[Interaction with DNA and aggregation properties of C-terminal fragment of RecA protein]

C-terminal fragment of Escherichia coli RecA protein 150 amino acids residues in length--the product of RecA protein BrCN-hydrolysis--was isolated by single stranded DNA-cellulose chromatography. In low salt buffer this fragment tightly bounds with single and double stranded DNAs. Aggregational properties of the fragment are similar to such of native protein: the fragment oligomerises in low salt buffer and precipitates in the presence of Mg2+. Double stranded DNA in the last case coprecipitates with the fragment, forming a complex which is stable at higher salt concentration, like the complexes with a native RecA protein. These results indicate that the C-terminal half of RecA protein participates in DNA binding and intersubunits interaction of RecA protein.