title: Cryptococcus neoformans Ilv2p confers resistance to sulfometuron methyl and is required for survival at 37 degrees C and in vivo.
abstract: Acetolactate synthase catalyses the first common step in isoleucine and valine biosynthesis and is the target of several classes of inhibitors. The Cryptococcus neoformans ILV2 gene, encoding acetolactate synthase, was identified by complementation of a Saccharomyces cerevisiae ilv2 mutant. C. neoformans is highly resistant to the commercially available acetolactate synthase inhibitor, sulfometuron methyl (SM). Expression of C. neoformans ILV2 in S. cerevisiae conferred SM resistance, indicating that the SM resistance of C. neoformans is due, at least in part, to C. neoformans Ilv2p. The C. neoformans ILV2 gene was disrupted. The ilv2 mutants were auxotrophic for isoleucine and valine and the auxotrophy was satisfied by these amino acids only when proline, and not ammonium, was the nitrogen source, indicating nitrogen regulation of amino acid transport. ilv2 mutants rapidly lost viability at 37 degrees C and when starved for isoleucine and valine. Consistent with these phenotypes, an ilv2 mutant was avirulent and unable to survive in mice. Because C. neoformans Ilv2p is required for virulence and survival in vivo, inhibitors of branched-chain amino acid biosynthesis may make valuable antifungal agents.
authors.affiliation: Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Kingsbury
authors.affiliation: Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Zhonghui
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Tonya M
authors.initials: TM
authors.lastname: Ganous
authors.affiliation: Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Gary M
authors.initials: GM
authors.lastname: Cox
authors.affiliation: Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: McCusker
mesh_terms: D000095:Acetolactate Synthase / Q000037:antagonists & inhibitors / Q000235:genetics*; D000818:Animals; D003453:Cryptococcosis / Q000382:microbiology / Q000503:physiopathology; D003455:Cryptococcus neoformans / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development* / Q000472:pathogenicity; D025141:Drug Resistance, Fungal; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D005816:Genetic Complementation Test; D006801:Humans; D051379:Mice; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D013453:Sulfonylurea Compounds / Q000494:pharmacology*; D013696:Temperature; D014774:Virulence
chemical_list: D004791:Enzyme Inhibitors; D013453:Sulfonylurea Compounds; D000095:Acetolactate Synthase; C042031:sulfometuron methyl