@article {2019|2063, title = {Residues in the fingers domain of the translesion DNA polymerase DinB enable its unique participation in error-prone double-strand break repair}, journal = {J Biol Chem}, volume = {294}, year = {2019}, month = {May}, pages = {7588-7600}, abstract = {

The evolutionarily conserved Escherichia coli translesion DNA polymerase IV (DinB) is one of three enzymes that can bypass potentially deadly DNA lesions on the template strand during DNA replication. Remarkably, however, DinB is the only known translesion DNA polymerase active in RecA-mediated strand exchange during error-prone double-strand break repair. In this process, a single-stranded DNA (ssDNA)-RecA nucleoprotein filament invades homologous dsDNA, pairing the ssDNA with the complementary strand in the dsDNA. When exchange reaches the 3\&$\#$39; end of the ssDNA, a DNA polymerase can add nucleotides onto the end, using one strand of dsDNA as a template and displacing the other. It is unknown what makes DinB uniquely capable of participating in this reaction. To explore this topic, we performed molecular modeling of DinB\&$\#$39;s interactions with the RecA filament during strand exchange, identifying key contacts made with residues in the DinB fingers domain. These residues are highly conserved in DinB, but not in other translesion DNA polymerases. Using a novel FRET-based assay, we found that DinB variants with mutations in these conserved residues are less effective at stabilizing RecA-mediated strand exchange than native DinB. Furthermore, these variants are specifically deficient in strand displacement in the absence of RecA filament. We propose that the amino acid patch of highly conserved residues in DinB-like proteins provides a mechanistic explanation for DinB\&$\#$39;s function in strand exchange and improves our understanding of recombination by providing evidence that RecA plays a role in facilitating DinB\&$\#$39;s activity during strand exchange.

}, keywords = {DinB, DNA damage, DNA polymerase, DNA polymerase IV, DNA repair, DNA synthesis, homologous recombination, RecA}, doi = {10.1074/jbc.RA118.006233}, author = {Tashjian, Tommy F and Danilowicz, Claudia and Molza, Anne-Elizabeth and Nguyen, Brian H and Chantal Pr{\'e}vost and Prentiss, Mara and Godoy, Veronica G} } @article {2018, title = {RecA requires two molecules of Mg2+ ions for its optimal strand exchange activity in vitro}, journal = {Nucleic Acids Res}, volume = {ahead of print}, year = {2018}, month = {Jan}, abstract = {

Mg2+ ion stimulates the DNA strand exchange reaction catalyzed by RecA, a key step in homologous recombination. To elucidate the molecular mechanisms underlying the role of Mg2+ and the strand exchange reaction itself, we investigated the interaction of RecA with Mg2+ and sought to determine which step of the reaction is affected. Thermal stability, intrinsic fluorescence, and native mass spectrometric analyses of RecA revealed that RecA binds at least two Mg2+ ions with KD \‚{\^a}{\`a} 2 mM and 5 mM. Deletion of the C-terminal acidic tail of RecA made its thermal stability and fluorescence characteristics insensitive to Mg2+ and similar to those of full-length RecA in the presence of saturating Mg2+. These observations, together with the results of a molecular dynamics simulation, support the idea that the acidic tail hampers the strand exchange reaction by interacting with other parts of RecA, and that binding of Mg2+ to the tail prevents these interactions and releases RecA from inhibition. We observed that binding of the first Mg2+ stimulated joint molecule formation, whereas binding of the second stimulated progression of the reaction. Thus, RecA is actively involved in the strand exchange step as well as bringing the two DNAs close to each other.

}, doi = {10.1093/nar/gky048}, author = {Kim, Raeyeong and Kanamaru, Shuji and Mikawa, Tsutomu and Chantal Pr{\'e}vost and Ishii, Kentaro and Ito, Kentaro and Uchiyama, Susumu and Oda, Masayuki and Iwasaki, Hiroshi and Kim, Seog K and Takahashi, Masayuki} } @inbook {2008|1565, title = {Recombination and Meiosis : Models, Means and Evolution Coll. Genome Dynamics \& Stability}, booktitle = {Genome Dynamics \& Stability}, volume = {3}, year = {2008}, pages = {65{\textendash}84}, publisher = {Springer Verlag Berlin Heidleberg}, organization = {Springer Verlag Berlin Heidleberg}, chapter = {Searching for Homology by Filaments of RecA-like Proteins}, author = {Chantal Pr{\'e}vost}, editor = {Richard Egel and Dirk-Henner Lankenau} } @inbook {2007|1563, title = {Recent Research Adv. in Structural BioInformatics}, year = {2007}, pages = {249{\textendash}274}, publisher = {Research signpost, Trivandrum, India}, organization = {Research signpost, Trivandrum, India}, chapter = {Flexible macromolecular docking: An overview of recent progress}, author = {K. Bastard and Chantal Pr{\'e}vost}, editor = {A.G. de Brevern} } @article {1995, title = {Radiation-induced damages in single- and double-stranded DNA}, journal = {Int. J. Radiat. Biol.}, volume = {67}, year = {1995}, month = {feb}, pages = {169{\textendash}76}, abstract = {

In the present study, we searched for possible effects of DNA strandedness (single and double), on two types of damages, frank strand breaks (FSB, observed at neutral pH) and alkali labile sites (ALS, leading to breaks at alkaline pH) induced by irradiation with gamma-rays (60Co) or fast neutrons (p34,Be). Sequencing gel electrophoresis allowed us to follow the occurrence of these damages at each nucleotide site in single (ss-ss), double (ds-ds), and half single-half double (ss-ds and ds-ss) stranded oligonucleotides. Globally, in DNA with random sequences of bases, no differences in FSB and ALS yield between the single and the double-stranded conformations were observed. One observes, however, an increased alkaline lability at some guanine sites belonging to single-stranded region of ss-ds or ds-ss. Nevertheless, strandedness influences the radiosensitivity of some particular sequences, i.e. the 5\&$\#$39;-AATT sequences. This region is less radiosensitive than the rest of DNA in the double helical, but not in the single-stranded conformation. The results are discussed in terms of DNA conformation.

}, author = {Isabelle, V and Chantal Pr{\'e}vost and Spotheim-Maurizot, M and Sabattier, R and Charlier, M} }