9357322 Baker The bacterial virus Mu i a member of a diverse group of genetic elements that promote insertion of their own DNA into the genome of a host cell by a specialized type of genetic recombination known as DNA transposition. Many elements, including retroviruses, utilize this mechanism of integration, allowing them to insert at nearly random sites in the host DNA. The long term goal of this project is to understand the molecular mechanism of transposition. The extraordinary efficiency of Mu transposition, and the nonpathogenic nature of the virus, make Mu an ideal system for mechanistic studies. Recently, it has become clear that the active form of the Mu transposase is a tetramer of the protein bound to the paired ends of the element DNA. Current knowledge of the chemical mechanism of transposition based on work principally from the Mu and HIV systems make it very attractive to consider that the protein is activated by tetramer assembly and that the active center of the protein may lie at constructed tetramer interface. The experiments proposed here will locate and dissect the regions of the transposase involved in catalysis and in tetramer contacts. The roles of individual monomers within the active tetramer will also be investigated. %%% Transposition is the recombination reaction by which a genetic element is moved from one DNA to another. Studying this important process will lead to better understanding of HIV DNA integration, as well as other complex DNA-protein interactions such as replication, transcription and RNA processing. ***
