Thecdr2+Gene Encodes a Regulator of G2/M Progression and Cytokinesis inSchizosaccharomyces pombe

Abstract

Schizosaccharomyces pombe cells respond to nutrient deprivation by altering G2/M cell size control. The G2/M transition is controlled by activation of the cyclin-dependent kinase Cdc2p. Cdc2p activation is regulated both positively and negatively. cdr2+was identified in a screen for regulators of mitotic control during nutrient deprivation. We have cloned cdr2+and have found that it encodes a putative serine-threonine protein kinase that is related to Saccharomyces cerevisiae Gin4p and S. pombe Cdr1p/Nim1p.cdr2+is not essential for viability, but cells lacking cdr2+are elongated relative to wild-type cells, spending a longer period of time in G2. Because of this property, upon nitrogen deprivationcdr2+mutants do not arrest in G1, but rather undergo another round of S phase and arrest in G2from which they are able to enter a state of quiescence. Genetic evidence suggests thatcdr2+acts as a mitotic inducer, functioning through wee1+, and is also important for the completion of cytokinesis at 36°C. Defects in cytokinesis are also generated by the overproduction of Cdr2p, but these defects are independent of wee1+, suggesting thatcdr2+encodes a second activity involved in cytokinesis.