Professor Joachim Weber
Department of Cell Biology and Biochemistry
Texas Tech University, Univ. Health Science Center
Lubbock, TX

Monday, March 29, 2004
3:00 pm (CT)
3269 Beckman Institute

Abstract

ATP synthase uses a unique mechanism, subunit rotation, to couple ATP synthesis/ hydrolysis and transmembrane proton transport. The molecular mechanism was investigated by a combination of tryptophan fluorescence spectroscopy and site-directed mutagenesis. We could demonstrate that all three catalytic sites have to be filled for ATP hydrolysis to occur (“trisite catalysis”). During steady-state ATP hydrolysis two of the sites are filled with ADP and one with ATP. Mutational analysis was used to determine the coordination of the essential Mg2+ ion and the structure of the transition state complex. Recently, we examined protein-protein interactions in the stator stalk, which holds the enzyme together during rotation. Hypotheses of how ATP binding and/or hydrolysis might drive subunit rotation will be discussed.

Tea and coffee will be served in R3151 Beckman Institute at 2:15pm.