scholarly journals The Cs sec mutants of Escherichia coli reflect the cold sensitivity of protein export itself.

Genetics ◽  
1993 ◽  
Vol 133 (4) ◽  
pp. 763-773 ◽  
Author(s):  
K J Pogliano ◽  
J Beckwith
Keyword(s):  
Escherichia Coli ◽  
Signal Sequence ◽  
Thermal Sensitivity ◽  
Specific Interaction ◽  
Protein Export ◽  
Cold Sensitivity ◽  
Lethal Mutations ◽  
Cold Sensitive ◽  
Sec Proteins ◽  
Striking Effect

Abstract We have found that temperature can have a striking effect upon protein export in Escherichia coli, suggesting that there is a cold-sensitive step in the protein export pathway. Cs mutations comprise the largest class of mutations affecting the membrane-localized Sec proteins SecD, SecE, SecF and SecY. Although some of these mutations could encode cold-labile proteins, this is unlikely to account for the Cs phenotype of most export mutants, as mutations which simply produce lower amounts of SecE protein have the same phenotype. Certain signal sequence mutations affecting maltose binding protein are also cold sensitive for export. These effects appear to arise by a specific interaction of cold with certain export defects. We believe that the Cs sec mutations are representative of a large class of conditional lethal mutations, whose conditional phenotype reflects an underlying thermal sensitivity of the process in which they are involved.

scholarly journals secG and Temperature Modulate Expression of Azide-Resistant and Signal Sequence Suppressor Phenotypes of Escherichia coli secA Mutants

1998 ◽  
Vol 180 (23) ◽  
pp. 6419-6423 ◽  
Author(s):  
Visvanathan Ramamurthy ◽  
Vesna Dapíc ◽  
Donald Oliver
Keyword(s):  
Escherichia Coli ◽  
Direct Effect ◽  
Protein Translocation ◽  
Signal Sequence ◽  
Protein Export ◽  
Null Mutant ◽  
Inner Membrane ◽  
Membrane Interaction ◽  
Cold Sensitive ◽  
Azide Resistance

ABSTRACT SecA is a dynamic protein that undergoes ATP-dependent membrane cycling to drive protein translocation across the Escherichia coli inner membrane. To understand more about this process, azide-resistant (azi) and signal sequence suppressor (prlD) alleles of secA were studied. We found that azide resistance is cold sensitive because of a direct effect on protein export, suggesting that SecA-membrane interaction is regulated by an endothermic step that is azide inhibitable. secGfunction is required for expression of azide-resistant and signal sequence suppressor activities of azi and prlDalleles, and in turn, these alleles suppress cold-sensitive and export-defective phenotypes of a secG null mutant. These remarkable genetic observations support biochemical data indicating that SecG promotes SecA membrane cycling and that this process is dependent on an endothermic change in SecA conformation.

scholarly journals Suppression of ΔbipA Phenotypes in Escherichia coli by Abolishment of Pseudouridylation at Specific Sites on the 23S rRNA

2008 ◽  
Vol 190 (23) ◽  
pp. 7675-7683 ◽  
Author(s):  
Karthik Krishnan ◽  
Ann M. Flower
Keyword(s):  
Escherichia Coli ◽  
Target Genes ◽  
Regulatory Protein ◽  
Elongation Factor ◽  
Direct Interaction ◽  
Cold Sensitivity ◽  
23S Rrna ◽  
Pseudouridine Synthase ◽  
Suppressor Effect ◽  
Cold Sensitive

ABSTRACT The BipA protein of Escherichia coli has intriguing similarities to the elongation factor subfamily of GTPases, including EF-Tu, EF-G, and LepA. In addition, phenotypes of a bipA deletion mutant suggest that BipA is involved in regulation of a variety of pathways. These two points have led to speculation that BipA may be a novel regulatory protein that affects efficient translation of target genes through direct interaction with the ribosome. We isolated and characterized suppressors of the cold-sensitive growth phenotype exhibited by ΔbipA strains and identified insertion mutations in rluC. The rluC gene encodes a pseudouridine synthase responsible for pseudouridine modification of 23S rRNA at three sites, all located near the peptidyl transferase center. Deletion of rluC not only suppressed cold sensitivity but also alleviated the decrease in capsule synthesis exhibited by bipA mutants, suggesting that the phenotypic effects of BipA are manifested through an effect on the ribosome. The suppressor effect is specific to rluC, as deletion of other rlu genes did not relieve cold sensitivity, and further, more than a single pseudouridine residue is involved, as alteration of single residues did not produce suppressors. These results are consistent with a role for BipA in either the structure or the function of the ribosome and imply that wild-type ribosomes are dependent on BipA for efficient expression of target mRNAs and that the lack of pseudouridylation at these three sites renders the ribosomes BipA independent.

scholarly journals TEMPERATURE-SENSITIVE MUTATIONS IN DROSOPHILA MELANOGASTER. XVII. HEAT- AND COLD-SENSITIVE LETHALS ON CHROMOSOME 3

Genetics ◽  
1973 ◽  
Vol 74 (3) ◽  
pp. 509-520
Author(s):  
S Elaine Tasaka ◽  
David T Suzuki
Keyword(s):  
Drosophila Melanogaster ◽  
Ethyl Methanesulfonate ◽  
Cold Sensitivity ◽  
Chromosome 3 ◽  
Temperature Sensitive ◽  
Single Mutation ◽  
Physical Length ◽  
Lethal Mutations ◽  
Genetic Length ◽  
Cold Sensitive

ABSTRACT Ethyl methanesulfonate-treated third chromosome of Drosophila melanogaster were tested for the presence of dominant and recessive temperature-sensitive lethal mutations at 17°, 22° and 29°C. Out of 1,176 chromosomes tested, no dominant ts lethals, 21 heat-sensitive, 22 cold-sensitive and 10 heat-cold-sensitive lethals were recovered. Heat-cold sensitivity was produced by a single mutation in all cases. Sixty-two percent of the ts lethals were fertile as homozygotes in both sexes. Surprisingly, 88% of the ts lethals mapped between st and Sb, a region straddling the centromere and estimated to comprise 12.9% of the genetic length and 55% of the physical length of chromosome 3. All but one of the heat- and cold-sensitive lethals complemented with each other at their respective restrictive temperatures.

scholarly journals A signal sequence is not required for protein export in prlA mutants of Escherichia coli.

1993 ◽  
Vol 12 (3) ◽  
pp. 879-888 ◽  
Author(s):  
A.I. Derman ◽  
J.W. Puziss ◽  
P.J. Bassford ◽  
J. Beckwith
Keyword(s):  
Escherichia Coli ◽  
Signal Sequence ◽  
Protein Export

Suppressors of a Cold-Sensitive Mutation in Yeast U4 RNA Define Five Domains in the Splicing Factor Prp8 That Influence Spliceosome Activation

Genetics ◽  
2000 ◽  
Vol 155 (4) ◽  
pp. 1667-1682 ◽  
Author(s):  
Andreas N Kuhn ◽  
David A Brow
Keyword(s):  
Large Scale ◽  
Splicing Factor ◽  
Cold Sensitivity ◽  
Splicing Factors ◽  
Loss Of Function ◽  
U1 Snrnp ◽  
Snrnp Protein ◽  
Cold Sensitive ◽  
Spliceosome Activation ◽  
U4 Rna

AbstractThe highly conserved splicing factor Prp8 has been implicated in multiple stages of the splicing reaction. However, assignment of a specific function to any part of the 280-kD U5 snRNP protein has been difficult, in part because Prp8 lacks recognizable functional or structural motifs. We have used a large-scale screen for Saccharomyces cerevisiae PRP8 alleles that suppress the cold sensitivity caused by U4-cs1, a mutant U4 RNA that blocks U4/U6 unwinding, to identify with high resolution five distinct regions of PRP8 involved in the control of spliceosome activation. Genetic interactions between two of these regions reveal a potential long-range intramolecular fold. Identification of a yeast two-hybrid interaction, together with previously reported results, implicates two other regions in direct and indirect contacts to the U1 snRNP. In contrast to the suppressor mutations in PRP8, loss-of-function mutations in the genes for two other splicing factors implicated in U4/U6 unwinding, Prp44 (Brr2/Rss1/Slt22/Snu246) and Prp24, show synthetic enhancement with U4-cs1. On the basis of these results we propose a model in which allosteric changes in Prp8 initiate spliceosome activation by (1) disrupting contacts between the U1 snRNP and the U4/U6-U5 tri-snRNP and (2) orchestrating the activities of Prp44 and Prp24.

scholarly journals Characterization and in Vivo Cloning of prlC, a Suppressor of Signal Sequence Mutations in Escherichia coli K12

Genetics ◽  
1987 ◽  
Vol 116 (4) ◽  
pp. 513-521
Author(s):  
Nancy J Trun ◽  
Thomas J Silhavy
Keyword(s):  
Escherichia Coli ◽  
Genetic Mapping ◽  
Signal Sequence ◽  
Illegitimate Recombination ◽  
Mutant Phenotype ◽  
E Coli ◽  
Physical Location ◽  
Sequence Deletion ◽  
New Alleles

ABSTRACT The prlC gene of E. coli was originally identified as an allele, prlC1, which suppresses certain signal sequence mutations in the genes for several exported proteins. We have isolated six new alleles of prlC that also confer this phenotype. These mutations can be placed into three classes based on the degree to which they suppress the lamBsignal sequence deletion, lamBs78. Genetic mapping reveals that the physical location of the mutations in prlC correlates with the strength of the suppression, suggesting that different regions of the gene can be altered to yield a suppressor phenotype. We also describe an in vivo cloning procedure using λplacMu9H. The procedure relies on transposition and illegitimate recombination to generate a specialized transducing phage that carries prlC1. This method should be applicable to any gene for which there is a mutant phenotype.

Sign in / Sign up

Export Citation Format

Share Document