The long term goal of this research program is to uncover and understand mutational pathways, the DNA repair processes or avoidance mechanisms that counteract these pathways and the consequences of defects in these systems. Our basic approach has often involved characterizing """"""""mutator strains"""""""" that have higher mutation rates than wild-type, and then determining the affected pathway or repair system. We have developed new approaches for the detection of mutators, and this has allowed us to define several new mutational pathways, including one that results from the overexpression of the EmrR repressor of a multi-drug resistance efflux pump. Overexpressing a common repressor is one way to detect mutational pathways that back each other up and thus require two knockouts to produce a mutator phenotype. We hypothesize that this system acts to pump out mutagenic products of metabolism and represents the cell's first line of defense against mutagenesis. This proposal seeks to test this idea by further charactering this novel system, and also to characterize other new mutational pathways we have discovered. For instance, the use of metagenomic libraries has revealed that multiple copies of extensively repeated sequences results in global genomic instability. This will be further investigated. We will also utilize the recently completed E. coli knockout collection, consisting of close to 4,000 strains, each carrying an in-frame deletion of one of the orfs in the E. coli genome, together with our own tools to screen for new mutational pathways. We will use gene fusions to study the regulation of different repair genes and to characterize the action of new mutators, and will use several pathogen or extremophile genomes (Bordetella pertussis, Campylobacterjejeuni, and Deinococcus radiodurans) as a source for genes that might provoke mutator phenotypes in E. coli, and also that would complement different E. coli repair defects. We will also construct a system for studying mutagenesis in a pathogen such as B. pertussis. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES010875-24
Application #
7456378
Study Section
Prokaryotic Cell and Molecular Biology Study Section (PCMB)
Program Officer
Shaughnessy, Daniel
Project Start
1983-07-01
Project End
2011-06-30
Budget Start
2008-07-23
Budget End
2009-06-30
Support Year
24
Fiscal Year
2008
Total Cost
$454,599
Indirect Cost
Name
University of California Los Angeles
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Pillon, Monica C; Miller, Jeffrey H; Guarné, Alba (2011) The endonuclease domain of MutL interacts with the ? sliding clamp. DNA Repair (Amst) 10:87-93
Yang, Hanjing; Sikavi, Cameron; Tran, Katherine et al. (2011) Papillation in Bacillus anthracis colonies: a tool for finding new mutators. Mol Microbiol 79:1276-93
Becket, Elinne; Chen, Frank; Tamae, Cindy et al. (2010) Determination of hypersensitivity to genotoxic agents among Escherichia coli single gene knockout mutants. DNA Repair (Amst) 9:949-57
Xie, Yali; Yang, Hanjing; Miller, Jeffrey H et al. (2008) Cells deficient in oxidative DNA damage repair genes Myh and Ogg1 are sensitive to oxidants with increased G2/M arrest and multinucleation. Carcinogenesis 29:722-8
Yang, Hanjing; Miller, Jeffrey H (2008) Deletion of dnaN1 generates a mutator phenotype in Bacillus anthracis. DNA Repair (Amst) 7:507-14
Zeibell, Krystle; Aguila, Sharon; Yan Shi, Vivian et al. (2007) Mutagenesis and repair in Bacillus anthracis: the effect of mutators. J Bacteriol 189:2331-8