1ecx
From Proteopedia
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NIFS-LIKE PROTEIN
Overview
NifS-like proteins are ubiquitous, homodimeric, proteins which belong to, the alpha-family of pyridoxal-5'-phoshate dependent enzymes. They are, proposed to donate elementary sulphur, generated from cysteine, via a, cysteinepersulphide intermediate during iron sulphur cluster biosynthesis, an important albeit not well understood process. Here, we report on the, crystal structure of a NifS-like protein from the hyperthermophilic, bacterium Thermotoga maritima (tmNifS) at 2.0 A resolution. The tmNifS is, structured into two domains, the larger bearing the, pyridoxal-5'-phosphate-binding active site, the smaller hosting the active, site cysteine in the middle of a highly flexible loop, 12 amino acid, residues in length. Once charged with sulphur the loop could possibly, deliver S(0) directly to regions far remote from the protein. Based on the, three-dimensional structures of the native as well as the substrate, complexed form and on spectrophotometric results, a mechanism of sulphur, activation is proposed. The His99, which stacks on top of the, pyridoxal-5'-phosphate co-factor, is assigned a crucial role during the, catalytic cycle by acting as an acid-base catalyst and is believed to have, a pK(a) value depending on the co-factor redox state.
About this Structure
1ECX is a Single protein structure of sequence from Thermotoga maritima with PLP and CYS as ligands. Full crystallographic information is available from OCA.
Reference
Crystal structure of a NifS-like protein from Thermotoga maritima: implications for iron sulphur cluster assembly., Kaiser JT, Clausen T, Bourenkow GP, Bartunik HD, Steinbacher S, Huber R, J Mol Biol. 2000 Mar 24;297(2):451-64. PMID:10715213
Page seeded by OCA on Sat Nov 24 22:03:24 2007
