Subsystem: At5g37530 (CsdL protein family)

This subsystem's description is:

Hypothesis 1: At5g37530 (plant homolog of the bacterial CsdL/YgdL protein family) is an additional subunit of plant Cysteine desulfurase (CDS) - see details below and under "Illustrations" Tab (in 2 separate slides). Hypothesis 2: this CDS type is involved in some type of tRNA//sRNA S-modification. These predictions are based on the following observations:

1. At5g37530 belongs to COG1179, which shares similarity with ubiquitin activating enzyme E1 and members of the bacterial ThiF/MoeB/HesA family.

2. COG1179 members occur in about a quarter of analyzed bacterial genomes (in ~220 out of 860, assigned with variant code [1]). This gene family is represented in Firmicutes and Gammaproteobacteria (the fact that homologs are present in well studied organisms can facilitate it's analysis). In eukaryotes - only in fungi and plants, do NOT occur in animals (in agreement with differences in sulfur metabolism)

3. In nearly all prokaryotic genomes where they occur, the At5g37530 homologs co-localize with Cysteine desulfurase of specific type: CsdA-CsdE (EC 2.8.1.7) and with yet "unclassified" CDS, but NOT with other types of Cysteine desulfurase: IscS, nifS or SufS. The CsdA-CsdE desulfurase is believed to be “simple”: only 2 proteins are known to be involved, while other types of CDSs are associated wit additional proteins required for function (see nif, isc, suf gene clusters). Can it be that COG1179 proteins are in fact subunits (or facilitators) of CsdA-CsdE type desulfurase?

4. Other common neighbors of COG1179-encoding genes in prokaryotic genomes (especially in Firmicuts) are various tRNA synthetases, D-tyrosyl-tRNA(Tyr) deacylase, as well as small non-coding RNAs: 6S smRNA and tRNA-Met, which might indicate potential involvement of this type of CDS (and COG1179) in some type of tRNA//sRNA S-modification

5. Expression profile of At5g37530 in Arabidopsis is compatible with it being a household gene: expression at constant (low) level in all types of tissues and under all conditions tested.

6. Cellular localization unknown

7. Since At5g37530 and it’s bacterial homologs share homology with ubiquitin-activating enzyme E1, we can speculate that this protein family forms a similar persulfidic sulfur relay (based on Kessler, 2006) for an unknown acceptor (ultimately involved in tRNA//sRNA S-modification??). If this hypothesis was true, it would be interesting to look for COG1179's counterpart – possibly a ThiS/MoaD/CysO family protein with the C-terminal Gly-Gly sequence (see potential leads based on yeast protein-protein interaction data under "Illustrations" Tab of this SS).

References:

Loiseau L, Ollagnier-de Choudens S, Lascoux D, Forest E, Fontecave M, Barras F. Analysis of the heteromeric CsdA-CsdE cysteine desulfurase, assisting Fe-S cluster biogenesis in Escherichia coli.
J Biol Chem. 2005 Jul 22;280(29):26760-9. PMID: 20054882

Kessler D. Enzymatic activation of sulfur for incorporation into biomolecules in prokaryotes. FEMS Microbiol Rev. 2006 Nov;30(6):825-40. Review. PMID: 17064282

For more information, please check out the description and the additional notes tabs, below

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