@article {2000|1431, title = {A mechanism for RecA-promoted sequence homology recognition and strand exchange between single-stranded DNA and duplex DNA, via triple-helical intermediates}, journal = {J. Biomol. Struct. Dyn.}, number = {Sp. Iss. S1}, year = {2000}, note = {11th Conversation in Biomolecular Stereodynamics, ALBANY, NEW YORK, JUN 15-19, 1999}, pages = {147{\textendash}153}, author = {Bertucat, G and Lavery, R and Chantal Pr{\'e}vost} } @article {1999|1600, title = {A molecular model for RecA-promoted strand exchange via parallel triple-stranded helices}, journal = {Biophys. J.}, volume = {77}, year = {1999}, month = {sep}, pages = {1562{\textendash}76}, abstract = {

A number of studies have concluded that strand exchange between a RecA-complexed DNA single strand and a homologous DNA duplex occurs via a single-strand invasion of the minor groove of the duplex. Using molecular modeling, we have previously demonstrated the possibility of forming a parallel triple helix in which the single strand interacts with the intact duplex in the minor groove, via novel base interactions (Bertucat et al., J. Biomol. Struct. Dynam. 16:535-546). This triplex is stabilized by the stretching and unwinding imposed by RecA. In the present study, we show that the bases within this triplex are appropriately placed to undergo strand exchange. Strand exchange is found to be exothermic and to result in a triple helix in which the new single strand occupies the major groove. This structure, which can be equated to so-called R-form DNA, can be further stabilized by compression and rewinding. We are consequently able to propose a detailed, atomic-scale model of RecA-promoted strand exchange. This model, which is supported by a variety of experimental data, suggests that the role of RecA is principally to prepare the single strand for its future interactions, to guide a minor groove attack on duplex DNA, and to stabilize the resulting, stretched triplex, which intrinsically favors strand exchange. We also discuss how this mechanism can incorporate homologous recognition.

}, doi = {10.1016/S0006-3495(99)77004-9}, author = {Bertucat, G and Richard Lavery and Chantal Pr{\'e}vost} } @article {1998|1659, title = {A model for parallel triple helix formation by RecA: single-single association with a homologous duplex via the minor groove}, journal = {J. Biomol. Struct. Dyn.}, volume = {16}, year = {1998}, month = {dec}, pages = {535{\textendash}46}, abstract = {

The nucleoproteic filaments of RecA polymerized on single stranded DNA are able to integrate double stranded DNA in a coaxial arrangement (with DNA stretched by a factor 1.5), to recognize homologous sequences in the duplex and to perform strand exchange between the single stranded and double stranded molecules. While experimental results favor the hypothesis of an invasion of the minor groove of the duplex by the single strand, parallel minor groove triple helices have never been isolated or even modeled, the minor groove offering little space for a third strand to interact. Based on an internal coordinate modeling study, we show here that such a structure is perfectly conceivable when the two interacting oligomers are stretched by a factor 1.5, in order to open the minor groove of the duplex. The model helix presents characteristics that coincide with known experimental data on unwinding, base pair inclination and inter-proton distances. Moreover, we show that extension and unwinding stabilize the triple helix. New patterns of triplet interaction via the minor groove are presented.

}, doi = {10.1080/07391102.1998.10508268}, author = {Bertucat, G and Richard Lavery and Chantal Pr{\'e}vost} }