Abstract
The product of the cloned recA+ gene of Proteus mirabilis substitutes for a defective recA protein in Escherichia coli recA- mutants and restores recombination, repair, and prophage induction functions to near normal levels (Eitner, G., Adler, B., Lanzov, V. A., and Hofemeister, J. (1982) Mol. Gen. Genet. 185, 481-486). In this paper, we report the purification to near homogeneity of the P. mirabilis recA protein (recApm). The polypeptide has a molecular weight similar to that of E. coli recA protein (recAec) and shows partial identity with recAec when reacted against antibodies specific for the E. coli recA protein. recApm catalyzes the hydrolysis of ATP in the presence of single-stranded but not double-stranded DNA. We have compared the recombination-like activities of recApm with those of recAec and found them to be similar. In the presence of ATP and Mg2+, stoichiometric amounts of recApm promote the complete reciprocal exchange of strands between gapped circular and linear duplex DNA molecules. The enzyme also efficiently promotes the formation of D-loops from circular duplex DNA and homologous single-stranded fragments. However, although recApm and recAec share the above physical and functional similarities, they differ in their ability to interact with the E. coli single strand binding protein to catalyze the transfer of one DNA strand from a linear duplex to a single-stranded circle.
Highlights
The product of the cloned mcA+ gene of Proteus mi- (Fig. I C ) or nicked duplex DNA molecules [9,10,11,12]
The recipmbilis substitutes for adefective recA proteinin Esch- rocal exchange reaction is of particular interest since it resemerichia coli recA- mutants andrestores recombination, bles a specific biochemical reaction thought to occur during repair, and prophage induction functionsto near nor- postreplication repair of damaged DNA [10, 11]
Mutants in the recA gene of P. mirabilis this paper, we report the purificationto near homogeneity of the P. mimbilis recA protein
Summary
COMPARISON WITH ESCHERICHIA COLI recA PROTEIN; SPECIFICITY OF INTERACTION WITH SINGLE STRAND BINDING PROTEIN*. From the Dewartments of Molecular Biowhvsics a n d Biochemistry, a n d Therapeutic Radiology, Yale University, New ”. The product of the cloned mcA+ gene of Proteus mi- (Fig. I C ) or nicked duplex DNA molecules [9,10,11,12]. The recipmbilis substitutes for adefective recA proteinin Esch- rocal exchange reaction is of particular interest since it resemerichia coli recA- mutants andrestores recombination, bles a specific biochemical reaction thought to occur during repair, and prophage induction functionsto near nor- postreplication repair of damaged DNA [10, 11]
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