Specificity of transmembrane protein palmitoylation in yeast

GONZALEZ MONTORO A; CHUMPÉN, S; QUIROGA, R; VALDEZ TAUBAS J

Puerto Madrin

Congreso; XLVI SAIB; 2010

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Palmitoylation is carried out by a family of palmitoyltransferases (PATs) characterized by the presence of a 50-residue long cysteine-rich domain (DHHC-CRD domain). Yeast has 7 members of the family and each of these proteins is thought to be responsible for the palmitoylation of a set of substrates. Substrate specificity of PATs is not yet fully understood. Several yeast PATs seem to have overlapping specificity, and for mammalian cells, it has been proposed that the machinery responsible for palmitoylating peripheral membrane proteins lacks specificity altogether. Here we investigate the specificity of transmembrane protein palmitoylation, which in the yeast S. cerevisiae, is carried out mostly by two PATs, Swf1 and Pfa4. We show that palmitoylation of transmembrane substrates requires specific PATs, since other yeast PATs cannot carry out Swf1 or Pfa4 functions. Furthermore, we find that Swf1 is highly specific for its substrates, as it is unable to substitute for other PATs. To identify where Swf1 specificity lies, we used a chimeric-gene strategy and carried out a bioinformatic survey to identify amino acids responsible for the determination of specificity (SDPs). Our results indicate that the DHHC domain might be involved in the determination of specificity. Finally, we show that the position of the cysteines in Tlg1, a Swf1 substrate, is important for their palmitoylation.