Role of the two highly conserved features of initiator tRNAs in initiation of protein synthesis in eubacteria
Regulation of translation represents a crucial step in gene expression. In this mini-review, we provide brief outline of protein synthesis in bacteria, and discuss the participation of a special tRNA, the initiator tRNA (i-tRNA), in the various stages of the initiation step. The conserved features of the bacterial i-tRNA are located in its acceptor and the anticodon stems. A Watson-Crick mismatch pair (1x72) at the top of the acceptor stem along with the 2:71 and 3:70 pairs, is important in formylation of the amino acid attached to the i-tRNA. The property of formylation, facilitates i-tRNA binding to the 30S ribosome. The second feature of the presence of the three consecutive G:C pairs (29:41; 30:40 and 31:39 positions) in the anticodon stem, highly conserved in i-tRNAs from all domains of life, plays a crucial role in the transition of the i-tRNA through the various stages of formation of 70S elongation competent complex from the 30S pre-initiation complex.