS22455 N825_RS26795
icd isocitrate dehydrogenase N825_RS28395 N825_RS14275
Alternative steps:
cimH citrate:H+ symporter CimH
cit1 citrate:H+ symporter Cit1
citA citrate:H+ symporter CitA N825_RS22445 N825_RS05255
citD citrate lyase, acyl carrier component CitD
citE citrate lyase, citryl-ACP lyase component CitE N825_RS05730 N825_RS09635
citF citrate lyase, citrate-ACP transferase component CitF
citS citrate:Na+ symporter CitS
citT citrate:succinate antiporter CitT
citW citrate exchange transporter CitW (with lactate or acetate)
fecB ferric citrate ABC transporter, substrate-binding component FecB
fecC ferric citrate ABC transporter, permease component 1 (FecC) N825_RS24115 N825_RS26560
fecD ferric citrate ABC transporter, permease component 2 (FecD) N825_RS24115 N825_RS29485
fecE ferric citrate ABC transporter, ATPase component FecE N825_RS26550 N825_RS29480
SLC13A5 citrate:Na+ symporter N825_RS16135
tctA citrate/Na+ symporter, large transmembrane component TctA N825_RS25880 N825_RS30560
tctB citrate/Na+ symporter, small transmembrane component TctB N825_RS30555
tctC citrate/Na+ symporter, substrate-binding component TctC N825_RS11955 N825_RS30550

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 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:

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:

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:

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