Evidence for control of nitrogen metabolism by a START-dependent mechanism in<Emphasis Type="Italic"> Saccharomyces cerevisiae</Emphasis>

It is generally thought that cell growth and metabolism regulate cell division and not vice versa. Here, we examined Saccharomyces cerevisiae cells growing under conditions of continuous culture in a chemostat. We found that loss of G1 cyclins, or inactivation of the cyclin-dependent kinase Cdc28p, reduced the activity of glutamate synthase (Glt1p), a key enzyme in nitrogen assimilation. We also present evidence indicating that the G1 cyclin-dependent control of Glt1p may involve Jem1p, a DnaJ-type chaperone. Our results suggest that completion of START may be linked to nitrogen metabolism.Communicated by C. P. Hollenberg