Molecular Dissection of Tn7's Targeting of DNA Metabolism

Cornell Univ - State: Awds Made Prior May 2010, Ithaca NY

Investigators

Abstract

This project dissects how the bacterial transposon Tn7 recognizes targets associated with DNA replication and recombination. Transposons are discrete DNA elements that are able to move within the genome of an organism. Transposons are important in the evolution of bacteria and are often responsible for allowing their host organism to live in new environments through resistance to antibiotics and metals or by novel degradation pathways. The transposon Tn7 is of special interest because of its highly evolved ability to select insertion sites associated with active DNA replication. Tn7 uses the element-encoded protein TnsE to preferentially target transposition into plasmids capable of moving between cells by recognizing factors associated with DNA replication. The ability of Tn7 to recognize mobile plasmids as insertion targets likely aids in the dispersal of the element to other bacteria. Tn7 transposition also recognizes structures associated with the repair of DNA double-strand breaks and allows Tn7 to preferentially direct transposition where DNA replication terminates. Work in this project will focus on understanding the various biochemical activities of TnsE and where these activities reside in the protein. In the project, previously identified mutations with increased transposition activity as well as newly isolated TnsE mutations will be dissected. Additional work will determine the molecular process that accounts for the distribution of TnsE-mediated transposition events around induced DNA double-strand breaks. A clear understanding of how Tn7 recognizes certain targets will lead to a better understanding of the role of transposons in evolution and the processes of DNA replication and repair in all living organisms. The utilization of undergraduates is an important component of this research project.