Suppressors of Clathrin Deficiency: Overexpression of Ubiquitin Rescues Lethal Strains of Clathrin-Deficient Saccharomyces cerevisiae

Karen K. Nelson, Sandra Lemmon

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

Clathrin-mediated vesicular transport is important for normal growth of the yeast Saccharomyces cerevisiae. Previously, we identified a genetic locus (SCD1) that influences the ability of clathrin heavy-chain-deficient (Chc-) yeast cells to survive. With the scd1-v allele, Chc- yeast cells are viable but grow poorly; with the scd1-i allele, Chc- cells are in viable. To identify the SCD1 locus and other genes that can rescue chc1Δ scd1-i cells to viability, a multicopy suppressor selection strategy was developed. A strain of scd1-i genotype carrying the clathrin heavy-chain gene under GAL1 control (GAL1:CHC1) was transformed with a YEp24 yeast genomic library, and colonies that could grow on glucose were selected. Plasmids from six distinct genetic loci, none of which encoded CHC1, were recovered. One of the suppressor loci was shown to be UBI4, the polyubiquitin gene. UBI4 rescues only in high copy number and is not allelic to SCD1. The conjugation of ubiquitin to intracellular proteins can mediate their selective degradation. Since UBI4 is required for survival of yeast cells under stress and is induced during starvation, ubiquitin expression in GAL1:.CHC1 cells was examined. After a shift to growth on glucose to repress synthesis of clathrin heavy chains, UBI4 mRNA levels were elevated >10-fold, whereas the quantity of free ubiquitin declined severalfold relative to that of Chc+ cells. In addition, novel higher-molecular-weight ubiquitin conjugates appeared in clathrin-deficient cells. We suggest that higher levels of ubiquitin are required for turnover of mislocalized or improperly processed proteins that accumulate in the absence of clathrin and that ubiquitin may play a general role in turnover of proteins in the secretory or endocytic pathway.

Original languageEnglish
Pages (from-to)521-532
Number of pages12
JournalMolecular and Cellular Biology
Volume13
Issue number1
StatePublished - Jan 1 1993
Externally publishedYes

Fingerprint

Clathrin Heavy Chains
Clathrin
Ubiquitin
Saccharomyces cerevisiae
Yeasts
Genetic Loci
Cell Survival
Alleles
Polyubiquitin
Genes
Glucose
Proteins
Genomic Library
Growth
Starvation
Plasmids
Molecular Weight
Genotype
Messenger RNA

ASJC Scopus subject areas

  • Cell Biology
  • Genetics
  • Molecular Biology

Cite this

@article{98d5684b28ae42e695772e5275dc2605,
title = "Suppressors of Clathrin Deficiency: Overexpression of Ubiquitin Rescues Lethal Strains of Clathrin-Deficient Saccharomyces cerevisiae",
abstract = "Clathrin-mediated vesicular transport is important for normal growth of the yeast Saccharomyces cerevisiae. Previously, we identified a genetic locus (SCD1) that influences the ability of clathrin heavy-chain-deficient (Chc-) yeast cells to survive. With the scd1-v allele, Chc- yeast cells are viable but grow poorly; with the scd1-i allele, Chc- cells are in viable. To identify the SCD1 locus and other genes that can rescue chc1Δ scd1-i cells to viability, a multicopy suppressor selection strategy was developed. A strain of scd1-i genotype carrying the clathrin heavy-chain gene under GAL1 control (GAL1:CHC1) was transformed with a YEp24 yeast genomic library, and colonies that could grow on glucose were selected. Plasmids from six distinct genetic loci, none of which encoded CHC1, were recovered. One of the suppressor loci was shown to be UBI4, the polyubiquitin gene. UBI4 rescues only in high copy number and is not allelic to SCD1. The conjugation of ubiquitin to intracellular proteins can mediate their selective degradation. Since UBI4 is required for survival of yeast cells under stress and is induced during starvation, ubiquitin expression in GAL1:.CHC1 cells was examined. After a shift to growth on glucose to repress synthesis of clathrin heavy chains, UBI4 mRNA levels were elevated >10-fold, whereas the quantity of free ubiquitin declined severalfold relative to that of Chc+ cells. In addition, novel higher-molecular-weight ubiquitin conjugates appeared in clathrin-deficient cells. We suggest that higher levels of ubiquitin are required for turnover of mislocalized or improperly processed proteins that accumulate in the absence of clathrin and that ubiquitin may play a general role in turnover of proteins in the secretory or endocytic pathway.",
author = "Nelson, {Karen K.} and Sandra Lemmon",
year = "1993",
month = "1",
day = "1",
language = "English",
volume = "13",
pages = "521--532",
journal = "Molecular and Cellular Biology",
issn = "0270-7306",
publisher = "American Society for Microbiology",
number = "1",

}

TY - JOUR

T1 - Suppressors of Clathrin Deficiency

T2 - Overexpression of Ubiquitin Rescues Lethal Strains of Clathrin-Deficient Saccharomyces cerevisiae

AU - Nelson, Karen K.

AU - Lemmon, Sandra

PY - 1993/1/1

Y1 - 1993/1/1

N2 - Clathrin-mediated vesicular transport is important for normal growth of the yeast Saccharomyces cerevisiae. Previously, we identified a genetic locus (SCD1) that influences the ability of clathrin heavy-chain-deficient (Chc-) yeast cells to survive. With the scd1-v allele, Chc- yeast cells are viable but grow poorly; with the scd1-i allele, Chc- cells are in viable. To identify the SCD1 locus and other genes that can rescue chc1Δ scd1-i cells to viability, a multicopy suppressor selection strategy was developed. A strain of scd1-i genotype carrying the clathrin heavy-chain gene under GAL1 control (GAL1:CHC1) was transformed with a YEp24 yeast genomic library, and colonies that could grow on glucose were selected. Plasmids from six distinct genetic loci, none of which encoded CHC1, were recovered. One of the suppressor loci was shown to be UBI4, the polyubiquitin gene. UBI4 rescues only in high copy number and is not allelic to SCD1. The conjugation of ubiquitin to intracellular proteins can mediate their selective degradation. Since UBI4 is required for survival of yeast cells under stress and is induced during starvation, ubiquitin expression in GAL1:.CHC1 cells was examined. After a shift to growth on glucose to repress synthesis of clathrin heavy chains, UBI4 mRNA levels were elevated >10-fold, whereas the quantity of free ubiquitin declined severalfold relative to that of Chc+ cells. In addition, novel higher-molecular-weight ubiquitin conjugates appeared in clathrin-deficient cells. We suggest that higher levels of ubiquitin are required for turnover of mislocalized or improperly processed proteins that accumulate in the absence of clathrin and that ubiquitin may play a general role in turnover of proteins in the secretory or endocytic pathway.

AB - Clathrin-mediated vesicular transport is important for normal growth of the yeast Saccharomyces cerevisiae. Previously, we identified a genetic locus (SCD1) that influences the ability of clathrin heavy-chain-deficient (Chc-) yeast cells to survive. With the scd1-v allele, Chc- yeast cells are viable but grow poorly; with the scd1-i allele, Chc- cells are in viable. To identify the SCD1 locus and other genes that can rescue chc1Δ scd1-i cells to viability, a multicopy suppressor selection strategy was developed. A strain of scd1-i genotype carrying the clathrin heavy-chain gene under GAL1 control (GAL1:CHC1) was transformed with a YEp24 yeast genomic library, and colonies that could grow on glucose were selected. Plasmids from six distinct genetic loci, none of which encoded CHC1, were recovered. One of the suppressor loci was shown to be UBI4, the polyubiquitin gene. UBI4 rescues only in high copy number and is not allelic to SCD1. The conjugation of ubiquitin to intracellular proteins can mediate their selective degradation. Since UBI4 is required for survival of yeast cells under stress and is induced during starvation, ubiquitin expression in GAL1:.CHC1 cells was examined. After a shift to growth on glucose to repress synthesis of clathrin heavy chains, UBI4 mRNA levels were elevated >10-fold, whereas the quantity of free ubiquitin declined severalfold relative to that of Chc+ cells. In addition, novel higher-molecular-weight ubiquitin conjugates appeared in clathrin-deficient cells. We suggest that higher levels of ubiquitin are required for turnover of mislocalized or improperly processed proteins that accumulate in the absence of clathrin and that ubiquitin may play a general role in turnover of proteins in the secretory or endocytic pathway.

UR - http://www.scopus.com/inward/record.url?scp=0027390598&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0027390598&partnerID=8YFLogxK

M3 - Article

C2 - 8380227

AN - SCOPUS:0027390598

VL - 13

SP - 521

EP - 532

JO - Molecular and Cellular Biology

JF - Molecular and Cellular Biology

SN - 0270-7306

IS - 1

ER -