, a novel regulator functions as a repressor of L-sorbose utilization in .

Background And Objectives: Monosomy of chromosome 5 associated with utilization of non-canonical sugar L-sorbose is one of the well-studied aneuploidies in . Stress-induced ploidy changes are crucial determinants for pathogenicity and genetic diversity in The five scattered regulatory regions (A, B, C, 135, and 139) comprising of two functionally redundant pathways (SUR1 and SUR2) were found to be responsible for the growth on L-sorbose. So far, three genes such as and have been identified in region A, region 135 and region C, respectively. In this study we have verified the role of region B in this regulatory pathway.

Materials And Methods: We employed a combinatorial gene deletion approach to verify the role of region B followed by co-over expression studies and qRT-PCR to identify the regulatory role of this region.

Results: We confirmed the role of region B in the regulation of gene expression. The qRT-PCR results showed that regulation occurs at transcriptional level along with other two regions in SUR1 pathway. A previously uncharacterized open reading frame in region B has been implicated in this regulation and designated as Integrating multiple copies of in the genome at tandem, suppresses the growth of recipient strain on L-sorbose, establishing it as a repressor of gene.

Conclusion: This finding completes the identification of regulators in SUR1 pathway. This result paves the way to study the underlying molecular mechanisms of gene regulation that in-turn helps to understand stress induced aneuploidy.