title: The small heat shock protein IbpA of Escherichia coli cooperates with IbpB in stabilization of thermally aggregated proteins in a disaggregation competent state.
abstract: The small heat shock proteins are ubiquitous stress proteins proposed to increase cellular tolerance to heat shock conditions. We isolated IbpA, the Escherichia coli small heat shock protein, and tested its ability to keep thermally inactivated substrate proteins in a disaggregation competent state. We found that the presence of IbpA alone during substrate thermal inactivation only weakly influences the ability of the bi-chaperone Hsp70-Hsp100 system to disaggregate aggregated substrate. Similar minor effects were observed for IbpB alone, the other E. coli small heat shock protein. However, when both IbpA and IbpB are simultaneously present during substrate inactivation they efficiently stabilize thermally aggregated proteins in a disaggregation competent state. The properties of the aggregated protein substrates are changed in the presence of IbpA and IbpB, resulting in lower hydrophobicity and the ability of aggregates to withstand sizing chromatography conditions. IbpA and IbpB form mixed complexes, and IbpA stimulates association of IbpB with substrate.
authors.affiliation: Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology, University of Gdansk, 80-822 Gdansk, Kladki 24, Poland.
authors.forename: Marlena
authors.initials: M
authors.lastname: Matuszewska
authors.forename: Dorota
authors.initials: D
authors.lastname: Kuczyńska-Wiśnik
authors.forename: Ewa
authors.initials: E
authors.lastname: Laskowska
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Liberek
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry; D001671:Biochemistry / Q000379:methods; D002845:Chromatography; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism*; D006358:Hot Temperature; D008156:Luciferases / Q000378:metabolism; D018832:Molecular Chaperones / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012685:Sepharose / Q000737:chemistry; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C097578:IbpA protein, E coli; C097579:IbpB protein, E coli; D018832:Molecular Chaperones; D012685:Sepharose; D008156:Luciferases