scholarly journals Alteration of a Novel Dispensable Mitochondrial Ribosomal Small-Subunit Protein, Rsm28p, Allows Translation of Defective COX2 mRNAs

2005 ◽  
Vol 4 (2) ◽  
pp. 337-345 ◽  
Author(s):  
Elizabeth H. Williams ◽  
Nada Bsat ◽  
Nathalie Bonnefoy ◽  
Christine A. Butler ◽  
Thomas D. Fox
Keyword(s):  
Mitochondrial Gene ◽  
Carbon Sources ◽  
Small Subunit ◽  
Wild Type ◽  
Inner Mitochondrial Membrane ◽  
Positive Role ◽  
Mitochondrial Ribosomes ◽  
The Matrix ◽  
Triton X ◽  
Type Strains

ABSTRACT Mutations affecting the RNA sequence of the first 10 codons of the Saccharomyces cerevisiae mitochondrial gene COX2 strongly reduce translation of the mRNA, which encodes the precursor of cytochrome c oxidase subunit II. A dominant chromosomal mutation that suppresses these defects is an internal in-frame deletion of 67 codons from the gene YDR494w. Wild-type YDR494w encodes a 361-residue polypeptide with no similarity to proteins of known function. The epitope-tagged product of this gene, now named RSM28, is both peripherally associated with the inner surface of the inner mitochondrial membrane and soluble in the matrix. Epitope-tagged Rsm28p from Triton X-100-solubilized mitochondria sedimented with the small subunit of mitochondrial ribosomes in a sucrose gradient containing 500 mM NH4Cl. Complete deletion of RSM28 caused only a modest decrease in growth on nonfermentable carbon sources in otherwise wild-type strains and enhanced the respiratory defect of the suppressible cox2 mutations. The rsm28 null mutation also reduced translation of an ARG8 m reporter sequence inserted at the COX1, COX2, and COX3 mitochondrial loci. We tested the ability of RSM28-1 to suppress a variety of cox2 and cox3 mutations and found that initiation codon mutations in both genes were suppressed. We conclude that Rsm28p is a dispensable small-subunit mitochondrial ribosomal protein previously undetected in systematic investigations of these ribosomes, with a positive role in translation of several mitochondrial mRNAs.

Development of mutants of Gliocladium virens tolerant to benomyl

1990 ◽  
Vol 36 (7) ◽  
pp. 484-489 ◽  
Author(s):  
G. C. Papavizas ◽  
D. P. Roberts ◽  
K. K. Kim
Keyword(s):  
Carbon Source ◽  
Type Strain ◽  
Wild Type Strain ◽  
Carbon Sources ◽  
Sclerotium Rolfsii ◽  
Wild Type ◽  
Gliocladium Virens ◽  
Rhizosphere Competence ◽  
Filter Paper Cellulase ◽  
Type Strains

Aqueous suspensions of conidia of Gliocladium virens strains Gl-3 and Gl-21 were exposed to both ultraviolet radiation and ethyl methanesulfonate. Two mutants of Gl-3 and three of Gl-21 were selected for tolerance to benomyl at 10 μg∙mL−1, as indicated by growth and conidial germination on benomyl-amended potato dextrose agar. The mutants differed considerably from their respective wild-type strains in appearance, growth habit, sporulation, carbon-source utilization, and enzyme activity profiles. Of 10 carbon sources tested, cellobiose, xylose, and xylan were the best for growth, galactose and glucose were intermediate, and arabinose, ribose, and rhamnose were poor sources of carbon. The wild-type strains and the mutants did not utilize cellulose as the sole carbon source for growth. Two benomyl-tolerant mutants of Gl-3 produced less cellulase (β-1,4-glucosidase, carboxymethylcellulase, filter-paper cellulase) than Gl-3. In contrast, mutants of Gl-21 produced more cellulase than the wild-type strain. Only Gl-3 provided control of blight on snapbean caused by Sclerotium rolfsii. Wild-type strain Gl-21 and all mutants from both strains were ineffective biocontrol agents. Key words: Gliocladium, benomyl tolerance, Sclerotium, rhizosphere competence.

scholarly journals NUCLEAR MUTATION INCREASES STREPTOMYCIN AND SPECTINOMYCIN SENSITIVITY IN CHLAMYDOMONAS

Genetics ◽  
1978 ◽  
Vol 88 (4) ◽  
pp. 643-650
Author(s):  
Robert W Lee ◽  
Jan A Sapp
Keyword(s):  
Large Subunit ◽  
Small Subunit ◽  
Wild Type ◽  
Resistance Mutations ◽  
Erythromycin Resistance ◽  
Spectinomycin Resistance ◽  
Nuclear Mutation ◽  
Resistant Strains ◽  
Nuclear Locus ◽  
Type Strains

ABSTRACT A spontaneously arising nuclear mutation, ss-1, has been identified in Chlamydomonas reinhardtii that decreases both streptomycin and spectinomycin resistance levels about 10-fold after its introduction into all wild-type, streptomycin-resistant and spectinomycin-resistant strains examined. The mutations for resistance map to nuclear and uniparentally inherited (chloroplast) loci. In contrast, no modification of erythromycin resistance was detected after introducing ss-1 into wild-type strains or into strains carrying nuclear or uniparentally inherited erythromycin-resistance mutations. We suggest that ss-1 affects the small subunit of the chloroplast ribosome because others have shown that streptomycin and spectinomycin resistance in C. reinhardtii are associated with this subunit, whereas erythromycin resistance is associated with the large subunit. ss-1 shows no linkage with the nuclear locus for streptomycin resistance.

scholarly journals Essential Physiological Differences Characterize Short- and Long-Lived Strains of Drosophila melanogaster

2018 ◽  
Vol 74 (12) ◽  
pp. 1835-1843 ◽  
Author(s):  
Nina Gubina ◽  
Alba Naudi ◽  
Rhoda Stefanatos ◽  
Mariona Jove ◽  
Filippo Scialo ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Life Span ◽  
Foraging Behavior ◽  
Animal Species ◽  
Environmental Changes ◽  
Mitochondrial Gene ◽  
Genetic Component ◽  
Wild Type ◽  
Aging Research ◽  
Type Strains

Abstract Aging is a multifactorial process which affects all animals. Aging as a result of damage accumulation is the most accepted explanation but the proximal causes remain to be elucidated. There is also evidence indicating that aging has an important genetic component. Animal species age at different rates and specific signaling pathways, such as insulin/insulin-like growth factor, can regulate life span of individuals within a species by reprogramming cells in response to environmental changes. Here, we use an unbiased approach to identify novel factors that regulate life span in Drosophila melanogaster. We compare the transcriptome and metabolome of two wild-type strains used widely in aging research: short-lived Dahomey and long-lived Oregon R flies. We found that Dahomey flies carry several traits associated with short-lived individuals and species such as increased lipoxidative stress, decreased mitochondrial gene expression, and increased Target of Rapamycin signaling. Dahomey flies also have upregulated octopamine signaling known to stimulate foraging behavior. Accordingly, we present evidence that increased foraging behavior, under laboratory conditions where nutrients are in excess increases damage generation and accelerates aging. In summary, we have identified several new pathways, which influence longevity highlighting the contribution and importance of the genetic component of aging.

scholarly journals Novel Gene Product of Thogoto Virus Segment 6 Codes for an Interferon Antagonist

2003 ◽  
Vol 77 (4) ◽  
pp. 2747-2752 ◽  
Author(s):  
Kathrin Hagmaier ◽  
Stephanie Jennings ◽  
Johanna Buse ◽  
Friedemann Weber ◽  
Georg Kochs
Keyword(s):  
Transcriptional Activation ◽  
Matrix Protein ◽  
Wild Type ◽  
Interferon Inducer ◽  
Double Stranded Rna ◽  
Unspliced Transcript ◽  
A Genome ◽  
The Matrix ◽  
Alpha Beta ◽  
Type Strains

ABSTRACT Thogoto virus (THOV) is a tick-transmitted orthomyxovirus with a genome of six negative-stranded RNA segments. The sixth segment encodes two different transcripts: a spliced transcript that is translated into the matrix protein (M) and an unspliced transcript. Here, we report that the unspliced transcript encodes an elongated form of M named ML. A THOV isolate deficient in ML expression was an efficient interferon inducer, whereas ML-expressing wild-type strains were poor interferon inducers. These results were confirmed with recombinant THOVs rescued from cDNAs. Expression of ML efficiently suppressed activation of the beta interferon promoter by double-stranded RNA. These results indicate that ML is an accessory protein that functions as a potent interferon antagonist by blocking transcriptional activation of alpha/beta interferons.

scholarly journals Roles of Phosphatidylethanolamine and of Its Several Biosynthetic Pathways inSaccharomyces cerevisiae

2001 ◽  
Vol 12 (4) ◽  
pp. 997-1007 ◽  
Author(s):  
Ruth Birner ◽  
Maria Bürgermeister ◽  
Roger Schneiter ◽  
Günther Daum
Keyword(s):  
Biochemical Analysis ◽  
Membrane Vesicle ◽  
Carbon Sources ◽  
Carboxypeptidase Y ◽  
Deletion Mutants ◽  
Wild Type ◽  
Inner Mitochondrial Membrane ◽  
Minimal Level ◽  
Delayed Maturation

Three different pathways lead to the synthesis of phosphatidylethanolamine (PtdEtn) in yeast, one of which is localized to the inner mitochondrial membrane. To study the contribution of each of these pathways, we constructed a series of deletion mutants in which different combinations of the pathways are blocked. Analysis of their growth phenotypes revealed that a minimal level of PtdEtn is essential for growth. On fermentable carbon sources such as glucose, endogenous ethanolaminephosphate provided by sphingolipid catabolism is sufficient to allow synthesis of the essential amount of PtdEtn through the cytidyldiphosphate (CDP)-ethanolamine pathway. On nonfermentable carbon sources, however, a higher level of PtdEtn is required for growth, and the amounts of PtdEtn produced through the CDP-ethanolamine pathway and by extramitochondrial phosphatidylserine decarboxylase 2 are not sufficient to maintain growth unless the action of the former pathway is enhanced by supplementing the growth medium with ethanolamine. Thus, in the absence of such supplementation, production of PtdEtn by mitochondrial phosphatidylserine decarboxylase 1 becomes essential. Inpsd1Δ strains or cho1Δ strains (defective in phosphatidylserine synthesis), which contain decreased amounts of PtdEtn, the growth rate on nonfermentable carbon sources correlates with the content of PtdEtn in mitochondria, suggesting that import of PtdEtn into this organelle becomes growth limiting. Although morphological and biochemical analysis revealed no obvious defects of PtdEtn-depleted mitochondria, the mutants exhibited an enhanced formation of respiration-deficient cells. Synthesis of glycosylphosphatidylinositol-anchored proteins is also impaired in PtdEtn-depleted cells, as demonstrated by delayed maturation of Gas1p. Carboxypeptidase Y and invertase, on the other hand, were processed with wild-type kinetics. Thus, PtdEtn depletion does not affect protein secretion in general, suggesting that high levels of nonbilayer-forming lipids such as PtdEtn are not essential for membrane vesicle fusion processes in vivo.

scholarly journals An Update on Mitochondrial Ribosome Biology: The Plant Mitoribosome in the Spotlight

Cells ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1562 ◽  
Author(s):  
Artur Tomal ◽  
Malgorzata Kwasniak-Owczarek ◽  
Hanna Janska
Keyword(s):  
Structural Information ◽  
Mitochondrial Gene ◽  
Protein Composition ◽  
Small Subunit ◽  
Mitochondrial Gene Expression ◽  
Mitochondrial Ribosomes ◽  
Composition And Structure ◽  
Mitochondrial Ribosome ◽  
Different Types ◽  
Convincing Data

Contrary to the widely held belief that mitochondrial ribosomes (mitoribosomes) are highly similar to bacterial ones, recent experimental evidence reveals that mitoribosomes do differ significantly from their bacterial counterparts. This review is focused on plant mitoribosomes, but we also highlight the most striking similarities and differences between the plant and non-plant mitoribosomes. An analysis of the composition and structure of mitoribosomes in trypanosomes, yeast, mammals and plants uncovers numerous organism-specific features. For the plant mitoribosome, the most striking feature is the enormous size of the small subunit compared to the large one. Apart from the new structural information, possible functional peculiarities of different types of mitoribosomes are also discussed. Studies suggest that the protein composition of mitoribosomes is dynamic, especially during development, giving rise to a heterogeneous populations of ribosomes fulfilling specific functions. Moreover, convincing data shows that mitoribosomes interact with components involved in diverse mitochondrial gene expression steps, forming large expressosome-like structures.

scholarly journals Interactions among three proteins that specifically activate translation of the mitochondrial COX3 mRNA in Saccharomyces cerevisiae.

1994 ◽  
Vol 14 (2) ◽  
pp. 1045-1053 ◽  
Author(s):  
N G Brown ◽  
M C Costanzo ◽  
T D Fox
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Membrane ◽  
Wild Type ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Mutation ◽  
Mitochondrial Ribosomes ◽  
Functional Interactions ◽  
Cold Sensitive ◽  
Two Hybrid ◽  
Missense Substitution

The PET54, PET122, and PET494 proteins, which are associated with the yeast inner mitochondrial membrane, specifically activate translation of the mitochondrially encoded COX3 mRNA. We used the two-hybrid system to test whether pairs of these proteins, when fused to either the GAL4 DNA-binding or transcriptional activating domain, can physically associate as measured by the expression of the GAL4-dependent reporter, lacZ. PET54 and PET122 interacted in this system, and an amino-terminally truncated PET494 fragment showed an interaction with PET54. We also detected functional interactions between PET54 and PET122 genetically: a pet54 missense substitution (Phe to Gly at position 244) that caused a severe respiratory defect was suppressed both by a missense substitution affecting PET122 (Gly to Val at position 211) and by overproduction of wild-type PET122. Both Gly and Ala, substituted at PET54 position 244, disrupted the two-hybrid interactions with PET122 and PET494. While Ala at PET54 position 244 caused only a modest respiratory phenotype alone, it caused a severe respiratory defect when combined with a cold-sensitive mitochondrial mutation affecting the COX3 mRNA 5' leader. This synthetic defect was suppressed by a missense substitution in PET122 and by overproduction of wild-type PET122, indicating functional interactions among PET54, PET122, and the mRNA. Taken together with previous work, these data suggest that a complex containing PET54, PET122, and PET494 mediates the interaction of the COX3 mRNA with mitochondrial ribosomes at the surface of the inner membrane.

scholarly journals Biochemical and functional analysis of the YME1 gene product, an ATP and zinc-dependent mitochondrial protease from S. cerevisiae.

1996 ◽  
Vol 7 (2) ◽  
pp. 307-317 ◽  
Author(s):  
E R Weber ◽  
T Hanekamp ◽  
P E Thorsness
Keyword(s):  
Cytochrome Oxidase ◽  
Carbon Sources ◽  
Temperature Sensitive ◽  
Active Site Residues ◽  
Inner Mitochondrial Membrane ◽  
Conserved Sequence ◽  
Mitochondrial Inner Membrane ◽  
The Matrix ◽  
Sequence Elements ◽  
Critical Residues

Inactivation of YME1 in yeast causes several distinct phenotypes: an increased rate of DNA escape from mitochondria, temperature-sensitive growth on nonfermentable carbon sources, extremely slow growth when mitochondrial DNA is completely absent from the cell, and altered morphology of the mitochondrial compartment. The protein encoded by YME1, Yme1p, contains two highly conserved sequence elements, one implicated in the binding and hydrolysis of ATP, and the second characteristic of active site residues found in neutral, zinc-dependent proteases. Both the putative ATPase and zinc-dependent protease elements are necessary for the function of Yme1p as genes having mutations in critical residues of either of these motifs are unable to suppress any of the phenotypes exhibited by yme1 deletion strains. Yme1p co-fractionates with proteins associated with the mitochondrial inner membrane, is tightly associated with this membrane, and is oriented with the bulk of the protein facing the matrix. Unassembled subunit II of cytochrome oxidase is stabilized in yme1 yeast strains. The data support a model in which Yme1p is an ATP and zinc-dependent protease associated with the matrix side of the inner mitochondrial membrane. Subunit II of cytochrome oxidase, when not assembled into a higher order complex, is a likely substrate of Yme1p.

scholarly journals Functional interactions among two yeast mitochondrial ribosomal proteins and an mRNA-specific translational activator.

Genetics ◽  
1991 ◽  
Vol 127 (2) ◽  
pp. 319-326
Author(s):  
P Haffter ◽  
T W McMullin ◽  
T D Fox
Keyword(s):  
Ribosomal Proteins ◽  
Mitochondrial Gene ◽  
Nuclear Gene ◽  
Small Subunit ◽  
Mitochondrial Ribosomes ◽  
Gene Coding ◽  
Allele Specific ◽  
Carboxyl Terminal ◽  
Translational Activator ◽  
Carboxy Terminal

Abstract Expression of the Saccharomyces cerevisiae mitochondrial gene coding cytochrome c oxidase subunit III is specifically activated at the level of translation by at least three nuclear genes, PET122, PET494 and PET54. We have shown previously that carboxy-terminal deletions of PET122 are allele-specifically suppressed by mutations in an unlinked nuclear gene, termed PET123, that encodes a small subunit ribosomal protein. Here we describe additional pet122 suppressors generated by mutations in a second gene which we show to be the previously identified nuclear gene MRP1. Like PET123, MRP1 encodes a component of the small subunit of mitochondrial ribosomes. Our mrp1 mutations are allele-specific suppressors of carboxyl-terminal truncations of the PET122 protein and do not bypass the requirement for residual function of PET122. None of our mrp1 mutations has an intrinsic phenotype in an otherwise wild-type background. However, some of the mrp1 mutations cause a non-conditional respiratory-defective phenotype in combination with certain pet123 alleles. This synthetic defective phenotype suggests that the ribosomal proteins PET123 and MRP1 interact functionally with each other. The fact that they can both mutate to suppress certain alleles of the mRNA-specific translational activator PET122 strongly suggests that the PET122 protein promotes translation of the coxIII mRNA via an interaction with the small subunit of mitochondrial ribosomes.

scholarly journals Glucose and glucose 6-phosphate as carbon sources in extra- and intracellular growth of enteroinvasive Escherichia coli and Salmonella enterica

Microbiology ◽  
2010 ◽  
Vol 156 (4) ◽  
pp. 1176-1187 ◽  
Author(s):  
Andreas Götz ◽  
Werner Goebel
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Carbon Sources ◽  
Enteric Bacteria ◽  
Wild Type ◽  
Intracellular Replication ◽  
Inhibition Of Growth ◽  
Serovar Typhimurium ◽  
Type Strains

To study the role of carbohydrates, in particular glucose, glucose 6-phosphate and mannose, as carbon substrates for extra- and intracellular replication of facultative intracellular enteric bacteria, mutants of two enteroinvasive Escherichia coli (EIEC) strains and a Salmonella enterica serovar Typhimurium isolate were constructed that were defective in the uptake of glucose and mannose (ΔptsG, manXYZ), glucose 6-phosphate (ΔuhpT) or all three carbohydrates (ΔptsG, manXYZ, uhpT). The ability of these mutants to grow in RPMI medium containing the respective carbohydrates and in Caco-2 cells was compared with that of the corresponding wild-type strains. In the three strains, deletions of ptsG, manXYZ or uhpT resulted in considerably different levels of inhibition of growth in vitro in the presence of glucose, mannose and glucose 6-phosphate, respectively, but hardly reduced their capability for intracellular replication in Caco-2 cells. Even the triple mutants ΔptsG, manXYZ, uhpT of the three enterobacterial strains were still able to replicate in Caco-2 cells, albeit at strain-specific lower rates than the corresponding wild-type strains.

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