Binding of RecA protein to single-stranded nucleic acids: spectroscopic studies using fluorescent polynucleotides.

摘要: Binding of the recA gene product from Escherichia coli to single-stranded polynucleotides has been investigated using poly(dA) that have modified by chloroacetaldehyde yield fluorescent 1,N6-ethenoadenine (epsilon A) bases. A strong enhancement quantum poly(d epsilon is induced upon RecA protein binding. 4-fold increase observed in absence ATP or gamma S and a 7-fold presence either nucleoside triphosphate. can bind both Mg2+ ions (or S) but are required observe binding at pH 7.5. RecA-poly(d complex induces dissociation polynucleotide followed re-binding [RecA-ATP-Mg2+] ternary complex. Whereas ATP-induced complexes fast process, subsequent reaction slow. model proposed whereby involves slow nucleation elongation processes along backbone. The shown involve least trimer tetramer. Polymerization stops when entirely covered with 6 +/- 1 nucleotides per monomer. hydrolysis then release RecA-ADP template.