title: Increased efficiency of GroE-assisted protein folding by manganese ions.
abstract: This study addresses the role of ATP-bound and free Mg2+ and Mn2+ ions in the activation and modulation of chaperonin-assisted refolding of urea-denatured malate dehydrogenase. As compared with Mg2+, Mn2+ ions caused a significant increase in the rate of GroE-assisted malate dehydrogenase refolding and, concomitantly, a decrease in the rate of ATP hydrolysis. Moreover, Mn2+ increases the affinity of GroES for GroEL, even in the presence of saturating amounts of Mg2+. Chemical cross-linking showed that lower concentrations of Mn-ATP as compared with Mg-ATP are needed to form both asymmetric GroEL14GroES7 and symmetric GroEL14(GroES7)2 particles. The manganese-dependent increase in the rate of protein folding concurred with a specific increase in the amount of symmetric GroEL14-(GroES7)2 particles detected in a chaperonin solution. Thus, Mn2+ is a cofactor that can markedly increase the efficiency of the chaperonin reaction in vitro. Mn2+ ions can serve as an important tool for analyzing the molecular mechanism and the structure of chaperonins.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D018835:Chaperonin 10 / Q000378:metabolism; D018834:Chaperonin 60 / Q000378:metabolism; D018833:Chaperonins; D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008291:Malate Dehydrogenase / Q000737:chemistry* / Q000187:drug effects; D008345:Manganese / Q000494:pharmacology*; D008929:Mitochondria, Heart / Q000201:enzymology; D017510:Protein Folding; D013552:Swine
chemical_list: D001426:Bacterial Proteins; D018835:Chaperonin 10; D018834:Chaperonin 60; D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; C028715:GroE protein, E coli; D006360:Heat-Shock Proteins; D008345:Manganese; D000255:Adenosine Triphosphate; D008291:Malate Dehydrogenase; D018833:Chaperonins; D008274:Magnesium