Role of tyrosine residue 264 of RecA for the binding of cofactor and DNA.

摘要: The tyrosine fluorescence of the RecA protein is quenched by about 15% upon binding cofactor analog adenosine 5'-O-(3-thiotriphosphate) (ATPgammaS). This quenching not observed with a modified in which residue at position 264 (Tyr-264) replaced for alanine site-directed mutagenesis, modification also results decrease affinity cofactor. indicates that Tyr-264 responsible change and close to or within site. Upon DNA binding, both wild type RecA, indicating affects environment other residues than Tyr-264. However, significantly smaller protein, suggesting as well residue(s) may be affected binding. Changed properties remaining result slightly different mode are possible. an important allosteric effect induced RecA. In recent crystal structure RecA-ADP published Story Steitz (Story, R. M., Steitz, T. A. (1992) Nature 355, 374-376), ADP stacked Tyr-103 does interact fact we observe no interaction ATPgammaS (as evidenced from absence change) but instead suggest conformational difference between complexes with, respectively, ATP.