Less Is More: Neisseria gonorrhoeae RecX Protein Stimulates Recombination by Inhibiting RecA |
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| Authors: | Marielle C. Gruenig Elizabeth A. Stohl Sindhu Chitteni-Pattu H. Steven Seifert Michael M. Cox |
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| Affiliation: | From the ‡Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706 and ;the §Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611 |
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| Abstract: | Escherichia coli RecX (RecXEc) is a negative regulator of RecA activities both in the bacterial cell and in vitro. In contrast, the Neisseria gonorrhoeae RecX protein (RecXNg) enhances all RecA-related processes in N. gonorrhoeae. Surprisingly, the RecXNg protein is not a RecA protein activator in vitro. Instead, RecXNg is a much more potent inhibitor of all RecANg and RecAEc activities than is the E. coli RecX ortholog. A series of RecXNg mutant proteins representing a gradient of functional deficiencies provide a direct correlation between RecANg inhibition in vitro and the enhancement of RecANg function in N. gonorrhoeae. Unlike RecXEc, RecXNg does not simply cap the growing ends of RecA filaments, but it directly facilitates a more rapid RecA filament disassembly. Thus, in N. gonorrhoeae, recombinational processes are facilitated by RecXNg protein-mediated limitations on RecANg filament presence and/or length to achieve maximal function. |
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| Keywords: | DNA DNA Enzymes DNA Recombination DNA Repair Nucleic Acid Enzymology Escherichia coli Neisseria gonorrhoeae RecA RecX |
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