Specific defects in double-stranded DNA unwinding and homologous pairing of a mutant RecA protein.
The DNA molecules bound to RecA filaments are extended 1.5-fold relative to B-form DNA. This extended DNA structure may be important in the recognition of homology between single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). In this study, we show that the K286N mutation specifically impaired the dsDNA unwinding and homologous pairing activities of RecA, without an apparent effect on dsDNA binding itself. In contrast, the R243Q mutation caused defective dsDNA unwinding, due to the defective dsDNA binding of the C-terminal domain of RecA. These results provide new evidence that dsDNA unwinding is essential to homology recognition between ssDNA and dsDNA during homologous pairing.
Kurumizaka
H
H
Cellular and Molecular Biology Laboratory, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan. kurumi@jota.riken.go.jp
Aihara
H
H
Ikawa
S
S
Shibata
T
T
D019943:Amino Acid Substitution / Q000235:genetics; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004278:DNA, Superhelical / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli; D009154:Mutation / Q000235:genetics*; D009690:Nucleic Acid Conformation; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011938:Rec A Recombinases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017384:Sequence Deletion / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
D004277:DNA, Single-Stranded; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D010446:Peptide Fragments; D004247:DNA; D011938:Rec A Recombinases