Cloning of the Saccharomyces cerevisiae gene whose overexpression overcomes the effects of HM-1 killer toxin, which inhibits β-glucan synthesis

S. Kasahara, H. Yamada, T. Mio, Y. Shiratori, C. Miyamoto, T. Yabe, T. Nakajima, E. Ichishima, Y. Furuichi

    Research output: Contribution to journalArticlepeer-review

    43 Citations (Scopus)

    Abstract

    A gene whose overexpression can endow Saccharomyces cerevisiae cells with resistance to HM-1 killer toxin was cloned from an S. cerevisiae genomic library. This gene, designated HKR1 (Hansenula mrakii killer toxin-resistant gene 1), contains a 5.4-kb open reading frame. The predicted amino acid sequence of the protein specified by HKR1 indicates that the protein consists of 1,802 amino acids and is very rich in serine and threonine, which could serve as O-glycosylation sites. The protein also contains two hydrophobic domains at the N-terminal end and in the C-terminal half, which could function as a signal peptide and transmembrane domain, respectively. Hkr1p is found to contain an EF hand motif of the calcium-binding consensus sequence in the C-terminal cytoplasmic domain. Thus, Hkr1p is expected to be a calcium-binding, glycosylated type 1 membrane protein. Southern and Northern (RNA) analyses demonstrated that there is a single copy of the HKR1 gene in the S. cerevisiae genome, and the transcriptional level of HKR1 is extremely low. Gene disruption followed by tetrad analysis showed that HKR1 is an essential gene. Overexpression of the truncated HKR1 encoding the C-terminal half of Hkr1p made the cells more resistant to HM-1 killer toxin than the full-length HKR1 did, demonstrating that the C-terminal half of Hkr1p is essential for overcoming the effect of HM-1 killer toxin. Furthermore, overexpression of HKR1 increased the β-glucan content in the cell wall without affecting in vitro β-glucan synthase activity, suggesting that HKR1 regulates β-glucan synthesis in vivo.

    Original languageEnglish
    Pages (from-to)1488-1499
    Number of pages12
    JournalJournal of bacteriology
    Volume176
    Issue number5
    DOIs
    Publication statusPublished - 1994

    ASJC Scopus subject areas

    • Microbiology
    • Molecular Biology

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