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Rapid analysis of protein farnesyltransferase substrate specificity using peptide libraries and isoprenoid
Yen-Chih Wang1, Jonathan K Dozier, Lorena S Beese
1Department of Chemistry, University of Minnesota , Minneapolis, Minnesota 55455, United States.
Abstract:
Protein farnesytransferase (PFTase) catalyzes the farnesylation of proteins with a carboxy-terminal tetrapeptide sequence denoted as a Ca1a2X box. To explore the specificity of this enzyme, an important therapeutic target, solid-phase peptide synthesis in concert with a peptide inversion strategy was used to prepare two libraries, each containing 380 peptides. The libraries were screened using an alkyne-containing isoprenoid analogue followed by click chemistry with biotin azide and subsequent visualization with streptavidin-AP. Screening of the CVa2X and CCa2X libraries with Rattus norvegicus PFTase revealed reaction by many known recognition sequences as well as numerous unknown ones. Some of the latter occur in the genomes of bacteria and viruses and may be important for pathogenesis, suggesting new targets for therapeutic intervention. Screening of the CVa2X library with alkyne-functionalized isoprenoid substrates showed that those prepared from C10 or C15 precursors gave similar results, whereas the analogue synthesized from a C5 unit gave a different pattern of reactivity. Lastly, the substrate specificities of PFTases from three organisms (R. norvegicus, Saccharomyces cerevisiae, and Candida albicans) were compared using CVa2X libraries. R. norvegicus PFTase was found to share more peptide substrates with S. cerevisiae PFTase than with C. albicans PFTase. In general, this method is a highly efficient strategy for rapidly probing the specificity of this important enzyme.
Insights
Researchers explored protein farnesyltransferase (PFTase) specificity using peptide libraries. New recognition sequences were identified, including potential therapeutic targets in bacteria and viruses.
Area of Science:
- Biochemistry
- Enzymology
- Molecular Biology
Background:
- Protein farnesyltransferase (PFTase) is a key enzyme in protein modification.
- PFTase catalyzes the farnesylation of proteins containing a specific C-terminal tetrapeptide motif (Ca1a2X box).
- Understanding PFTase specificity is crucial as it represents an important therapeutic target.
Purpose of the Study:
- To explore the substrate specificity of PFTase.
- To identify novel PFTase recognition sequences.
- To investigate potential new therapeutic targets.
Main Methods:
- Solid-phase peptide synthesis and peptide inversion strategy were employed to create two peptide libraries (380 peptides each).
- Screening utilized an alkyne-containing isoprenoid analogue, click chemistry with biotin azide, and streptavidin-AP visualization.
- Comparative analysis of PFTase substrate specificities across different organisms (Rattus norvegicus, Saccharomyces cerevisiae, Candida albicans).
Main Results:
- Screening of CVa2X and CCa2X libraries with Rattus norvegicus PFTase identified known and numerous novel recognition sequences.
- Some novel sequences were found in bacterial and viral genomes, suggesting potential roles in pathogenesis.
- Substrate specificity varied with isoprenoid precursor chain length (C10/C15 vs. C5).
- Rattus norvegicus PFTase shared more peptide substrates with Saccharomyces cerevisiae PFTase than with Candida albicans PFTase.
Conclusions:
- The developed method is highly efficient for rapidly probing PFTase specificity.
- Novel PFTase substrates identified may represent new therapeutic targets, particularly in microbial pathogens.
- Comparative enzymatic studies reveal evolutionary relationships in PFTase substrate recognition.
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