Mechanism of activation of Saccharomyces cerevisiae calcineurin by Mn2+.
Saccharomyces cerevisiae calcineurin (CN) consists of a catalytic subunit CNA1 or CNA2 and a regulatory subunit CNB1. The kinetics of activation of yeast CN holoenzymes and their catalytic domains by Mn2+ were investigated. We report that the in vitro phosphatase reaction activated by Mn2+ typically has a pronounced initial lag phase caused by slow conformational rearrangement of the holoenzyme-Mn2+. A similar lag phase was detected using just the catalytic domain of yeast CN, indicating that the slowness of Mn2+-induced conformational change of CN results from a rearrangement within the catalytic domain. The Mn2+-activation of CN was reversible. The dissociation constant of the CN heterodimer containing the CNA2 subunit in the presence of Mn2+ was 3-fold higher than that of CN containing the CNA1 subunit and that of the catalytic domains of CNA1 and CNA2, pointing to differences between the residues surrounding the Mn2+-binding sites of CNA1 and CNA2.
Ren
Yan
Y
Department of Biochemistry and Molecular Biology, Beijing Normal University, Beijing Key Laboratory, Beijing 100875, P.R. China.
Wang
Zhi-Xin
ZX
Wei
Qun
Q
D019703:Calcineurin / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D020134:Catalytic Domain / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004926:Escherichia coli / Q000235:genetics; D020035:Holoenzymes / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013050:Spectrometry, Fluorescence
D020035:Holoenzymes; D011994:Recombinant Proteins; D019703:Calcineurin; D008274:Magnesium