Martinez-Rucobo FW, et al. (2009) Yeast chitin synthase 2 activity is modulated by proteolysis and phosphorylation. Biochem J 417(2):547-54
Abstract: Saccharomyces cerevisiae chitin synthase 2 (Chs2) synthesizes the primary septum after mitosis is completed. It is essential for proper cell separation and expected to be highly regulated. We have expressed Chs2 and a mutant lacking the N-terminal region in Pichia pastoris in an active form at high levels. Both constructs show a pH and cation dependence similar to the wild-type enzyme, as well as increased activity after trypsin treatment. Using further biochemical analysis, we have identified two mechanisms of chitin synthase regulation. First, it is hyperactivated by a soluble yeast protease. This protease is expressed during logarithmic growth phase, when budding cells require Chs2 activity. Secondly, LC-MS/MS experiments on purified Chs2 identify twelve phosphorylation sites, all in the N-terminal domain. Four of them show the perfect sequence motif for phosphorylation by the cyclin-dependent kinase Cdk1. As we also show that phosphorylation of the N-terminal domain is important for Chs2 stability, these sites might play an important role in the cell cycle-dependent degradation of the enzyme, and thus in cell division.
|Status: Published||Type: Journal Article||PubMed ID: 18823281|
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