Initiation factors of protein biosynthesis in bacteria and their structural relationship to elongation and termination factors.
Initiation of protein biosynthesis in bacteria requires three initiation factors: initiation factor 1, initiation factor 2 and initiation factor 3. The mechanism by which initiation factors form the 70S initiation complex with initiator fMet-tRNA(fMet) interacting with the initiation codon in the ribosomal P site and the second mRNA codon exposed in the A site is not yet understood. Here, we present a model for the function of initiation factors 1 and 2 that is based on the analysis of sequence homologies, biochemical evidence and the present knowledge of the three-dimensional structures of translation factors and ribosomes. The model predicts that initiation factors 1 and 2 interact with the ribosomal A site mimicking the structure of the elongation factor G. We present data that extend the mimicry hypothesis to initiation factors 1 and 2, originally postulated for the aminoacyl-tRNA x elongation factor Tu x GTP ternary complex, elongation factor G and release factors.
Brock
S
S
Laboratorium für Biochemie, Universität Bayreuth, Germany.
Szkaradkiewicz
K
K
Sprinzl
M
M
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000737:chemistry* / Q000378:metabolism; D015977:Eukaryotic Initiation Factor-1 / Q000737:chemistry / Q000378:metabolism; D018716:Molecular Mimicry; D008969:Molecular Sequence Data; D020653:Peptide Elongation Factor G; D010444:Peptide Elongation Factor Tu / Q000737:chemistry / Q000378:metabolism; D010445:Peptide Elongation Factors / Q000737:chemistry / Q000378:metabolism*; D010448:Peptide Initiation Factors / Q000737:chemistry / Q000378:metabolism; D010454:Peptide Termination Factors / Q000378:metabolism*; D039861:Prokaryotic Initiation Factor-1; D039881:Prokaryotic Initiation Factor-2; D039665:Prokaryotic Initiation Factor-3; D014176:Protein Biosynthesis; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D015977:Eukaryotic Initiation Factor-1; D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors; D010448:Peptide Initiation Factors; D010454:Peptide Termination Factors; D039861:Prokaryotic Initiation Factor-1; D039881:Prokaryotic Initiation Factor-2; D039665:Prokaryotic Initiation Factor-3; D010444:Peptide Elongation Factor Tu