Contacts between mammalian mitochondrial translational initiation factor 3 and ribosomal proteins in the small subunit.
Mammalian mitochondrial translational initiation factor 3 (IF3(mt)) binds to the small subunit of the ribosome displacing the large subunit during the initiation of protein biosynthesis. About half of the proteins in mitochondrial ribosomes have homologs in bacteria while the remainder are unique to the mitochondrion. To obtain information on the ribosomal proteins located near the IF3(mt) binding site, cross-linking studies were carried out followed by identification of the cross-linked proteins by mass spectrometry. IF3(mt) cross-links to mammalian mitochondrial homologs of the bacterial ribosomal proteins S5, S9, S10, and S18-2 and to unique mitochondrial ribosomal proteins MRPS29, MRPS32, MRPS36 and PTCD3 (Pet309) which has now been identified as a small subunit ribosomal protein. IF3(mt) has extensions on both the N- and C-termini compared to the bacterial factors. Cross-linking of a truncated derivative lacking these extensions gives the same hits as the full length IF3(mt) except that no cross-links were observed to MRPS36. IF3 consists of two domains separated by a flexible linker. Cross-linking of the isolated N- and C-domains was observed to a range of ribosomal proteins particularly with the C-domain carrying the linker which showed significant cross-linking to several ribosomal proteins not found in prokaryotes.
Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290, USA.
Md Emdadul
ME
Haque
Hasan
H
Koc
Huseyin
H
Cimen
Emine C
EC
Koc
Linda L
LL
Spremulli
D000818:Animals; D002417:Cattle; D039621:Eukaryotic Initiation Factor-3 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008322:Mammals / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D008958:Models, Molecular; D010442:Peptide Chain Initiation, Translational / Q000235:genetics; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017433:Protein Structure, Secondary; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054682:Ribosome Subunits, Small, Eukaryotic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D039621:Eukaryotic Initiation Factor-3; D024101:Mitochondrial Proteins; D012269:Ribosomal Proteins