Plant farnesyltransferase can restore yeast Ras signaling and mating

S. Yalovsky, C. E. Trueblood, K. L. Callan, J. O. Narita, S. M. Jenkins, J. Rine, W. Gruissem

Research output: Contribution to journalArticlepeer-review


Farnesyltransferase (FTase) is a heterodimeric enzyme that modifies a group of proteins, including Ras, in mammals and yeasts. Plant FTase α and β subunits were cloned from tomato and expressed in the yeast Saccharomyces cerevisiae to assess their functional conservation in farnesylating Ras and a-factor proteins, which are important for cell growth and mating. The tomato FTase β subunit (LeFTB) alone was unable to complement the growth defect of ram1Δ mutant yeast strains in which the chromosomal FTase β subunit gene was deleted, but coexpression of LeFTB with the plant α subunit gene (LeFTA) restored normal growth, Ras membrane association, and mating. LeFTB contains a novel 66-amino-acid sequence domain whose deletion reduces the efficiency of tomato FTase to restore normal growth to yeast ram1Δ strains. Coexpression of LeFTA and LeFTB in either yeast or insect cells yielded a functional enzyme that correctly farnesylated CaaX-motif-containing peptides. Despite their low degree of sequence homology, yeast and plant FTases shared similar in vivo and in vitro substrate specificities, demonstrating that this enzymatic modification of proteins with intermediates from the isoprenoid biosynthesis pathway is conserved in evolutionarily divergent eukaryotes.

Original languageEnglish
Pages (from-to)1986-1994
Number of pages9
JournalMolecular and Cellular Biology
Issue number4
StatePublished - Apr 1997
Externally publishedYes


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