Ribose 2'-hydroxyl groups in the 5' strand of the acceptor arm of P-site tRNA are not essential for EF-G catalyzed translocation.
The coupled movement of tRNA-mRNA complex through the ribosome is a fundamental step during the protein elongation process. We demonstrate that the ribosome will translocate a P-site-bound tRNA(Met) with a break in the phosphodiester backbone between positions 17 and 18 in the D-loop. Crystallographic data showed that the acceptor arms of P- and E-site tRNA interact extensively with the ribosomal large subunit. Therefore, we used this fragmented P-site-bound tRNA(Met) to investigate the contributions of single 2'-hydroxyl groups in the 5' strand of the acceptor arm for translocation into the ribosomal E-site. EF-G-dependent translocation of the tRNAs was monitored using a toeprinting assay and a fluorescence-based rapid kinetic method. Surprisingly, our results show that none of the 2'-hydroxyl groups in the 5' strand of the acceptor arm of P-site-bound tRNA(Met) between positions 1-17 play a critical role during translocation. This suggests that either these 2'-hydroxyl groups are not important for translocation or they are redundant and the three-dimensional shape of the P-site tRNA is more important for translocation.
Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0314, USA.
Jason S
JS
Feinberg
Simpson
S
Joseph
D001692:Biological Transport; D002384:Catalysis; D004591:Electrophoresis, Polyacrylamide Gel; D005453:Fluorescence; D007700:Kinetics; D020653:Peptide Elongation Factor G / Q000378:metabolism*; D012358:RNA, Transfer, Met / Q000737:chemistry / Q000378:metabolism*; D012266:Ribose / Q000737:chemistry*
D020653:Peptide Elongation Factor G; D012358:RNA, Transfer, Met; D012266:Ribose