Prenylation of Saccharomyces cerevisiae Chs4p Affects Chitin Synthase III activity and chitin chain length

Eukaryot Cell. 2007 Feb;6(2):328-36. doi: 10.1128/EC.00203-06. Epub 2006 Dec 1.

Abstract

Chs4p (Cal2/Csd4/Skt5) was identified as a protein factor physically interacting with Chs3p, the catalytic subunit of chitin synthase III (CSIII), and is indispensable for its enzymatic activity in vivo. Chs4p contains a putative farnesyl attachment site at the C-terminal end (CVIM motif) conserved in Chs4p of Saccharomyces cerevisiae and other fungi. Several previous reports questioned the role of Chs4p prenylation in chitin biosynthesis. In this study we reinvestigated the function of Chs4p prenylation. We provide evidence that Chs4p is farnesylated by showing that purified Chs4p is recognized by anti-farnesyl antibody and is a substrate for farnesyl transferase (FTase) in vitro and that inactivation of FTase increases the amount of unmodified Chs4p in yeast cells. We demonstrate that abolition of Chs4p prenylation causes a approximately 60% decrease in CSIII activity, which is correlated with a approximately 30% decrease in chitin content and with increased resistance to the chitin binding compound calcofluor white. Furthermore, we show that lack of Chs4p prenylation decreases the average chain length of the chitin polymer. Prenylation of Chs4p, however, is not a factor that mediates plasma membrane association of the protein. Our results provide evidence that the prenyl moiety attached to Chs4p is a factor modulating the activity of CSIII both in vivo and in vitro.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Chitin / metabolism*
  • Chitin Synthase / genetics
  • Chitin Synthase / isolation & purification
  • Chitin Synthase / metabolism*
  • Fungal Proteins / genetics
  • Fungal Proteins / isolation & purification
  • Fungal Proteins / metabolism*
  • Gene Expression Regulation, Fungal*
  • Protein Prenylation*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / isolation & purification
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Subcellular Fractions

Substances

  • Fungal Proteins
  • Saccharomyces cerevisiae Proteins
  • Chitin
  • Chitin Synthase