Translation factor IF2 at the interface of transposition and replication by the PriA-PriC pathway |
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Authors: | North Stella H Kirtland Sandy E Nakai Hiroshi |
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Affiliation: | Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Rm. 331 Basic Science Bldg., 3900 Reservoir Road NW, Washington, DC 20057-1455, USA. |
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Abstract: | 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 MRFalpha-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 MRFalpha-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. |
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