PDBsum entry 3lvm

Transferase

PDB id: 3lvm

Contents

Protein chains

393 a.a. *

Ligands

PLP ×2

Waters ×310

* Residue conservation analysis

PDB id:

3lvm

Name:

Transferase

Title:

Crystal structure of e.Coli iscs

Structure:

Cysteine desulfurase. Chain: a, b. Engineered: yes

Source:

Escherichia coli. Organism_taxid: 155864. Strain: o157:h7 edl933. Gene: iscs. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.05Å R-factor: 0.200 R-free: 0.238

Authors:

R.Shi,A.Proteau,A.Matte,M.Cygler,Montreal-Kingston Bacterial Structural Genomics Initiative (Bsgi)

Key ref:

R.Shi et al. (2010). Structural basis for Fe-S cluster assembly and tRNA thiolation mediated by IscS protein-protein interactions. Plos Biol, 8, e1000354. PubMed id: 20404999

Date:

22-Feb-10 Release date: 21-Apr-10

Protein chains

P0A6B9  (ISCS_ECO57) -  Cysteine desulfurase IscS from Escherichia coli O157:H7

Seq: 404 a.a.

Struc: 393 a.a.

Enzyme reactions

• Enzyme class: E.C.2.8.1.7 - cysteine desulfurase.
• Reaction: (sulfur carrier)-H + L-cysteine = (sulfur carrier)-SH + L-alanine
• Cofactor: Pyridoxal 5'-phosphate

Pyridoxal 5'-phosphate (Bound ligand (Het Group name = PLP) matches with 93.75% similarity)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

Plos Biol 8:e1000354 (2010)

PubMed id: 20404999

Structural basis for Fe-S cluster assembly and tRNA thiolation mediated by IscS protein-protein interactions.

R.Shi, A.Proteau, M.Villarroya, I.Moukadiri, L.Zhang, J.F.Trempe, A.Matte, M.E.Armengod, M.Cygler.

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.