Recombinase A: Difference between revisions

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Alexander Berchansky, Michal Harel, Jaime Prilusky, Taylor Light, Joel L. Sussman

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 == RecA and Hofmeister Salts ==
-High salt concentrations have also been shown to be able to elongate the RecA protein filament as well. Petukhov et al. demonstrated that a high concentration of NaCl increased the helical pitch from 7.8 to 8.6 nm.<ref name=Peukhov> Peukhov, M.; Lebedev, D.; Shalguev, V.; Islamov, A.; Kruklin, A.; Lanzov, V.; Isaev-Ivanov, V. Conformational Flexibility of RecA Protein Filament: Transitions between Compressed and Stretched States. Proteins: Struct.,Funct., Bioinf. 2006,65, 296-304. DOI: 10.1002/prot.21116 </ref> Thus, high salt concentrations appear to induce the active (stretched) form of RecA in the absence of DNA.<ref name=Peukhov> Peukhov, M.; Lebedev, D.; Shalguev, V.; Islamov, A.; Kruklin, A.; Lanzov, V.; Isaev-Ivanov, V. Conformational Flexibility of RecA Protein Filament: Transitions between Compressed and Stretched States. Proteins: Struct.,Funct., Bioinf. 2006,65, 296-304. DOI: 10.1002/prot.21116 </ref>  Other studies have found that the free Magnesium ion binds to RecA (see <scene name='41/413118/Reca_adp_mg/3'>binding sites</scene>) and extends the filament more than 150% compared to the filament when DNA is bound.<ref name=Lusetti>  Lusetti, S. L.; Shaw, J. J.; Cox, M. M. Magnesium Ion-dependent Activation of the RecA Protein
+High salt concentrations have also been shown to be able to elongate the RecA protein filament as well. Petukhov et al. demonstrated that a high concentration of NaCl increased the helical pitch from 7.8 to 8.6 nm.<ref name=Peukhov> Peukhov, M.; Lebedev, D.; Shalguev, V.; Islamov, A.; Kruklin, A.; Lanzov, V.; Isaev-Ivanov, V. Conformational Flexibility of RecA Protein Filament: Transitions between Compressed and Stretched States. Proteins: Struct.,Funct., Bioinf. 2006,65, 296-304. DOI: 10.1002/prot.21116 </ref> Thus, high salt concentrations appear to induce the active (stretched) form of RecA in the absence of DNA.<ref name=Peukhov> Peukhov, M.; Lebedev, D.; Shalguev, V.; Islamov, A.; Kruklin, A.; Lanzov, V.; Isaev-Ivanov, V. Conformational Flexibility of RecA Protein Filament: Transitions between Compressed and Stretched States. Proteins: Struct.,Funct., Bioinf. 2006,65, 296-304. DOI: 10.1002/prot.21116 </ref>  Other studies have found that the free Magnesium ion binds to RecA (see <scene name='41/413118/Reca_adp_mg/3'>binding sites</scene>; Mg ion is colored lime green) and extends the filament more than 150% compared to the filament when DNA is bound.<ref name=Lusetti>  Lusetti, S. L.; Shaw, J. J.; Cox, M. M. Magnesium Ion-dependent Activation of the RecA Protein
 Involves the C Terminus. J. Biol. Chem. 2003, 278, 16381–16388. DOI: 10.1074/jbc.M212916200 </ref> Moreover, although normally RecA requires DNA to hydrolyze ATP, high salt concentrations are able to stimulate ATP hydrolysis in the absence of DNA.<ref name=Pugh> Pugh, B. F.;  Cox, M. M. High Salt Activation of recA Protein ATPase in the Absence of DNA. J. Biol. Chem.1988, 263, 76-83. PMID: 2826451 </ref> Brenner and Zlotnick reported that the presence of monovalent salts changed the distribution of RecA aggregation states and that the more aggregated structures corresponded to higher protein concentration.<ref name=Brenner> Brenner, S. L.; Zlotnick, A. RecA Protein Self-assembly: Multiple Discrete Aggregation States. J. Mol. Biol. 1988, 204, 959-972. DOI: 10.1016/0022-2836(88)90055-1 </ref>  Previous studies have shown that various Hofmeister salts affect the secondary structure, stability, and aggregation behavior of RecA differently.<ref name=Brenner> Brenner, S. L.; Zlotnick, A. RecA Protein Self-assembly: Multiple Discrete Aggregation States. J. Mol. Biol. 1988, 204, 959-972. DOI: 10.1016/0022-2836(88)90055-1 </ref> <ref name=Cannon> Cannon, W. R.; Talley, N. D.; Danzig, B. A.; Liu, X. L.; Martinez, J. S.; Shreve, A. P.; MacDonald, G. Ion specific influences on the stability and unfolding transitions of a naturally aggregating protein; RecA. Biophys. Chem. 2012, 163-164, 56-63. DOI: 10.1016/j.bpc.2012.02.005 </ref> Additionally, RecA has been demonstrated to follow the inverse-anionic Hofmeister series and the presence of some ions promotes nonspecific aggregation.<ref name=Cannon> Cannon, W. R.; Talley, N. D.; Danzig, B. A.; Liu, X. L.; Martinez, J. S.; Shreve, A. P.; MacDonald, G. Ion specific influences on the stability and unfolding transitions of a naturally aggregating protein; RecA. Biophys. Chem. 2012, 163-164, 56-63. DOI: 10.1016/j.bpc.2012.02.005 </ref>
 == References ==