4fcy
From Proteopedia
Crystal structure of the bacteriophage Mu transpososome
Structural highlights
FunctionTNPA_BPMU Responsible for viral genome integration into the host chromosome. During integration of the incoming virus, DDE-recombinase A cleaves both viral DNA ends and the resulting 3'-OH perform a nucleophilic attack of the host DNA. The 5' flanking DNA attached to the ends of the viral genome (flaps) are resected by the DDE-recombinase A endonuclease activity, with the help of host chaperone ClpX. The gaps created in the host chromosome by the viral genome insertion are repaired by the host primary machinery for double-strand break repair. Responsible for replication of the viral genome by replicative transposition. During replicative transposition, DDE-recombinase A is part of the transpososome complex. DDE-recombinase A cleaves the viral DNA and the resulting 3'-OH performs a nucleophilic attack of the host DNA. The 5' flanking DNA is not resected and an intermediary structure is formed. This structure is resolved by target-primed replication leading to two copies of the viral genome (the original one and the copied one). Host ClpX and translation initiation factor IF2 play an essential transpososome-remodeling role by releasing the block between transposition and DNA replication. Successive rounds of replicative transposition can lead up to 100 copies of the viral genome. Promotes replication and thereby lytic development by competing with repressor c (Repc) for binding to the internal activation sequence (IAS) in the enhancer/operator region. The outcome of this competition determines if the virus enters latency or starts replication. Publication Abstract from PubMedStudies of bacteriophage Mu transposition paved the way for understanding retroviral integration and V(D)J recombination as well as many other DNA transposition reactions. Here we report the structure of the Mu transpososome--Mu transposase (MuA) in complex with bacteriophage DNA ends and target DNA--determined from data that extend anisotropically to 5.2 A, 5.2 A and 3.7 A resolution, in conjunction with previously determined structures of individual domains. The highly intertwined structure illustrates why chemical activity depends on formation of the synaptic complex, and reveals that individual domains have different roles when bound to different sites. The structure also provides explanations for the increased stability of the final product complex and for its preferential recognition by the ATP-dependent unfoldase ClpX. Although MuA and many other recombinases share a structurally conserved 'DDE' catalytic domain, comparisons among the limited set of available complex structures indicate that some conserved features, such as catalysis in trans and target DNA bending, arose through convergent evolution because they are important for function. The Mu transpososome structure sheds light on DDE recombinase evolution.,Montano SP, Pigli YZ, Rice PA Nature. 2012 Nov 15;491(7424):413-7. doi: 10.1038/nature11602. Epub 2012 Nov 7. PMID:23135398[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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