The CsdA cysteine desulphurase promotes Fe/S biogenesis  by recruiting Suf components and participates to a new  sulphur transfer pathway by recruiting CsdL (ex-YgdL),  a ubiquitin-modifying-like protein.
Cysteine desulphurases are primary sources of sulphur that can eventually be used for Fe/S biogenesis or thiolation of various cofactors and tRNA. Escherichia coli contains three such enzymes, IscS, SufS and CsdA. The importance of IscS and SufS in Fe/S biogenesis is well established. The physiological role of CsdA in contrast remains uncertain. We provide here additional evidences for a functional redundancy between the three cysteine desulphurases in vivo. In particular, we show that a deficiency in isoprenoid biosynthesis is the unique cause of the lethality of the iscS sufS mutant. Moreover, we show that CsdA is engaged in two separate sulphur transfer pathways. In one pathway, CsdA interacts functionally with SufE-SufBCD proteins to assist Fe/S biogenesis. In another pathway, CsdA interacts with CsdE and a newly discovered protein, which we called CsdL, resembling E1-like proteins found in ubiquitin-like modification systems. We propose this new pathway to allow synthesis of an as yet to be discovered thiolated compound.
Trotter
Valentine
V
Laboratoire de Chimie Bactérienne, UPR-CNRS 9043, IFR 88 Institut de Microbiologie de la Méditerranée, CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
Vinella
Daniel
D
Loiseau
Laurent
L
Ollagnier de Choudens
Sandrine
S
Fontecave
Marc
M
Barras
Frédéric
F
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D019677:Artificial Gene Fusion; D053898:Biosynthetic Pathways; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D053487:DEAD-box RNA Helicases / Q000378:metabolism*; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D017930:Genes, Reporter; D007501:Iron / Q000378:metabolism*; D008190:Lyases / Q000235:genetics / Q000378:metabolism; D016254:Mutagenesis, Insertional; D011485:Protein Binding; D025941:Protein Interaction Mapping; D013455:Sulfur / Q000378:metabolism*; D044764:Ubiquitin-Activating Enzymes / Q000378:metabolism*; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
D002352:Carrier Proteins; C547583:CsdL protein, E coli; D004251:DNA Transposable Elements; D029968:Escherichia coli Proteins; C503794:Suf E protein, E coli; C498860:SufB protein, E coli; D013455:Sulfur; D007501:Iron; D001616:beta-Galactosidase; D000251:Adenosine Triphosphatases; C088840:deaD protein, E coli; C507755:SufC protein, E coli; D053487:DEAD-box RNA Helicases; D008190:Lyases; C034278:selenocysteine lyase; D044764:Ubiquitin-Activating Enzymes