Translation factor IF2 at the interface of transposition and replication by the PriA-PriC pathway

• Published in: Molecular microbiology 2007-12, Vol.66 (6), p.1566-1578
• Main Authors: North, Stella H, Kirtland, Sandy E, Nakai, Hiroshi
• Format: Article
• Language: English
• Subjects: Bacteriology; Bacteriophage mu - genetics; Bacteriophage mu - metabolism; Biochemistry; Biological and medical sciences; Deoxyribonucleic acid; DNA; DNA Helicases - genetics; DNA Helicases - metabolism; DNA Replication; Electrophoresis, Polyacrylamide Gel; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Fundamental and applied biological sciences. Psychology; Genetics; Microbiology; Models, Biological; Molecular biology; Prokaryotic Initiation Factor-2 - genetics; Prokaryotic Initiation Factor-2 - metabolism; Protein Binding; Proteins; Tandem Mass Spectrometry
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2007.06022.x

Bacteriophage Mu DNA synthesis is initiated during transposition by replication restart proteins PriA, DnaT and either PriB or PriC. The PriA-PriC pathway requires PriA's helicase activity and other host factors that promote the orderly transition from transpososome to replisome on the Mu DNA template. The host factor MRFα-PR, which removes obstacles to PriA binding and promotes the PriA-PriC pathway, was identified to be the translation initiation factor IF2. Purified isoform IF2-2, which is truncated at the N-terminal end, had full MRFα-PR activity whereas full-length IF2-1 was inactive. IF2-2 was bound to the Mu DNA template specifically at the step for prereplisome assembly. Prior steps in the orderly transition from transpososome were essential to promote efficient IF2-2 binding. Moreover, PriA helicase activity was subsequently needed to displace IF2-2, remodelling the template to permit replisome assembly. IF2's role in the transition mechanism as well as its function as G protein and translation factor suggest its potential to regulate DNA synthesis by this pathway.