1u4n
From Proteopedia
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Crystal Structure Analysis of the M211S/R215L EST2 mutant
Overview
Esterase 2 (EST2) from the thermophilic eubacterium Alicyclobacillus, acidocaldarius is a thermostable serine hydrolase belonging to the H group, of the esterase/lipase family. This enzyme hydrolyzes monoacylesters of, different acyl-chain length and various compounds with industrial, interest. EST2 displays an optimal temperature at 70 degrees C and maximal, activity with pNP-esters having acyl-chain bearing from six to eight, carbon atoms. EST2 mutants with different substrate specificity were also, designed, generated by site-directed mutagenesis, and biochemically, characterized. To better define at structural level the enzyme reaction, mechanism, a crystallographic analysis of one of these mutants, namely, M211S/R215L, was undertaken. Here we report its three-dimensional, structure at 2.10A resolution. Structural analysis of the enzyme revealed, an unexpected dimer formation as a consequence of a domain-swapping event, involving its N-terminal region. This phenomenon was absent in the case of, the enzyme bound to an irreversible inhibitor having optimal substrate, structural features. A detailed comparison of the enzyme structures before, and following binding to this molecule showed a movement of the N-terminal, helices resulting from a trans-cis isomerization of the F37-P38 peptide, bond. These findings suggest that this carboxylesterase presents two, distinct structural arrangements reminiscent of the open and closed forms, already reported for lipases. Potential biological implications associated, with the observed quaternary reorganization are here discussed in light of, the biochemical properties of other lipolytic members of the H group.
About this Structure
1U4N is a Single protein structure of sequence from Alicyclobacillus acidocaldarius with SO4 as ligand. Active as Carboxylesterase, with EC number 3.1.1.1 Full crystallographic information is available from OCA.
Reference
The crystal structure of an EST2 mutant unveils structural insights on the H group of the carboxylesterase/lipase family., De Simone G, Menchise V, Alterio V, Mandrich L, Rossi M, Manco G, Pedone C, J Mol Biol. 2004 Oct 8;343(1):137-46. PMID:15381425
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