Toxic mutations in the recA gene of E. coli prevent proper chromosome segregation.
The recA gene of Escherichia coli is the prototype of the recA/RAD51/DMC1/uvsX gene family of strand transferases involved in genetic recombination. In order to find mutations in the recA gene important in catalytic turnover, a genetic screen was conducted for dominant lethal mutants. Eight single amino acid substitution mutants were found to prevent proper chromosome segregation and to kill cells in the presence or absence of an inducible SOS system. All mutants catalyzed some level of recombination and constitutively stimulated LexA cleavage. The mutations occur at the monomer-monomer interface of the RecA polymer or at residues important in ATP hydrolysis, implicating these residues in catalytic turnover. Based on an analysis of the E96D mutant, a model is presented in which slow RecA-DNA dissociation prevents chromosome segregation, engendering lexA-independent, lethal filamentation of cells.
Campbell
M J
MJ
Department of Biochemistry Beckman Center, Stanford Medical Center, 279 Campus Drive, Palo Alto, CA, 94304-5307, USA. campbell@mag.com
Davis
R W
RW
D000255:Adenosine Triphosphate / Q000378:metabolism; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000378:metabolism; D002384:Catalysis; D020090:Chromosome Segregation / Q000235:genetics / Q000502:physiology*; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics*; D005798:Genes, Bacterial; D005804:Genes, Lethal; D008958:Models, Molecular; D017354:Point Mutation; D011487:Protein Conformation; D011938:Rec A Recombinases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011995:Recombination, Genetic / Q000502:physiology*; D013014:SOS Response, Genetics / Q000235:genetics / Q000502:physiology; D012697:Serine Endopeptidases / Q000378:metabolism; D015398:Signal Transduction; D000099160:LexA Repressor Protein