A Conserved Proline Triplet in Val-tRNA Synthetase and the Origin of Elongation Factor P

作者：Starosta Agata L; Lassak Juergen; Peil Lauri; Atkinson Gemma C; Woolstenhulme Christopher J; Virumae Kai; Buskirk Allen; Tenson Tanel; Remme Jaanus; Jung Kirsten; Wilson Daniel N^*

来源：Cell Reports, 2014, 9(2): 476-483.

DOI：10.1016/j.celrep.2014.09.008

Bacterial ribosomes stall on polyproline stretches and require the elongation factor P (EF-P) to relieve the arrest. Yet it remains unclear why evolution has favored the development of EF-P rather than selecting against the occurrence of polyproline stretches in proteins. We have discovered that only a single polyproline stretch is invariant across all domains of life, namely a proline triplet in ValS, the tRNA synthetase, that charges tRNA(Val) with valine. Here, we show that expression of ValS in vivo and in vitro requires EF-P and demonstrate that the proline triplet located in the active site of ValS is important for efficient charging of tRNA(Val) with valine and preventing formation of mischarged Thr-tRNA(Val) as well as efficient growth of E. coli in vivo. We suggest that the critical role of the proline triplet for ValS activity may explain why bacterial cells coevolved the EF-P rescue system.

• 出版日期2014-10-23