Isolation of 4-aminopyridine resistant mutants affecting alkali-insoluble glucan content of cell walls in <i>Saccharomyces cerevisiae</i>

Abstract

<i>Saccharomyces cerevisiae </i>cells when grown on synthetic medium plates containing 10 m<i>M</i> of 4-aminopyridine (4-AP) undergo cell lysis. Using an ethylmethane sulfonate mutagenesis (EMS) screen, 4-AP resistant mutants (<i>apr</i>)<i> </i>were isolated which could grow on inhibitory concentration of 4-AP. Eighty mutants were obtained that were recessive, monogenic and

formed two complementation groups. To identify genes, whose products might be interacting with the <i>apr </i>loci, extragenic suppressors were isolated, which reverted 4-AP resistance phenotype of <i>apr </i>mutants. The suppressors, when genetically characterized, were found to be recessive and represented two loci with overlapping functions. Representative alleles from

<i><span style="font-size:12.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";mso-ansi-language:en-in;mso-fareast-language:="" en-in;mso-bidi-language:hi"="">apr </span></i><span style="font-size:12.0pt; line-height:115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:hi"="">mutants were analyzed for cell wall composition. They were found to have a higher amount of alkali-insoluble glucan signifying the role of alkali-insoluble glucan in cell wall maintenance.</span>