Biology

Dr. Hardeep Kaur
Yale university, School of Medicine, USA

Abstract:

Double strand breaks (DSBs) are most common DNA lesions that are formed in cell and can result from exogenous agents or due to errors in DNA replication. If not repaired, DSBs can lead to gross genomic rearrangements and are major challenge to maintain genome integrity. DBSs can be repaired by homologous recombination using template sequence to copy the missing information and results in the formation of crossover (CO, exchange of flanking markers) and noncrossover (NCO, no exchange of flanking markers) recombination products. COs are essential for the proper chromosome segregation during meiosis but during mitotic divisions formation of NCOs are favored over COs to avoid loss of heterogeneity and hence predisposition to cancer.  An evolutionary conserved complex of Sgs1 (Bloom Helicase)-Top3 (Topoisomerase III) -Rmi1 (STR) plays a critical role in regulating CO formation during homologous recombination.  Our results suggested an essential role of STR complex in recombination pathway choice and CO formation during meiosis and in avoiding CO formation during mitosis. We further propose that Top3 and Rmi1 also have STR complex independent functions in completing nuclear divisions.