3LVL

Crystal Structure of E.coli IscS-IscU complex

Summary for 3LVL

• Entry DOI: 10.2210/pdb3lvl/pdb
• Related: 3LVJ 3LVK 3LVM
• Descriptor: Cysteine desulfurase, NifU-like protein, PYRIDOXAL-5'-PHOSPHATE, ... (4 entities in total)
• Functional Keywords: protein-protein complex, structural genomics, montreal-kingston bacterial structural genomics initiative, bsgi, transferase, fe-s cluster assembly, sulfur transfer
• Biological source: Escherichia coli; More
• Cellular location: Cytoplasm : P0A6B9
• Total number of polymer chains: 2
• Total formula weight: 61452.53

Authors

Shi, R.,Proteau, A.,Matte, A.,Cygler, M.,Montreal-Kingston Bacterial Structural Genomics Initiative (BSGI) (deposition date: 2010-02-22, release date: 2010-04-21, Last modification date: 2023-09-06)

Primary citation

Shi, R.,Proteau, A.,Villarroya, M.,Moukadiri, I.,Zhang, L.,Trempe, J.F.,Matte, A.,Armengod, M.E.,Cygler, M.
Structural basis for Fe-S cluster assembly and tRNA thiolation mediated by IscS protein-protein interactions.
Plos Biol., 8:e1000354-e1000354, 2010

PubMed Abstract: The cysteine desulfurase IscS is a highly conserved master enzyme initiating sulfur transfer via persulfide to a range of acceptor proteins involved in Fe-S cluster assembly, tRNA modifications, and sulfur-containing cofactor biosynthesis. Several IscS-interacting partners including IscU, a scaffold for Fe-S cluster assembly; TusA, the first member of a sulfur relay leading to sulfur incorporation into the wobble uridine of several tRNAs; ThiI, involved in tRNA modification and thiamine biosynthesis; and rhodanese RhdA are sulfur acceptors. Other proteins, such as CyaY/frataxin and IscX, also bind to IscS, but their functional roles are not directly related to sulfur transfer. We have determined the crystal structures of IscS-IscU and IscS-TusA complexes providing the first insight into their different modes of binding and the mechanism of sulfur transfer. Exhaustive mutational analysis of the IscS surface allowed us to map the binding sites of various partner proteins and to determine the functional and biochemical role of selected IscS and TusA residues. IscS interacts with its partners through an extensive surface area centered on the active site Cys328. The structures indicate that the acceptor proteins approach Cys328 from different directions and suggest that the conformational plasticity of a long loop containing this cysteine is essential for the ability of IscS to transfer sulfur to multiple acceptor proteins. The sulfur acceptors can only bind to IscS one at a time, while frataxin and IscX can form a ternary complex with IscU and IscS. Our data support the role of frataxin as an iron donor for IscU to form the Fe-S clusters.

PubMed: 20404999
DOI: 10.1371/journal.pbio.1000354

Experimental method

X-RAY DIFFRACTION (3 Å)