Saccharomyces cerevisiae Dmc1 and Rad51 Proteins Preferentially Function with Tid1 and Rad54 Proteins, Respectively, to Promote DNA Strand Invasion during Genetic Recombination

Amitabh V Nimonkar,Christopher C Dombrowski,Joseph S Siino,Alicja Z Stasiak,Andrzej Stasiak,Stephen C Kowalczykowski

doi:10.1074/jbc.m112.373290

Amitabh V Nimonkar, Christopher C Dombrowski + Show 4 more

Open Access

https://doi.org/10.1074/jbc.m112.373290

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Abstract

The Saccharomyces cerevisiae Dmc1 and Tid1 proteins are required for the pairing of homologous chromosomes during meiotic recombination. This pairing is the precursor to the formation of crossovers between homologs, an event that is necessary for the accurate segregation of chromosomes. Failure to form crossovers can have serious consequences and may lead to chromosomal imbalance. Dmc1, a meiosis-specific paralog of Rad51, mediates the pairing of homologous chromosomes. Tid1, a Rad54 paralog, although not meiosis-specific, interacts with Dmc1 and promotes crossover formation between homologs. In this study, we show that purified Dmc1 and Tid1 interact physically and functionally. Dmc1 forms stable nucleoprotein filaments that can mediate DNA strand invasion. Tid1 stimulates Dmc1-mediated formation of joint molecules. Under conditions optimal for Dmc1 reactions, Rad51 is specifically stimulated by Rad54, establishing that Dmc1-Tid1 and Rad51-Rad54 function as specific pairs. Physical interaction studies show that specificity in function is not dictated by direct interactions between the proteins. Our data are consistent with the hypothesis that Rad51-Rad54 function together to promote intersister DNA strand exchange, whereas Dmc1-Tid1 tilt the bias toward interhomolog DNA strand exchange.

Highlights

DNA strand exchange proteins Dmc1 and Rad51 and translocases Tid1 and Rad54 function in DNA break repair during meiosis
We demonstrated previously that N-terminal glutathione S-transferase (GST)-tagged Tid1 actively translocates on double-stranded DNA (dsDNA) in an ATPdependent manner [32]
We examined the kinetic parameters for ATP hydrolysis (Fig. 1D) and determined that Tid1 is a dsDNA-dependent ATPase with Km for ATP and Vmax values of 172 Ϯ 21 ␮M and 24.2 Ϯ 0.4 ␮M/min, respectively

Summary

Background

DNA strand exchange proteins Dmc and Rad and translocases Tid and Rad function in DNA break repair during meiosis. During meiosis I, the homologous chromosomes form a tripartite proteinaceous structure termed the synaptonemal complex and undergo crossover recombination at frequencies 100 –1000-fold higher than in vegetative cells [1]. A number of proteins that are classified as “mediators” act as catalysts to replace replication protein A with the DNA strand exchange proteins, Rad, or its meiosis-specific homolog, Dmc, to form nucleoprotein filaments [11]. These filaments represent the active species that search and pair with an intact template, the sister chromatid or. Our data provide biochemical evidence for the hypothesis [22] that Dmc and Tid interact to promote homologous pairing during meiotic recombination

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DISCUSSION