Fe‑S Cluster Biogenesis in Gram-Positive Bacteria: SufU Is a Zinc-Dependent Sulfur Transfer Protein

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 Su...

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Bibliographic Details
Published in:Biochemistry (Easton) 2014-01, Vol.53 (1), p.152-160
Main Authors: Selbach, Bruna P, Chung, Alexander H, Scott, Aubrey D, George, Simon J, Cramer, Stephen P, Dos Santos, Patricia C
Format: Article
Language:English
Subjects:
Bacillus subtilis
Bacillus subtilis - enzymology
Bacterial Proteins - metabolism
Carbon-Sulfur Lyases - metabolism
Cysteine - metabolism
Iron-Sulfur Proteins - biosynthesis
Iron-Sulfur Proteins - metabolism
Sulfotransferases - metabolism
Sulfur - metabolism
Sulfurtransferases - metabolism
Zinc - metabolism
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Summary: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 (K a = 1017 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.
ISSN:0006-2960
1520-4995
DOI:10.1021/bi4011978