title: Fe-S cluster biogenesis in Gram-positive bacteria: SufU is a zinc-dependent sulfur transfer protein.
abstract: The biosynthesis of Fe-S clusters in Bacillus subtilis and other Gram-positive bacteria is catalyzed by the SufCDSUB system. The first step in this pathway involves the sulfur mobilization from the free amino acid cysteine to a sulfur acceptor protein SufU via a PLP-dependent cysteine desulfurase SufS. In this reaction scheme, the formation of an enzyme S-covalent intermediate is followed by the binding of SufU. This event leads to the second half of the reaction where a deprotonated thiol of SufU promotes the nucleophilic attack onto the persulfide intermediate of SufS. Kinetic analysis combined with spectroscopic methods identified that the presence of a zinc atom tightly bound to SufU (Ka = 10(17) M(-1)) is crucial for its structural and catalytic competency. Fe-S cluster assembly experiments showed that despite the high degree of sequence and structural similarity to the ortholog enzyme IscU, the B. subtilis SufU does not act as a standard Fe-S cluster scaffold protein. The involvement of SufU as a dedicated agent of sulfur transfer, rather than as an assembly scaffold, in the biogenesis of Fe-S clusters in Gram-positive microbes indicates distinct strategies used by bacterial systems to assemble Fe-S clusters.
authors: Department of Chemistry, Wake Forest University , Winston-Salem, North Carolina, United States.
authors: Bruna P
authors: BP
authors: Selbach
authors: Alexander H
authors: AH
authors: Chung
authors: Aubrey D
authors: AD
authors: Scott
authors: Simon J
authors: SJ
authors: George
authors: Stephen P
authors: SP
authors: Cramer
authors: Patricia C
authors: PC
authors: Dos Santos
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology*; D001426:Bacterial Proteins / Q000378:metabolism*; D013437:Carbon-Sulfur Lyases / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000096:biosynthesis* / Q000378:metabolism; D015238:Sulfotransferases / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism; D013466:Sulfurtransferases / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D007506:Iron-Sulfur Proteins; D013455:Sulfur; D013466:Sulfurtransferases; D015238:Sulfotransferases; D013437:Carbon-Sulfur Lyases; C080546:cysteine desulfurase; D015032:Zinc; D003545:Cysteine