Recombination Triple Helix, R-form DNA. A Stereochemical Model for Recognition and Strand ExchangeStructural Biology: The State of the Art: proceedings of the eighth Conversation in the Discipline Biomolecular Stereodynamics, held at the State University of New York at Albany, June 22-26, 1993. (1993)
Based on the energy calculations, a model forthe recombination triplex is proposed, which is stereochemically possible for any arbitrary sequence and consistent with the chemical modification data for the RecA mediated joint molecules. The detailed mechanisms of the recognition and strand exchange are suggested, the key elements of which are the isomorphism of the triplets and the coordinated rotations of bases in the three strands.
Each base from the third strand recognizes both purine and pyrimidine from the duplex and is located in the center of the major groove. Partial charges on the third strand bases are strictly complementary to the charges of the Watson-Crick pairs. Hence, the initial selection of the homologous sequence may occur through electrostatic interactions of the third strand with the closed WC pairs rather than with the open bases. This recognition code may be applicable to both recombination and transcription.
In the collapsed triplex with a rise of about 3.4 A. the bases from the third strand can interact with two neighboring WC base pairs simultaneously, that-could lead to recognition errors. In the triplex extended up to 5.1 A in the presence of RecA protein, these mismatches are impossible. Therefore, we suggest that an extended DNA structure increases the fidelity of recognition, and RecA plays the role of a "chaperone".
LocationAlbany, New York
Citation InformationV. B. Zhurkin, G. Raghunathan, N. B. Ulyanov, R. D. Camerini-Otero, et al.. "Recombination Triple Helix, R-form DNA. A Stereochemical Model for Recognition and Strand Exchange" Structural Biology: The State of the Art: proceedings of the eighth Conversation in the Discipline Biomolecular Stereodynamics, held at the State University of New York at Albany, June 22-26, 1993. (1993)
Available at: http://works.bepress.com/robert-jernigan/27/