Novel biosynthetic pathway for sulfur amino acids in Cryptococcus neoformans
| Autor: | Naruhiko Ishiwada, Akio Toh-e, Akira Watanabe, Kiminori Shimizu, Misako Ohkusu, Katsuhiko Kamei |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
Male Sulfur metabolism Transsulfuration Transsulfuration pathway Saccharomyces cerevisiae Cysteine synthase Microbiology 03 medical and health sciences chemistry.chemical_compound Methionine Sulfur assimilation Genetics Serine Animals Cysteine Hydrogen Sulfide Cryptococcus neoformans Cysteine Synthase Mice Inbred ICR biology Virulence General Medicine biology.organism_classification Amino Acids Sulfur 030104 developmental biology Biochemistry chemistry Agrobacterium tumefaciens Mutagenesis Models Animal biology.protein Genome Fungal Sulfur |
| Zdroj: | Current genetics. 64(3) |
| ISSN: | 1432-0983 |
| Popis: | We elucidated a unique feature of sulfur metabolism in Cryptococcus neoformans. C. neoformans produces cysteine solely by the O-acetylserine pathway that consists of serine-O-acetyl transferase and cysteine synthase. We designated the gene encoding the former enzyme CYS2 (locus tag CNE02740) and the latter enzyme CYS1 (locus tag CNL05880). The cys1Δmutant strain was found to be avirulent in a murine infection model. Methionine practically does not support growth of the cys1Δ strain, and cysteine does not serve as a methionine source, indicating that the transsulfuration pathway does not contribute to sulfur amino acid synthesis in C. neoformans. Among the genes encoding enzymes catalyzing the reactions from homoserine to methionine, the gene corresponding to the Saccharomyces cerevisiae MET17 encoding O-acetylhomoserine sulfhydrylase (Met17p) had remained to be identified in C. neoformans. By genetic analysis of Met- mutants obtained by Agrobacterium tumefaciens-mediated mutagenesis, we concluded that Cnc01220, most similar to Str2p (36% identity), cystathionine-γ-synthase, in the Saccharomyces genome, is the C. neoformans version of O-acetylhomoserine sulfhydrylase. We designated CNC01220 as MET17. The C. neoformans met3Δ mutant defective in the first step of the sulfate assimilation pathway, sulfate adenylyltransferase, barely uses methionine as a sulfur source, whereas it uses cysteine efficiently. The poor utilization of methionine by the met3Δ mutant is most probably due to the absence of the transsulfuration pathway, causing an incapability of C. neoformans to produce cysteine and hydrogen sulfide from methionine. When cysteine is used as a sulfur source, methionine is likely produced de novo by using hydrogen sulfide derived from cysteine via an unidentified pathway. Altogether, the unique features of sulfur amino acid metabolism in C. neoformans will make this fungus a valuable experimental system to develop anti-fungal agents and to investigate physiology of hydrogen sulfide. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full text from SpringerLink