Differential involvement of multiple genes in the regulation of l sorbose utilisation in candida albicans

Abstract

Candida albicans is an opportunistic fungal pathogen responsible for nosocomial newlineinfections in humans. Although it resides as normal flora in healthy individuals, it can newlinecause an array of infections ranging from superficial oral infections to life-threatening newlinebloodstream infections in immuno-compromised individuals. Candida albicans newlinepossesses unique traits like morphological switching between yeast and hypha forms, newlinehighly dynamic genome involving in random karyotype changes like aneuploidy, loss newlineof heterozygosity (LOH), segmental duplications and iso-chromosome formation and a newlineunique sexual cycle (parasexual cycle) generating stable diploids from tetraploid newlineintermediates by concerted chromosome loss. These qualities assist in the pathogenicity newlineand adaptability in adverse conditions and various environmental cues. The karyotype newlinechanges frequently observed in C. albicans include trisomy of Chr3, iso-chromosome newlineformation of Chr5 (L) and Chr5 (R) in drug-resistant clinical isolates and monosomy of newlineChr5 in presence of L- sorbose. The growth of Candida on L-sorbose by losing one newlinecopy of Chr5 is well studied; here, the whole chromosome acts as a regulatory unit, newlinenegatively regulating the gene responsible for metabolizing L sorbose. newlineC. albicans, when grown on L sorbose, generates Sou + mutants after 14 days of newlineincubation. These positive colonies survive on L sorbose by losing one copy of newlinechromosome 5. Upon relieving the stress, the chromosome reverts to a diploid state, and newlinethe strain becomes Sou - . Previous studies identified scattered regulators (CSU s) on the newlineright arm of Chr5 in five putative regions (A, B, C, 135 and 139). These, CSU51 newline(region A), CSU53 (region 135) and CSU57 (region C), were identified in different newlinestudies. The present study analyzed the relationship between the regulators and the newlineSOU1 gene by molecular genetics approach.We observed that the SOU1 gene newlineregulation is dependent on the gene dosage of regulators. newline