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Glu257 in GroEL is a sensor involved in coupling polypeptide substrate binding to stimulation of ATP hydrolysis
Author(s) -
Danziger Oded,
Shimon Liat,
Horovitz Am
Publication year - 2006
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.062100606
Subject(s) - groel , chaperonin , atp hydrolysis , atpase , biochemistry , alanine , chemistry , hydrolysis , chaperone (clinical) , biophysics , stimulation , enzyme , protein folding , biology , amino acid , escherichia coli , gene , medicine , pathology , neuroscience
The ATPase activity of many types of molecular chaperones is stimulated by polypeptide substrate binding via molecular mechanisms that are, for the most part, unknown. Here, we report that such stimulation of the ATPase activity of GroEL is abolished when its conserved apical domain residue Glu257 is replaced by alanine. This mutation is also found to convert the ATPase profile of GroEL, a group I chaperonin, into one that is characteristic of group II chaperonins. Steady‐state and transient kinetic analysis indicate that both effects are due, at least in part, to a reduction of the affinity of GroEL for ADP. This finding indicates that nonfolded proteins stimulate ATP hydrolysis by accelerating the off‐rate of the ADP formed, thereby allowing more rapid cycles of ATP binding and hydrolysis.