ABSTRACT
The Ess1/Pin1 peptidyl-prolyl isomerase (PPIase) is thought to control mitosis by binding to cell cycle regulatory proteins and altering their activity. Here we isolate temperature-sensitive ess1 mutants and identify six multicopy suppressors that rescue their mitotic-lethal phenotype. None are cell cycle regulators. Instead, five encode proteins involved in transcription that bind DNA, modify chromatin structure or are regulatory subunits of RNA polymerase II. A sixth suppressor, cyclophilin A, is a member of a distinct family of PPIases that are targets of immuno suppressive drugs. We show that the expression of some but not all genes is decreased in ess1 mutants, and that Ess1 interacts with the C-terminal domain (CTD) of RNA polymerase II in vitro and in vivo. The results forge a strong link between PPIases and the transcription machinery and suggest a new model for how Ess1/Pin1 controls mitosis. In this model, Ess1 binds and isomerizes the CTD of RNA polymerase II, thus altering its interaction with proteins required for transcription of essential cell cycle genes.
Subject(s)
Chromatin/metabolism , Peptidylprolyl Isomerase/metabolism , Saccharomyces cerevisiae Proteins , Saccharomyces cerevisiae/enzymology , Saccharomyces cerevisiae/genetics , Transcription Factors/metabolism , Transcription, Genetic , Amino Acid Sequence , Animals , Chromatin/chemistry , Chromatin/genetics , Drosophila/enzymology , Drosophila Proteins , Fungal Proteins/metabolism , Gene Expression Regulation, Fungal/drug effects , Humans , Immunophilins/metabolism , Mediator Complex , Mitosis , Models, Biological , Models, Molecular , Molecular Sequence Data , NIMA-Interacting Peptidylprolyl Isomerase , Peptidylprolyl Isomerase/chemistry , Peptidylprolyl Isomerase/genetics , Phenotype , Protein Binding , Protein Structure, Tertiary , RNA Polymerase II/chemistry , RNA Polymerase II/metabolism , Saccharomyces cerevisiae/cytology , Sequence Alignment , Structure-Activity Relationship , Suppression, Genetic/genetics , Tacrolimus Binding Proteins , Transcription, Genetic/geneticsABSTRACT
An alkalophilic hyperproducer of alkaline protease, Bacillus sp. NG312, was isolated, and the enzyme showed maximum activity at pH 11.0 and 60 degrees C. The temperature optimum was increased by 10 degrees C in presence of Ca2+. The crude enzyme was found to have half-life of 11 d at 37 degrees C and maximum stability at pH 9.0-10.0. It also exhibited very good stability in presence of detergent components and some locally available commercial detergent powders.
