Premium
Targeting and function of proteins mediating translation initiation in organelles of P lasmodium falciparum
Author(s) -
Haider Afreen,
Allen Stacey M.,
Jackson Katherine E.,
Ralph Stuart A.,
Habib Saman
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12972
Subject(s) - apicoplast , biology , ribosome , translation (biology) , plastid , microbiology and biotechnology , organelle , protein biosynthesis , eukaryotic translation , mitochondrion , ribosomal protein , transcription (linguistics) , eukaryotic initiation factor , rna , genetics , messenger rna , gene , chloroplast , linguistics , philosophy
Summary The malaria parasite P lasmodium falciparum has two translationally active organelles – the apicoplast and mitochondrion, which import nuclear‐encoded translation factors to mediate protein synthesis. Initiation of translation is a complex step wherein initiation factors ( IF s) act in a regulated manner to form an initiation complex. We identified putative organellar IF s and investigated the targeting, structure and function of IF 1, IF 2 and IF 3 homologues encoded by the parasite nuclear genome. A single Pf IF 1 is targeted to the apicoplast. Apart from its critical ribosomal interactions, Pf IF 1 also exhibited nucleic‐acid binding and melting activities and mediated transcription anti‐termination. This suggests a prominent ancillary function for Pf IF 1 in destabilisation of DNA and RNA hairpin loops encountered during transcription and translation of the A + T rich apicoplast genome. Of the three putative IF 2 homologues, only one ( Pf IF 2a) was an organellar protein with mitochondrial localisation. We additionally identified an IF 3 ( Pf IF 3a) that localised exclusively to the mitochondrion and another protein, Pf IF 3b, that was apicoplast targeted. Pf IF 3a exhibited ribosome anti‐association activity, and monosome splitting by Pf IF 3a was enhanced by ribosome recycling factor ( Pf RRF2) and Pf EF‐ G M it . These results fill a gap in our understanding of organellar translation in P lasmodium , which is the site of action of several anti‐malarial compounds.