title: Real-time assembly landscape of bacterial 30S translation initiation complex.
abstract: Initiation factors guide the ribosome in the selection of mRNA and translational reading frame. We determined the kinetically favored assembly pathway of the 30S preinitiation complex (30S PIC), an early intermediate in 30S initiation complex formation in Escherichia coli. IF3 and IF2 are the first factors to arrive, forming an unstable 30S-IF2-IF3 complex. Subsequently, IF1 joins and locks the factors in a kinetically stable 30S PIC to which fMet-tRNA(fMet) is recruited. Binding of mRNA is independent of initiation factors and can take place at any time during 30S PIC assembly, depending on the cellular concentration of the mRNA and the structural determinants at the ribosome-binding site. The kinetic analysis shows both specific and cumulative effects of initiation factors as well as kinetic checkpoints of mRNA selection at the entry into translation.
authors.affiliation: Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
authors.forename: Pohl
authors.initials: P
authors.lastname: Milón
authors.forename: Cristina
authors.initials: C
authors.lastname: Maracci
authors.forename: Liudmila
authors.initials: L
authors.lastname: Filonava
authors.forename: Claudio O
authors.initials: CO
authors.lastname: Gualerzi
authors.forename: Marina V
authors.initials: MV
authors.lastname: Rodnina
mesh_terms: D001483:Base Sequence; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D039881:Prokaryotic Initiation Factor-2 / Q000737:chemistry / Q000378:metabolism*; D039665:Prokaryotic Initiation Factor-3 / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D011487:Protein Conformation; D012329:RNA, Bacterial / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D012358:RNA, Transfer, Met / Q000378:metabolism; D054680:Ribosome Subunits, Small, Bacterial / Q000737:chemistry / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D039881:Prokaryotic Initiation Factor-2; D039665:Prokaryotic Initiation Factor-3; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012358:RNA, Transfer, Met; C089238:fMet-tRNA(fMet)