Isolation and characterization of KlUBP2, a ubiquitin hydrolase gene of Kluyveromyces lactis that can suppress a ts-mutation in CBF2, a gene encoding a centromeric protein of Saccharomyces cerevisiae

The Kluyveromyces lactis UBP2 gene was isolated as a suppressor of a temperature-sensitive mutation in CBF2, a gene coding for a centromere-binding protein of Saccharomyces cerevisiae. The UBP genes are hydrolases than can cleave a ubiquitin moiety from a protein substrate. KlUBP2 is not essential for growth since a disruption of the KlUBP2 gene had little effect, except for a slight decrease in the growth rate. The stability of centromere-containing plasmids was not influenced either. In addition to KlUBP2, five S. cerevisiae genes involved in the ubiquitination pathway could suppress the ts-mutation in the CBF2 gene, namely UBA1, UBA2, UBP1, UBP2 and YUH1, although YUH1 was the only one that could do this like KlUBP2 from a single-copy plasmid. Surprisingly, these genes encode proteins with antagonistic activity as two, UBA1 and UBA2, are ubiquitin-activating enzymes whereas the other three are de-ubiquitinating hydrolases.