The long-term objective is to understand how a cell maintains the integrity of its genetic information, more particularly how it protects the DNA from damaging agents. The source of damage that will be primarily studied will be UV irradiation. The prokaryotic E. coli with its bacteriophages and the eukaryotic alga Chlorella with its chlorellophages are the organisms that will be studied because they present great technical advantages. The RecA protein of E. coli, which is both a recombinase and a so-called protease, plays a key multifaceted role in repair of damaged DNA. An understanding of all aspects of this role is one of the main goals of the research program. An activated form of the RecA protein takes part in both repair and mutagenesis of DNA. A class of mutations called recA(Prtc) confer protease activity constitutively and provide a tool for understanding how the RecA protein functions in both repair and mutagenesis. The recA(Prtc) mutants will be used to understand the nature of the mutagenic process that accompanies SOS repair as well as the spontaneous mutation process. The process of preferential mutation in physical proximity to the recA gene itself will be analyzed. These mutants also stimulate excision and transposition of the Tn5 transposon and potential mechanisms for this stimulation will be explored. The studies will be extended in an analogous way to a eukaryotic cell using a mutational approach. At least three mechanisms of repair are known that will be examined: photoreactivation, multiplicity reactivation (a recombinational mechanism), and an unknown mechanism defined by mutation that is possibly excision repair. Some of the tools developed in this work will be applied to a study of the photoinactivation of DNA in the presence of certain potential DNA binding compound such as urocanic acid present on human skin or potential photochemotherapeutic compounds like cis-bis(phenanthroline) rhodium chloride, an analog of """"""""cis-platinum"""""""".

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM035850-08
Application #
3289163
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1986-01-01
Project End
1994-06-30
Budget Start
1992-07-01
Budget End
1994-06-30
Support Year
8
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Purdue University
Department
Type
Schools of Arts and Sciences
DUNS #
072051394
City
West Lafayette
State
IN
Country
United States
Zip Code
47907
Tessman, I; Kennedy, M A; Liu, S K (1994) Unusual kinetics of uracil formation in single and double-stranded DNA by deamination of cytosine in cyclobutane pyrimidine dimers. J Mol Biol 235:807-12
Mohammad, T; Tessman, I; Morrison, H et al. (1994) Photosensitized inactivation of infectious DNA by urocanic acid, indoleacrylic acid and rhodium complexes. Photochem Photobiol 59:189-96
Tessman, I; Kennedy, M A (1994) DNA polymerase II of Escherichia coli in the bypass of abasic sites in vivo. Genetics 136:439-48
Liu, S K; Eisen, J A; Hanawalt, P C et al. (1993) recA mutations that reduce the constitutive coprotease activity of the RecA1202(Prtc) protein: possible involvement of interfilament association in proteolytic and recombination activities. J Bacteriol 175:6518-29
Kuan, C T; Tessman, I (1992) Further evidence that transposition of Tn5 in Escherichia coli is strongly enhanced by constitutively activated RecA proteins. J Bacteriol 174:6872-7
Tessman, I; Liu, S K; Kennedy, M A (1992) Mechanism of SOS mutagenesis of UV-irradiated DNA: mostly error-free processing of deaminated cytosine. Proc Natl Acad Sci U S A 89:1159-63
Kuan, C T; Tessman, I (1991) LexA protein of Escherichia coli represses expression of the Tn5 transposase gene. J Bacteriol 173:6406-10
Tessman, I; Kennedy, M A (1991) The two-step model of UV mutagenesis reassessed: deamination of cytosine in cyclobutane dimers as the likely source of the mutations associated with photoreactivation. Mol Gen Genet 227:144-8
Kuan, C T; Liu, S K; Tessman, I (1991) Excision and transposition of Tn5 as an SOS activity in Escherichia coli. Genetics 128:45-57
Liu, S K; Tessman, I (1990) Error-prone SOS repair can be error-free. J Mol Biol 216:803-7

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