Professor Mark Distefano

CSENG Chemistry
College of Science & Engineering
Twin Cities
Project Title: 
Enzymology and Biotechnology of Protein Prenylation

Protein prenylation is an irreversible covalent post-translational modification found in all eukaryotic cells, comprising of farnesylation and geranylgeranylation. Three prenyltransferase enzymes catalyze this modification. Farnesyltransferase (FTase) and geranylgeranyltransferase type 1 (GGTase-I) catalyze attachment of a single farnesyl (15 carbon), or geranylgeranyl (20 carbon) isoprenoid group, respectively, to a cysteine residue located in a C-terminal consensus sequence commonly known as “CaaX box", where “C” is cysteine, “a” generally represents an aliphatic amino acid and the “X” residue is largely responsible for determining which isoprenoid is attached to the protein target. Proteins prenylated with FTase and GGTase-I typically undergo two additional processing steps. First, the C-terminal aaX tripeptide is cleaved from the newly prenylated CaaX protein by an endoprotease, either Ras-converting enzyme 1 (Rce1p) or Ste24p. This is followed by methylation of the prenylcysteine residue at the new C-terminus by isoprenylcysteine carboxylmethyltransferase (Icmt). This three-step process increases protein hydrophobicity, and often leads to plasma membrane association. Prenylation serves as the first critical step for membrane targeting and binding, as well as mediating protein-protein interactions of a large number of Ras proteins; heterotrimeric G-proteins also require prenylation for activity.Significant interest in studying protein prenylation originally stemmed from the finding that this modification was necessary to maintain malignant activity of oncogenic Ras proteins although now it is known that prenylation is important in a wide ranges of diseases. These researchers are using computer-based methods for three subprojects within this area. They include:

  • Design of caging groups used to mask the activity of substrates and inhibitors of protein prenylation
  • Bioinformatic analysis of proteomic data obtained using probes that allow selective detection of prenylated proteins
  • Modeling of prenyltransferase structures to design mutations that alter substrate specificity and for the purpose of designing new inhibitors

Project Investigators

Reid Anderson
Taysir Bader
Professor Mark Distefano
Mohammad Mohsen Mahmoodi
Charuta Palsuledesai
Alexander Sarkis
Garrett Schey
Kiall Francis Suazo
Feng Xu
Yi Zhang
 
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