A Mutation in the Schizosaccharomyces pombe rae1 Gene Causes Defects in Poly(A)+ RNA Export and in the Cytoskeleton

Julie A Brown,Anekella Bharathi,Anil Ghosh,William Whalen,Ellen Fitzgerald,Ravi Dhar

doi:10.1074/jbc.270.13.7411

Julie A Brown, Anekella Bharathi + Show 4 more

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https://doi.org/10.1074/jbc.270.13.7411

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Abstract

A collection of fission yeast Schizosaccharomyces pombe conditional mutants was screened for defective nucleocytoplasmic transport of poly(A)+ RNA by fluorescence in situ hybridization. We identified a temperature-sensitive mutant that accumulated poly(A)+ RNA in the nucleus and have named it rae1-1, for ribonucleic acid export. All rae1-1 cells exhibit the defect in poly(A)+ RNA export within 30 min following a shift to the non-permissive temperature. In addition, in the rae1-1 mutant, actin and tubulin become disorganized, and cells undergo an irreversible cycle arrest. Results from experiments in which rae1-1 cells were arrested in various phases of the cell division cycle and then shifted to nonpermissive temperature suggest that cells are particularly vulnerable to loss of rae1 function during G2/M. However, the inability to export RNA from the nucleus to the cytoplasm was not limited to a particular phase of the cell division cycle. The rae1 gene was isolated by complementation and encodes a predicted protein of 352 amino acids with four beta-transducin/WD40 repeats.

Highlights

A collection of fission yeast Schiaoeaceharomyces pombe conditional mutants was screened for defective nucleocytoplasmic transport of poly(A)+ RNA by fluorescence in situ hybridization
After 5 min at the nonpermissive temperature, the poly(A) + RNA signal was brighter in the nucleus than in the cytoplasm in approximately 30% of rael-L cells (Fig. 1, panels E and F)
We h a ve ide ntified as. pomb e tem perature-se ns itive mut ant that is defecti ve in ex port of polyfA)" RNA fro m the nucleus to the cytoplasm

Summary

Introduction

A collection of fission yeast Schiaoeaceharomyces pombe conditional mutants was screened for defective nucleocytoplasmic transport of poly(A)+ RNA by fluorescence in situ hybridization. Mutations in the S. cerevisiae SRMl / PRP20 / MTRl gene cause defects in RNA production that are similar to RNAl [4,5,6]. This gene is a member of a family of related genes that includes the hamster RCCl gene [7] andpiml in S. pombe [8]. RCel andpiml were identified as regulators of chromatin condensation during the cell division cycle [8,9,10] and have since been shown to affect nucleocytoplasmic transport of polyrA) + RNA [11]. To understand the process of RNA transport, we screened a collection of temperaturesensitive S. pombe mutants for conditional RNA export defects

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