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.
Or see definitions of steps
| Step | Description | Best candidate | 2nd candidate |
|---|---|---|---|
| tctA | citrate/Na+ symporter, large transmembrane component TctA | DK187_RS04420 | DK187_RS12740 |
| tctB | citrate/Na+ symporter, small transmembrane component TctB | DK187_RS04425 | DK187_RS02895 |
| tctC | citrate/Na+ symporter, substrate-binding component TctC | DK187_RS04430 | DK187_RS12750 |
| acn | aconitase | DK187_RS13240 | DK187_RS10545 |
| icd | isocitrate dehydrogenase | DK187_RS08125 | DK187_RS13260 |
| Alternative steps: | |||
| cimH | citrate:H+ symporter CimH | DK187_RS04705 | |
| cit1 | citrate:H+ symporter Cit1 | ||
| citA | citrate:H+ symporter CitA | ||
| citD | citrate lyase, acyl carrier component CitD | ||
| citE | citrate lyase, citryl-ACP lyase component CitE | ||
| citF | citrate lyase, citrate-ACP transferase component CitF | ||
| citM | citrate:cation:H+ symporter CitM | ||
| citS | citrate:Na+ symporter CitS | DK187_RS04705 | |
| citT | citrate:succinate antiporter CitT | ||
| citW | citrate exchange transporter CitW (with lactate or acetate) | DK187_RS04705 | |
| fecB | ferric citrate ABC transporter, substrate-binding component FecB | DK187_RS07340 | |
| fecC | ferric citrate ABC transporter, permease component 1 (FecC) | DK187_RS07335 | DK187_RS10995 |
| fecD | ferric citrate ABC transporter, permease component 2 (FecD) | DK187_RS07330 | DK187_RS20160 |
| fecE | ferric citrate ABC transporter, ATPase component FecE | DK187_RS07325 | DK187_RS11705 |
| SLC13A5 | citrate:Na+ symporter | ||
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.
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:
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