Cell cycle regulation mechanism in pathogenic yeast, Cryptococcus neoformans: Structure‐function relationship of G1 and G1/S cyclins homologue CnCln1

Abstract

Cryptococcus neoformans is an opportunistic pathogen of worldwide distribution and responsible for life‐threatening infections among immunecompromised persons. We have reported that the cell cycle behavior of this yeast is different from the cell cycle control model exhibited by the model yeast Saccharomyces cerevisiae. The molecular characterization and physiological roles of the two main eukaryotic cell cycle genes, C. neoformans Cyclin‐dependent kinase 1 (CnCdk1) and its G1 cyclin, in the pathogenic yeast, will be reported and discussed. Only a single Cdk1‐related G1 and G1/S cyclin homologue was found in the genome sequence of C. neoformans and designated it CnCln1. Surprisingly, CnCln1 was not only able to complement the function of the G1 cyclins of S. cerevisiae, such as ScCln3, but also the G1/S cyclins of S. cerevisiae, such as ScCln1 and ScCln2. Our in silico analysis demonstrated that the CnCln1/ScCdk1 complex was more stable than any of the yeast cyclin and ScCdk1 complexes. Thus, these results are consistent with in vitro analysis that has revealed the flexible functional capacity of CnCln1 as a Cdk1‐related G1 and G1/S cyclins of S. cerevisiae. This work was supported by Grants‐in‐Aid for Scientific Research from the Ministry of Education, Science, Sports, and Culture of Japan.