title: Electrostatic interactions play a critical role in Mycobacterium tuberculosis Hsp16.3 binding of substrate proteins.
abstract: Mycobacterium tuberculosis Hsp16.3, a member of a small heat shock protein family, has chaperone-like activity in vitro and suppresses thermally or chemically induced aggregation of proteins. The nature of the interactions between Hsp16.3 and the denatured substrate proteins was investigated. A dramatic enhancement of chaperone-like activity of Hsp16.3 upon increasing temperature was accompanied by decreased ANS-detectable surface hydrophobicity. Hsp16.3 exhibited significantly enhanced chaperone-like activity after preincubation at 100 degrees C with almost unchanged surface hydrophobicity. The interaction between Hsp16.3 and dithiothreitol-treated insulin B chains was markedly weakened in the presence of NaCl but greatly enhanced by the addition of a low-polarity alcohol, accompanied by significantly increased and decreased surface hydrophobicity, respectively. A working model for Hsp16.3 binding to its substrate proteins is proposed.
authors.affiliation: Department of Biological Science and Biotechnology and State Key Laboratory of Biomembranes and Membrane Biotechnology, Tsinghua University, Beijing 100084, PRChina.
authors.forename: Q
authors.initials: Q
authors.lastname: Mao
authors.forename: D
authors.initials: D
authors.lastname: Ke
authors.forename: Z
authors.initials: Z
authors.lastname: Chang
mesh_terms: D000438:Alcohols / Q000737:chemistry / Q000378:metabolism; D004229:Dithiothreitol / Q000737:chemistry / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D007328:Insulin / Q000737:chemistry / Q000378:metabolism*; D018832:Molecular Chaperones / Q000737:chemistry / Q000378:metabolism*; D009169:Mycobacterium tuberculosis / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D021122:Protein Subunits; D012965:Sodium Chloride / Q000737:chemistry / Q000378:metabolism; D055672:Static Electricity
chemical_list: D000438:Alcohols; D006360:Heat-Shock Proteins; D007328:Insulin; D018832:Molecular Chaperones; D021122:Protein Subunits; D012965:Sodium Chloride; D004229:Dithiothreitol