SEARCH · PubMed Health

Results for “Genes, Essential”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources

PubMed2006

Yeast autonomous linear plasmid pGKL2: ORF9 is an actively transcribed essential gene with multiple transcription start points.

A pair of linear plasmids, pGKL1 (8.9 kb) and pGKL2 (13.4 kb), resides in the cytoplasm of Kluyveromyces lactis killer strains. The smaller element, actually conferring the killer phenotype, strictly depends on the larger autonomous pGKL2. Here, we have examined the previously uncharacterized pGKL2 open reading frame (ORF)9 (1.34 kb). Northern analysis of a killer plasmid carrying Saccharomyces cerevisiae strain applying an ORF9-specific probe revealed a single transcript closely matching the size of the ORF9 coding region. Multiple transcriptional start points, determined by primer extension analysis, are located 16 nt downstream of a conserved sequence element regarded as the cytoplasmic promoter. In vivo disruption of pGKL2/ORF9 using the cytoplasmically expressible marker-gene LEU2* resulted in the establishment of a three-plasmid system composed of the native cytoplasmic elements pGKL1/2 and a hybrid of the latter, which only remained stable under selective conditions. The native pGKL2, however, did not segregate during prolonged subcultivations, proving an essential function of ORF9 for plasmid maintenance.

Base Sequence↗

PubMed1984

Yeast DNA topoisomerase II is encoded by a single-copy, essential gene.

The gene TOP2 encoding yeast topoisomerase II has been cloned by immunological screening of a yeast genomic library constructed in the phage lambda expression vector, lambda gt11. The ends of the message encoded by the cloned DNA fragment were delimited by the Berk and Sharp procedure (S1 nuclease mapping) for the 5' end and mapping of the polyA tail portion of a cDNA fragment for the 3' end. The predicted size of the message agrees with the length of the message as determined by Northern blot hybridization analysis. The identity of the gene was confirmed by expressing the gene in E. coli from the E. coli promoter lac UV5 to give catalytically active yeast DNA topoisomerase II. Disruption of one copy of the gene in a diploid yeast creates a recessive lethal mutation, indicating that the single DNA topoisomerase II gene of yeast has an essential function.

Base Sequence↗

PubMed1998

ARH1 of Saccharomyces cerevisiae: a new essential gene that codes for a protein homologous to the human adrenodoxin reductase.

A yeast gene was found in which the derived protein sequence has similarity to human and bovine adrenodoxin reductase (Nobrega, F. G., Nobrega, M. P. and Tzagoloff, A. (1992). EMBO J. 11, 3821-3829; Lacour, T. and Dumas, B. (1996). Gene 174, 289 292), an enzyme in the mitochondrial electron transfer chain that catalyses in mammals the conversion of cholesterol into pregnenolone, the first step in the synthesis of all steroid hormones. It was named ARH1 (Adrenodoxin Reductase Homologue 1) and here we show that it is essential. Rescue was possible by the yeast gene, but failed with the human gene. Supplementation was tried without success with various sterols, ruling out its involvement in the biosynthesis of ergosterol. Immunodetection with a specific polyclonal antibody located the gene product in the mitochondrial fraction. Consequently ARH1p joins the small group of gene products that affect essential functions carried out by the organelle and not linked to oxidative phosphorylation.

Amino Acid Sequence↗

PubMed1987

Yeast DNA polymerase--DNA primase complex; cloning of PRI 1, a single essential gene related to DNA primase activity.

The immunopurified yeast DNA polymerase--DNA primase complex is constituted by DNA polymerase I polypeptides and by three other protein species, called p74, p58 and p48, which we show to be immunologically unrelated. The gene encoding the p48 polypeptide has been identified by immunological screening of a lambda gt11 yeast genomic DNA library. Antiserum specific for p48 inhibits DNA primase, and immunoreactive, inhibitory antibodies are affinity-purified by the clone-encoded protein, thus relating the p48 polypeptide to DNA primase activity. The entire gene has been cloned, and the 1.45-kb p48 mRNA is overproduced in cells containing the gene in high copy number. Gene disruption and Southern hybridization experiments demonstrate that the p48 protein is encoded by a single gene and it performs an essential function.

Cloning, Molecular↗

PubMed1992

Cloning and characterization of rad21 an essential gene of Schizosaccharomyces pombe involved in DNA double-strand-break repair.

Analysis of the Schizosaccharomyces pombe chromosomes by pulsed field gel electrophoresis showed that the fission yeast has a very efficient DNA double-strand-break (dsb) repair system, which properly restores the three chromosomes after they are degraded by gamma-irradiation. The radiation-sensitive mutant rad21-45 is deficient in this repair pathway but is capable of cell-cycle arrest in G2 following DNA damage. We cloned the rad21 gene by complementing the radiation sensitivity of the rad21-45 mutant. The plasmid-borne gene completely reestablished the DNA dsb repair pathway. The rad21 gene was localized to chromosome III by hybridization. The transcript is 2.5 kb long and expressed at a moderate level. The 1884-bp open reading frame encodes a 628 amino acid, very acidic peptide with a calculated molecular mass of 67,854 D. The rad21 gene shows no significant homology to other known nucleotide or peptide sequences. The inability of the mutant to perform efficient DNA repair is caused by a single base substitution, which changes wild-type isoleucine67 into threonine in the mutant. Deletion of the genomic rad21 gene showed that it is essential for mitotic growth of S.pombe.

Amino Acid Sequence↗

PubMed1998

Characterization of the galU gene of Streptococcus pneumoniae encoding a uridine diphosphoglucose pyrophosphorylase: a gene essential for capsular polysaccharide biosynthesis.

The galU gene of Streptococcus pneumoniae has been cloned and sequenced. Escherichia coli cells harboring the recombinant plasmid pMMG2 (galU) overproduced a protein that has been shown to correspond to a uridine 5'-triphosphate:glucose-1-phosphate uridylyltransferase (uridine diphosphoglucose [UDP-Glc] pyrophosphorylase) responsible for the synthesis of UDP-Glc, a key compound in the biosynthesis of polysaccharides. A gene very similar to the S. pneumoniae galU has been found in a partial nucleotide sequence of the Streptococcus pyogenes genome. Knockout galU mutants of type 1 pneumococci are unable to synthesize a detectable capsule. An identical result was found in type 3 S. pneumoniae cells in spite of the fact that these bacteria contain a type-specific gene (cap3C) that also encodes a UDP-Glc pyrophosphorylase. Since eukaryotic UDP-Glc pyrophosphorylases appear to be completely unrelated to their prokaryotic counterparts, we postulate that GalU may be an appropriate target for the search of new drugs to control the pathogenicity of bacteria like pneumococcus and S. pyogenes.

Amino Acid Sequence↗

PubMed1998

Nup154, a new Drosophila gene essential for male and female gametogenesis is related to the nup155 vertebrate nucleoporin gene.

The Nup154 gene of Drosophila encodes a protein showing similarity with known nucleoporins: rat Nup155 and yeast Nup170 and Nup157. Hypomorphic mutant alleles of Nup154 affected female and male fertility, allowing investigation of the gene function in various steps of oogenesis and spermatogenesis. Nup154 was required in testes for cyst formation, control of spermatocyte proliferation and meiotic progression. In ovaries, Nup154 was essential for egg chamber development and oocyte growth. In both the male and female germ line, as well as in several other cell types, the Nup154 protein was detected at the nuclear membrane, but was also present inside the nucleus. Intranuclear localization has not previously been described for rat Nup155 or yeast Nup170 and Nup157. In mutant egg chambers the Nup154 protein accumulated in the cytoplasm, while it was only barely detected at the nuclear envelopes. FG repeats containing nucleoporins detected with mAb414 antibody were also mislocalized to a certain extent in Nup154 mutant alleles. This suggests that Nup154 could be required for localizing other nucleoporins within the nuclear pore complex, as previously demonstrated for the yeast Nup170. On the other hand, no evident defects in lamin localization were observed, indicating that Nup155 mutations did not affect the overall integrity of the nuclear envelope. However, ultrastructural analyses revealed that in mutant cells the morphology of the nuclear envelope was altered near the nuclear pore complexes. Finally, the multiplicity of phenotypes observed in Nup154 mutant alleles suggests that this gene plays a crucial role in cell physiology.

Amino Acid Sequence↗

PubMed1998

A mutation in NPS1/STH1, an essential gene encoding a component of a novel chromatin-remodeling complex RSC, alters the chromatin structure of Saccharomyces cerevisiae centromeres.

The NPS1/STH1 gene encodes a nuclear protein essential for the progression of G2/M phase in Saccharomyces cerevisiae . Nps1p shares homology to Snf2/Swi2p, a subunit of a protein complex known as the SNF/SWI complex. Recently, Nps1p was found to be a component of a protein complex termed RSC (3) essential for mitotic growth, whereas its function is unknown. We isolated a temperature-sensitive mutant allele of NPS1 , nps1-105, and found that the mutation increases the sensitivity to thiabendazole (TBZ). At the restrictive temperature, nps1-105 arrested at the G2/M phase in MAD1-dependent manner and missegregated the mini-chromosome with higher frequency than the wild type cells. The nuclease digestion of the chromatin of the mutant cells revealed that the mutation causes the alteration of the chromatin structure around centromeres at the restrictive temperature. The results suggested that, in the nps1-105 mutant, impaired chromatin structure surrounding centromeres may lead to an impairment of kinetochore function and the cells arrest at G2/M phase through the spindle-assembly checkpoint system.

Cell Cycle Proteins↗

PubMed1989

Farnesyl diphosphate synthetase. Molecular cloning, sequence, and expression of an essential gene from Saccharomyces cerevisiae.

Farnesyl diphosphate (FPP) synthetase is a key enzyme in isoprenoid biosynthesis which supplies C15 precursors for several classes of essential metabolites including sterols, dolichols, and ubiquinones. The structural gene for FPP synthetase was isolated on a 4.5-kilobase EcoRI genomic restriction fragment from the yeast Saccharomyces cerevisiae. The clone encodes a 40,483-dalton polypeptide of 342 amino acids with a high degree of similarity to the protein encoded by a putative rat liver clone of FPP synthetase (Clarke, C. F., Tanaka, R. D., Svenson, K., Wamsley, M., Fogelman, A. M., and Edwards, P. A. (1987) Mol. Cell Biol. 7, 3138-3146) and to an active site protein fragment from avian liver FPP synthetase (Brems, D. N., Bruenger, E., and Rilling, H. C. (1981) Biochemistry 20, 3711-3718). When cloned into the yeast shuttle vector YRp17, the 4.5-kilobase EcoRI fragment directed a 2-3-fold over-expression of FPP synthetase activity in transformed yeast cells. The levels of expression were independent of culture growth phase and orientation of the insert, indicative of a functional promoter in the clone. Disruption of the FPP synthetase gene from a diploid yeast strain, followed by dissection and analysis of tetrads, demonstrates that the gene is an essential, single copy number gene in yeast. The gene for FPP synthetase resides on chromosome XI as judged from Southern blots of separated yeast chromosomes.

Amino Acid Sequence↗

PubMed1996

Molecular analysis of UFE1, a Saccharomyces cerevisiae gene essential for spore formation and vegetative growth.

The UFE1 gene of Saccharomyces cerevisiae was cloned, sequenced and characterized. The coding region of UFE1 is separated from the TMP1 gene on chromosome XV by 624 bp. Gene-disruption experiments demonstrated that UFE1 is essential for both the germination of ascospores and for vegetative growth. Translation of the UFE1 coding region generates a protein with significant similarity to cytokeratin and to the coiled-coil region of SED5, USO1 and restin, suggesting that it is involved in the secretory pathway and may also be related to intermediate filament-associated proteins.

Amino Acid Sequence↗

PubMed1986

Survival of UV-irradiated mammalian cells correlates with efficient DNA repair in an essential gene.

The survival of UV-irradiated mammalian cells is not necessarily correlated with their overall capacity to carry out DNA repair. Human cells typically remove 80% of the pyrimidine dimers produced by a UV dose of 5 J/m2 within 24 hr. In contrast, a Chinese hamster ovary (CHO) cell line survives UV irradiation equally well while removing only 15% of the dimers. Using a newly developed technique to measure dimer frequencies in single-copy specific sequences, we find that the CHO cells remove 70% of the dimers from the essential dihydrofolate reductase (DHFR) gene but only 20% from sequences located 30 kilobases or more upstream from the 5' end of the gene in a 24-hr period. Repair-deficient human cells from xeroderma pigmentosum complementation group C (XPC) are similar to the CHO cells in overall repair levels, but they are extremely sensitive to killing by UV irradiation. In the XPC cells, we find little or no repair in the DHFR gene; in contrast, in normal human fibroblasts and epidermal keratinocytes, greater than 80% of the dimers induced in the gene by 20 J/m2 are removed in 24 hr. Since the CHO and normal human cells exhibit similar UV resistance, much higher than that of XPC cells, our findings suggest a correlation between efficient repair of essential genes and resistance to DNA-damaging agents such as UV light.

Animals↗

PubMed1992

PTA1, an essential gene of Saccharomyces cerevisiae affecting pre-tRNA processing.

We have identified an essential Saccharomyces cerevisiae gene, PTA1, that affects pre-tRNA processing. PTA1 was initially defined by a UV-induced mutation, pta1-1, that causes the accumulation of all 10 end-trimmed, intron-containing pre-tRNAs and temperature-sensitive but osmotic-remedial growth. pta1-1 does not appear to be an allele of any other known gene affecting pre-tRNA processing. Extracts prepared from pta1-1 strains had normal pre-tRNA splicing endonuclease activity. pta1-1 was suppressed by the ochre suppressor tRNA gene SUP11, indicating that the pta1-1 mutation creates a termination codon within a protein reading frame. The PTA1 gene was isolated from a genomic library by complementation of the pta1-1 growth defect. Episome-borne PTA1 directs recombination to the pta1-1 locus. PTA1 has been mapped to the left arm of chromosome I near CDC24; the gene was sequenced and could encode a protein of 785 amino acids with a molecular weight of 88,417. No other protein sequences similar to that of the predicted PTA1 gene product have been identified within the EMBL or GenBank data base. Disruption of PTA1 near the carboxy terminus of the putative open reading frame was lethal. Possible functions of the PTA1 gene product are discussed.

Base Sequence↗

PubMed2006

sucAB and sucCD are mutually essential genes in Escherichia coli.

sucAB and sucCD of Escherichia coli encode enzymes that generate succinyl-CoA from 2-oxoglutarate and succinate, respectively. Their mutual essentiality was studied. sucAB and sucCD could be deleted individually, but not simultaneously. The mutual essentiality of sucAB and sucCD was further confirmed by the conditional expression of sucABCD, sucAB, and sucCD under the control of a P(BAD) in E. coli MG1655, E. coli MG1655 (DeltasucCD), and E. coli MG1655 (DeltasucAB), respectively. These strains grew well in Luria-Bertani medium containing 0.1% arabinose, but not in the absence of arabinose unless the medium was supplemented with succinyl-CoA. Our results indicate that either sucAB or sucCD is enough to produce succinyl-CoA that is essential for cell viability.

Acyl Coenzyme A↗

PubMed2001

Drosophila CAPS is an essential gene that regulates dense-core vesicle release and synaptic vesicle fusion.

Calcium-activated protein for secretion (CAPS) is proposed to play an essential role in Ca2+-regulated dense-core vesicle exocytosis in vertebrate neuroendocrine cells. Here we report the cloning, mutation, and characterization of the Drosophila ortholog (dCAPS). Null dCAPS mutants display locomotory deficits and complete embryonic lethality. The mutant NMJ reveals a 50% loss in evoked glutamatergic transmission, and an accumulation of synaptic vesicles at active zones. Importantly, dCAPS mutants display a highly specific 3-fold accumulation of dense-core vesicles in synaptic terminals, which was not observed in mutants that completely arrest synaptic vesicle exocytosis. Targeted transgenic CAPS expression in identified motoneurons fails to rescue dCAPS neurotransmission defects, demonstrating a cell nonautonomous role in synaptic vesicle fusion. We conclude that dCAPS is required for dense-core vesicle release and that a dCAPS-dependent mechanism modulates synaptic vesicle release at glutamatergic synapses.

Amino Acid Sequence↗

PubMed1991

Replication factor-A from Saccharomyces cerevisiae is encoded by three essential genes coordinately expressed at S phase.

Replication factor-A (RF-A) is a three-subunit protein complex originally purified from human cells as an essential component for SV40 DNA replication in vitro. We have previously identified a functionally homologous three-subunit protein complex from the yeast Saccharomyces cerevisiae. Here we report the cloning and characterization of the genes encoding RF-A from S. cerevisiae. Each of the three subunits is encoded by a single essential gene. Cells carrying null mutations in any of the three genes arrest as budded and multiply budded cells. All three genes are expressed in a cell-cycle-dependent manner; the mRNA for each subunit peaks at the G1/S-phase boundary. A comparison of protein sequences indicates that the human p34 subunit is 29% identical to the corresponding RFA2 gene product. However, expression of the human protein fails to rescue the rfa2::TRP1 disruption.

Amino Acid Sequence↗

PubMed1989

Maize streak virus genes essential for systemic spread and symptom development.

The entire genome of single component geminiviruses such as maize streak virus (MSV) consists of a single-stranded circular DNA of ~2.7 kb. Although this size is sufficient to encode only three average sized proteins, the virus is capable of causing severe disease of many monocots with symptoms of chlorosis and stunting. We have identified viral gene functions essential for systemic spread and symptom development during MSV infection. Deletions and gene replacement mutants were created by site-directed mutagenesis and insertion between flanking MSV or reporter gene sequences contained in Agrobacterium T-DNA derived vectors. Following Agrobacterium-mediated inoculation of maize seedlings, the mutated MSV DNAs were excised from these binary vectors by homologous recombination within the flanking sequences. Our analyses show that the capsid gene of MSV, while not required for replication, is essential for systemic spread and subsequent disease development. The ;+' strand open reading frame (ORF) located immediately upstream from the capsid ORF and predicted to encode a 10.9 kd protein was also found to be dispensable for replication but essential for systemic spread. By this analysis, MSV sequences that support autonomous replication were localized to a 1.7 kb segment containing the two viral intergenic regions and two overlapping complementary ;-' strand ORFs. Despite the inability of the gene replacement mutants to spread systemically, both inoculated and newly developed leaves displayed chlorotic patterns similar to the phenotype observed in certain developmental mutants of maize. The similarity of the MSV mutant phenotype to these developmental mutants is discussed.

Journal Article↗

PubMed1986

Normal yeast tRNA(CAGGln) can suppress amber codons and is encoded by an essential gene.

We have isolated a gene that can encode yeast tRNA(CAGGln). When present on a multicopy plasmid, this gene suppresses the phenotype of a number of amber mutants, but has no effect on the ocher mutants tested. We therefore conclude that the anticodon CUG in tRNA(CAGGln) can decode the amber codon UAG by G-U mispairing, possibly by wobble base-pairing in the first codon position. This represents the second example we have observed in this laboratory of nonsense suppression in yeast by natural tRNA(Gln), involving G-U mispairing in the first codon position. Replacing the genomic copy of the cloned gene with a disrupted tRNA gene results in recessive lethality in heterozygous diploids and is lethal to haploid cells. This lethality can be rescued by transformation of cells with a single copy plasmid containing the tRNA(CAGGln) gene. Thus, the gene encoding tRNA(CAGGln) is apparently essential for viability in yeast, suggesting that it is normally present as a single copy gene.

Animals↗

PubMed2003

A mutation in the essential gene gmk (encoding guanlyate kinase) generates a requirement for adenine at low temperature in Salmonella enterica.

In Salmonella enterica serovar Typhimurium, gmk encodes guanylate kinase, an essential enzyme involved in the synthesis and salvage of guanine nucleotides. Here we report the isolation of a mutation in gmk that results in a nutritional requirement for adenine at low temperature. Comparisons of kinetic parameters from the wild-type and mutant Gmk enzymes revealed that the mutant enzyme had a more than 20-fold-higher Km for ATP than the wild-type enzyme. The growth dependence of the mutant on temperature and/or adenine could not be explained as a direct result of this kinetic difference. We propose a model in which previously described regulatory effects of GMP are responsible for these phenotypes.

Adenine↗