Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Rapid Propagational Interactions of Slow Binding Inhibitor with RecA Protein Occur on the Longer Nucleoprotein Filaments: Jong-Il Kim; J. Microbiol. 2010;48(1):71-76. Published online March 11, 2010; DOI: https://doi.org/10.1007/s12275-009-0306-4

Abstract: RecA protein is a DNA-dependent ATPase. RecA protein-mediated ATP hydrolysis occurs throughout the filamentous nucleoprotein complexes of RecA and DNA. Nucleotide analog ATP[γS] may not act simply as a competitive inhibitor, leading to inhibition kinetic patterns that are informative. When a mixture of ATP and ATP[γS] is present at the beginning of reaction, a transient phase lasting several minutes is observed in which the system approaches the state characteristic of the new ATP/ATP[γS] ratio. This phase consists of a burst or lag in ATP hydrolysis, depending on whether ATP or ATP[γS] respectively, is added first. The transition phase reflects a slow conformational change in a RecA monomer or a general adjustment in the structure of RecA filaments. The RecA filaments formed on longer DNA cofactor were more sensitive, and respond more rapidly to ATP[γS] than on shorter DNA cofactors.

Analysis of Double Stranded DNA-dependent Activities of Deinococcus radiodurans RecA Protein: Jong-Il Kim; J. Microbiol. 2006;44(5):508-514.; DOI: https://doi.org/2447 [pii]

Abstract: In this study, the double-stranded DNA-dependent activities of Deinococcus radiodurans RecA protein (Dr RecA) were characterized. The interactions of the Dr RecA protein with double-stranded DNA were determined, especially dsDNA-dependent ATP hydrolysis by the Dr RecA protein and the DNA strand exchange reaction, in which multiple branch points exist on a single RecA protein-DNA complex. A nucleotide cofactor (ATP or dATP ) was required for the Dr RecA protein binding to duplex DNA. In the presence of dATP, the nucleation step in the binding process occurred more rapidly than in the presence of ATP. Salts inhibited the binding of the Dr RecA protein to double-stranded DNA. Doublestranded DNA-dependent ATPase activities showed a different sensitivity to anion species. Glutamate had only a minimal effect on the double-stranded DNA-dependent ATPase activities, up to a concentration of 0.7 M. In the competition experiment for Dr RecA protein binding, the Dr RecA protein manifested a higher affinity to double-stranded DNA than was observed for single-stranded DNA.

Physiological Relevance of Salt Environment for in vitro recA System: Kim , Jong Il; J. Microbiol. 1999;37(2):59-65.

Abstract: RecA protein can promote strand assimilation, homologous pairing, and strand exchange. All these reactions require DNA-dependent ATP hydrolysis by recA protein, and the activities of recA protein are affected by the ionic environment. In this experiment, DNA-dependent ATPase activity showed different sensitivity to anionic species. ATP hydrolysis and strand exchange were relatively sensitive to salt in the reactions with NaCl, strongly inhibited at 100 mM NaCl. However, the inhibition by sodium acetate or sodium glutamate was not observed at 50∼100 mM concentration. Addition of sodium glutamate to the standard reaction condition increased the apparent efficiency of ATP hydrolysis during strand exchange. The condition including 50∼100 mM sodium-glutamate might be similar to the physiological condition.

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