Structural studies of the YedU stress protein

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Title: Structural studies of the YedU stress protein
Author: Yonghong Zhao
Abstract: The knowledge of stress proteins is important for understanding stress response , pathology of a broad set of diseases , and the development of therapeutics . The Escherichia coli YedU stress protein , also known as Hsp31 , is highly induced upon heat shock . To obtain a better understanding for the possible molecular function of the YedU stress protein , it was expressed , purified , and crystallized . The crystal structure of YedU was determined at 2 .2 Å resolution in a multiple isomorphous replacement (MIR ) experiment . \r \nYedU monomer has an alpha /beta /alpha sandwich domain and a second smaller domain . Between the sandwich domain and the second smaller domain , there is a putative catalytic triad composed of Cys184 , His185 , and Asp213 . A metal -binding site was identified , where a zinc (II ) ion is coordinated by a 2 -His -1 -carboxylate motif composed of His85 , Glu90 , and His122 . The possible functions of the metal -binding site and the Cys184 -His185 -Asp213 triad are discussed . \r \nIt was reported that YedU has chaperone activity in vitro . YedU forms dimers in solution and the dimer interface was identified . The molecular surface of the YedU homodimer exhibits a number of solvent -exposed hydrophobic patches that are reminiscent of substrate -binding sites of molecular chaperones . To investigate the role of a central hydrophobic patch in substrate binding , four mutants were made , each replacing a hydrophobic residue with a charged residue . Compared with the wild type YedU protein , the chaperone activity of these mutants was only slightly reduced , suggesting that these residues alone do not play a dominant role in substrate binding at high temperatures .
URI: http : / /hdl .handle .net /2152 .3 /242
Date: 2004-11-12

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Structural studies of the YedU stress protein. Doctoral dissertation, The University of Texas Medical Branch. Available electronically from http : / /hdl .handle .net /2152 .3 /242 .

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