Mutations in a peptidylprolyl-cis/trans-isomerase gene lead to a defect in 3'-end formation of a pre-mRNA in Saccharomyces cerevisiae.
In a genetic screen aimed at the identification of trans-acting factors involved in mRNA 3'-end processing of budding yeast, we have previously isolated two temperature-sensitive mutants with an apparent defect in the 3'-end formation of a plasmid-derived pre-mRNA. Surprisingly, both mutants were rescued by the essential gene ESS1/PTF1 that encoded a putative peptidylprolyl-cis/trans-isomerase (PPIase) (Hani, J., Stumpf, G., and Domdey, H. (1995) FEBS Lett. 365, 198-202). Such enzymes, which catalyze the cis/trans-interconversion of peptide bonds N-terminal of prolines, are suggested to play a role in protein folding or trafficking. Here we report that Ptf1p shows PPIase activity in vitro, displaying an unusual substrate specificity for peptides with phosphorylated serine and threonine residues preceding proline. Both mutations were found to result in amino acid substitutions of highly conserved residues within the PPIase domain, causing a marked decrease in PPIase activity of the mutant enzymes. Our results are suggestive of a so far unknown involvement of a PPIase in mRNA 3'-end formation in Saccharomyces cerevisiae.
Hani
J
J
Genzentrum der Ludwig-Maximilians-Universität München, Feodor-Lynen Strasse 25, 81377 München, Germany.
Schelbert
B
B
Bernhardt
A
A
Domdey
H
H
Fischer
G
G
Wiebauer
K
K
Rahfeld
J U
JU
D000591:Amino Acid Isomerases / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D017931:DNA Primers; D008969:Molecular Sequence Data; D009154:Mutation; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D019696:Peptidylprolyl Isomerase / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D012322:RNA Precursors / Q000235:genetics*; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D017931:DNA Primers; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D012322:RNA Precursors; D012333:RNA, Messenger; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000591:Amino Acid Isomerases; C000606845:ESS1 protein, S cerevisiae; D019696:Peptidylprolyl Isomerase