The objective of the proposed research is to understand the chemical and conformational properties of the repressor molecules which control DNA damage-inducible functions. These functions, such as viral induction, increased mutagenesis, inhibition of cell division, etc., are also induced by the same agents that lead to carcinogenesis in animal cells. The two phenomena may share similar molecular mechanisms. In Escherichia coli, the repressor of these functions is the LexA protein. During induction there is accumulation of single-strand DNA in the cell, which is required for the activation of the RecA protease and possibly for the binding of repressors. The LexA protein, as well as the phage repressor in lysogens, undergo a proteolytic cleavage, with concomitant derepression of the genes under their control. This project attempts to study the chemical and conformational determinants of Lambda repressor concerned with the induction phenomenon by monoclonal antibody analyses. 1) We will isolate and identify specific antibodies that recognize different amino acid sequences of the COOH-terminal fragment of repressor. 2) Attempt to relate the primary sequence to the tertiary structure of the fragment. 3) Define specific residues or conformations of the repressor essential for: a) the cleavage site; b) the interaction with RecA protein; c) increased or decreased susceptibility to the protease; d) dimer formation; and e) cooperative interaction of the dimers when bound to adjacent operator sequences. Polyvalent antibodies against short synthetic peptides will also be attempted.
| Sussman, R; Alexander, H B (1989) Structural analysis of the carboxy terminus of bacteriophage lambda repressor determined by antipeptide antibodies. J Bacteriol 171:1235-44 |
