Cysteine is not the sulfur source for iron-sulfur cluster and methionine biosynthesis in the methanogenic archaeon Methanococcus maripaludis.
Summary of "Cysteine is not the sulfur source for iron-sulfur cluster and methionine biosynthesis in the methanogenic archaeon Methanococcus maripaludis."
Three multi-protein systems are known for iron-sulfur (Fe-S) cluster biogenesis in bacteria and eukaryotes: the NIF (nitrogen fixation), the ISC (iron-sulfur cluster), and the SUF (mobilization of sulfur) systems. In all three, cysteine is the physiological sulfur source, and the sulfur is transferred from cysteine desulfurase through a persulfidic intermediate to a scaffold protein. However, the biochemical nature of the sulfur source for Fe-S cluster assembly in archaea is not known, and many archaea lack homologs of cysteine desulfurases. Methanococcus maripaludis is a methanogenic archaeon that contains a high amount of protein-bound Fe-S clusters (45 nmol/mg protein). Cysteine in this archaeon is synthesized primarily via the tRNA-dependent SepRS/SepCysS pathway. When a DeltasepS mutant (a cysteine auxotroph) was grown with (34)S-labeled sulfide and unlabeled cysteine, < 8% of the cysteine, > 92% of the methionine, and > 87% of the sulfur in the Fe-S clusters in proteins was labeled, suggesting that the sulfur in methionine and Fe-S clusters was derived predominantly from exogenous sulfide instead of cysteine. Therefore, this investigation challenges the prior knowledge that cysteine is always the sulfur source for Fe-S cluster biosynthesis in vivo and suggests that Fe-S clusters are derived from sulfide in organisms living in sulfide-rich habitats.
Affiliation
University of Georgia, United States;
Journal Details
This article was published in the following journal.
Name: The Journal of biological chemistry
ISSN: 1083-351X
Pages:
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20709756
- DOI: http://dx.doi.org/10.1074/jbc.M110.152447
Medical and Biotech [MESH] Definitions
Rubredoxins
A class of iron-sulfur proteins that contains one iron coordinated to the sulfur atom of four cysteine residues. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)
Iron-sulfur Proteins
A group of proteins possessing only the iron-sulfur complex as the prosthetic group. These proteins participate in all major pathways of electron transport: photosynthesis, respiration, hydroxylation and bacterial hydrogen and nitrogen fixation.
Sulfur-sulfur Bond Isomerases
Enzymes that catalyze the transposition of a sulfur-sulfur bond. EC 5.3.4.
Sulfite Reductase (ferredoxin)
A FERREDOXIN-dependent oxidoreductase that is primarily found in PLANTS where it plays an important role in the assimilation of SULFUR atoms for the production of CYSTEINE and METHIONINE.
Sulfur
An element that is a member of the chalcogen family. It has an atomic symbol S, atomic number 16, and atomic weight 32.066. It is found in the amino acids cysteine and methionine.
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