The Identification of a Novel Protein Involved in Molybdenum Cofactor Biosynthesis in Escherichia coli

Abstract

Background: In Moco biosynthesis, sulfur is transferred from L-cysteine to MPT synthase, catalyzing the conversion of cPMP to MPT. Results: The rhodanese-like protein YnjE is a novel protein involved in Moco biosynthesis. Conclusion: YnjE enhances the rate of conversion of cPMP to MPT and interacts with MoeB and IscS. Significance: To understand the mechanism of sulfur transfer and the role of rhodaneses in the cell.

The Sulfur Carrier Protein TusA Has a Pleiotropic Role in Escherichia coli That Also Affects Molybdenum Cofactor Biosynthesis*

“…The lysate was obtained by sonication. The total MPT content of the strains was determined by form A detection as described previously (5).…”

“…The direct sulfur donor for MoaD is the IscS protein, which generates the thiocarboxylate group on MoaD in conjunction with MoeB (25). YnjE is also involved in this step, making the sulfur transfer reaction from IscS more specific (5). To test whether TusA is additionally involved in the sulfur transfer reaction from IscS to MoaD, we analyzed the sulfuration level of MoaD isolated from a ⌬tusA mutant.…”

“…The initial sulfur mobilization step is catalyzed by IscS forming a protein-bound persulfide after the conversion of L-cysteine to L-alanine (4). IscS delivers the sulfur to several sulfur-accepting proteins such as IscU, TusA, and ThiI and, as shown recently, to rhodanese-like proteins such as YnjE (5,6), thereby providing sulfur for different metabolic pathways like the assembly of FeS cluster, thiamine, biotin, and lipoic acid, tRNA modification, or molybdenum cofactor (Moco) biosynthesis. Recent studies by Shi et al (7) map the different binding sites for proteins that interact with IscS.…”

“…It has been shown that MoeB solely activates the C terminus of MoaD by the formation of an acyl-adenylate, and the L-cysteine desulfurase IscS in its persulfide-bound form has been identified as the primary physiological sulfur-donating enzyme for the generation of thiocarboxylate on MPT synthase (24,25). Recently, it has been shown that the rhodanese-like protein YnjE works in conjunction with IscS to make the sulfur transfer to MoaD more specific (5).…”

Rhodanese Functions as Sulfur Supplier for Key Enzymes in Sulfur Energy Metabolism

“…Despite numerous studies, the physiological role of rhodaneses as well as their physiological substrates remain unclear and are still widely debated. It has been proposed that they accomplish essential cell functions as they may be involved in the maintenance of redox homeostasis (20), in the elimination of toxic cyanide (21), and in the biosynthesis of several other cellular metabolites such as vitamins, enzymes, and cofactors that include a step of sulfur transfer (22)(23)(24)(25).…”