EF-P (elongation factor P) is an essential protein that in bacteria stimulates the formation of the first peptide bonds in protein synthesis.[1][2] Studies show that EF-P prevents ribosomes from stalling during the synthesis of proteins containing consecutive prolines.[1] EF-P binds to a site located between the binding site for the peptidyl tRNA (P site) and the exiting tRNA (E site). It spans both ribosomal subunits with its amino-terminal domain positioned adjacent to the aminoacyl acceptor stem and its carboxyl-terminal domain positioned next to the anticodon stem-loop of the P site-bound initiator tRNA.[3] The EF-P protein shape and size is very similar to a tRNA and interacts with the ribosome via the exit “E” site on the 30S subunit and the peptidyl-transferase center (PTC) of the 50S subunit.[4] EF-P is a translation aspect of an unknown function,[1] therefore It probably functions indirectly by altering the affinity of the ribosome for aminoacyl-tRNA, thus increasing their reactivity as acceptors for peptidyl transferase.
A C-terminal domain which adopts an OB-fold, with five beta-strands forming a beta-barrel in a Greek-key topology[5]
Eukaryotes and archaea lack EF-P. In these domains, a similar function is performed by the archaeo-eukaryotic initiation factor, a/eIF-5A, which exhibits some modest sequence and structural similarity with EF-P.[2][6] There are, however, important differences between EF-p and eIF-5A. (a) EF-P has a structure similar to that of L-shaped tRNA and it contains three (I,II and III) β-barrel domains. In contrast, eIF-5A contains only two domains (C and N) with a corresponding size difference.[2] (b) Moreover, as opposed to eIF-5A, which contains the non-proteinogenic amino acidhypusine that is essential for its activity, EF-P displays a diversity of post-transcriptional modifications at the analogous position (β-lysylation of lysine residue, rhamnosylation of arginine residue, or none at all).[7][8]
^Rossi D, Kuroshu R, Zanelli CF, Valentini SR (2013). "eIF5A and EF-P: two unique translation factors are now traveling the same road". Wiley Interdisciplinary Reviews. RNA. 5 (2): 209–22. doi:10.1002/wrna.1211. PMID24402910. S2CID25447826.