The kinetics of ribosomal peptidyl transfer revisited.
The speed of protein synthesis determines the growth rate of bacteria. Current biochemical estimates of the rate of protein elongation are small and incompatible with the rate of protein elongation in the living cell. With a cell-free system for protein synthesis, optimized for speed and accuracy, we have estimated the rate of peptidyl transfer from a peptidyl-tRNA in P site to a cognate aminoacyl-tRNA in A site at various temperatures. We have found these rates to be much larger than previously measured and fully compatible with the speed of protein elongation for E. coli cells growing in rich medium. We have found large activation enthalpy and small activation entropy for peptidyl transfer, similar to experimental estimates of these parameters for A site analogs of aminoacyl-tRNA. Our work has opened a useful kinetic window for biochemical studies of protein synthesis, bridging the gap between in vitro and in vivo data on ribosome function.
Johansson
Magnus
M
Department of Cell and Molecular Biology, BMC, Uppsala University, Box 596, S-751 24 Uppsala, Sweden.
Bouakaz
Elli
E
Lovmar
Martin
M
Ehrenberg
Måns
M
D004151:Dipeptides / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D013816:Thermodynamics; D014325:Tromethamine
D004151:Dipeptides; D012329:RNA, Bacterial; D012346:RNA, Transfer, Amino Acyl; D014325:Tromethamine; D006160:Guanosine Triphosphate