scholarly journals Genetic Localization and Molecular Characterization of the nonS Gene Required for Macrotetrolide Biosynthesis inStreptomyces griseus DSM40695

2000 ◽  
Vol 44 (7) ◽  
pp. 1809-1817 ◽  
Author(s):  
Wyatt C. Smith ◽  
Longkuan Xiang ◽  
Ben Shen
Keyword(s):  
Polyketide Synthase ◽  
Isotope Labeling ◽  
Streptomyces Griseus ◽  
Open Reading Frames ◽  
A Cell ◽  
Cyclic Polyethers ◽  
The Difference ◽  
Reading Frames

ABSTRACT The macrotetrolides are a family of cyclic polyethers derived from tetramerization, in a stereospecific fashion, of the enantiomeric nonactic acid (NA) and its homologs. Isotope labeling experiments established that NA is of polyketide origin, and biochemical investigations demonstrated that 2-methyl-6,8-dihydroxynon-2E-enoic acid can be converted into NA by a cell-free preparation from Streptomyces lividans that expresses nonS. These results lead to the hypothesis that macrotetrolide biosynthesis involves a pair of enantiospecific polyketide pathways. In this work, a 55-kb contiguous DNA region was cloned from Streptomyces griseus DSM40695, a 6.3-kb fragment of which was sequenced to reveal five open reading frames, including the previously reported nonR andnonS genes. Inactivation of nonS in vivo completely abolished macrotetrolide production. Complementation of thenonS mutant by the expression of nonS intrans fully restored its macrotetrolide production ability, with a distribution of individual macrotetrolides similar to that for the wild-type producer. In contrast, fermentation of thenonS mutant in the presence of exogenous (±)-NA resulted in the production of nonactin, monactin, and dinactin but not in the production of trinactin and tetranactin. These results prove the direct involvement of nonS in macrotetrolide biosynthesis. The difference in macrotetrolide production between in vivo complementation of the nonS mutant by the plasmid-borne nonSgene and fermentation of the nonS mutant in the presence of exogenously added (±)-NA suggests that NonS catalyzes the formation of (−)-NA and its homologs, supporting the existence of a pair of enantiospecific polyketide pathways for macrotetrolide biosynthesis inS. griseus. The latter should provide a model that can be used to study the mechanism by which polyketide synthase controls stereochemistry during polyketide biosynthesis.

scholarly journals Characterization of Endogenous Retroviruses in Sheep

2003 ◽  
Vol 77 (20) ◽  
pp. 11268-11273 ◽  
Author(s):  
Nikolai Klymiuk ◽  
Mathias Müller ◽  
Gottfried Brem ◽  
Bernhard Aigner
Keyword(s):  
Endogenous Retrovirus ◽  
Ovis Aries ◽  
Endogenous Retroviruses ◽  
Open Reading Frames ◽  
In Vivo Experiments ◽  
Pregnant Sheep ◽  
Reading Frames

ABSTRACT Endogenous retrovirus (ERV) sequences have been found in all mammals. In vitro and in vivo experiments revealed ERV activation and cross-species infection in several species. Sheep (Ovis aries) are used for various biotechnological purposes; however, they have not yet been comprehensively screened for ERV sequences. Therefore, the aim of the study was to classify the ERV sequences in the ovine genome (OERV) by analyzing the retroviral pro-pol sequences. Three OERV β families and nine OERV γ families were revealed. Novel open reading frames (ORF) in the amplified proviral fragment were found in one OERV β family and two OERV γ families. Hybrid OERV produced by putative recombination events were not detected. Quantitative analysis of the OERV sequences in the ovine genome revealed no relevant variations in the endogenous retroviral loads of different breeds. Expression analysis of different tissues from fetal and pregnant sheep detected mRNA from both gammaretrovirus families, showing ORF fragments. Thus, the release of retroviruses from sheep cells cannot be excluded.

scholarly journals Characterization of ssfR andssgA, Two Genes Involved in Sporulation ofStreptomyces griseus

2000 ◽  
Vol 182 (19) ◽  
pp. 5521-5529 ◽  
Author(s):  
Hao Jiang ◽  
Kathleen E. Kendrick
Keyword(s):  
Stop Codon ◽  
Streptomyces Griseus ◽  
Large Family ◽  
Resistant Mutant ◽  
Open Reading Frames ◽  
Dna Fragment ◽  
Morphological Differences ◽  
White Mutant ◽  
Reading Frames

ABSTRACT In the presence of cefoxitin, which inhibits septum formation during sporulation, Streptomyces griseus is unable to sporulate, retaining the sonication sensitivity of nonsporulating hyphae. Cefoxitin- and sonication-resistant mutant SKK2600 was isolated and showed many morphological differences from its parental strain. A 3.6-kb DNA fragment that complemented the mutations of SKK2600 contained two open reading frames (ORFs), either of which could complement SKK2600. One ORF, designated ssfR, encoded a protein containing a potential DNA-binding helix-turn-helix motif close to its N terminus. SsfR is similar to members of a large family of transcriptional regulators, particularly IclR of Escherichia coli. The second ORF was identified as ssgA, a previously described sporulation gene from S. griseus (S. Kawamoto and J. C. Ensign, Actinomycetology 9:136–151, 1995). A point mutation of C to T seven nucleotides upstream of the UGA stop codon of ssfR was responsible for the phenotype of isolated mutant strain SKK2600. Surprisingly, this mutation should not change the primary structure of SsfR. The ssfR andssgA disruption mutants were constructed and showed the “white” mutant phenotype, with some growth medium dependence. In addition, the ssfR null mutant sporulated ectopically in phosphate starvation medium.

scholarly journals Identification and Characterization of a Gene Cluster for Synthesis of the Polyketide Antibiotic 2,4-Diacetylphloroglucinol from Pseudomonas fluorescens Q2-87

1999 ◽  
Vol 181 (10) ◽  
pp. 3155-3163 ◽  
Author(s):  
M. Gita Bangera ◽  
Linda S. Thomashow
Keyword(s):  
Genomic Dna ◽  
Plant Pathogens ◽  
Polyketide Synthase ◽  
Open Reading Frames ◽  
Fungal Plant Pathogens ◽  
Repressor Proteins ◽  
Flanking Regions ◽  
Identification And Characterization ◽  
Reading Frames

The polyketide metabolite 2,4-diacetylphloroglucinol (2,4-DAPG) is produced by many strains of fluorescent Pseudomonas spp. with biocontrol activity against soilborne fungal plant pathogens. Genes required for 2,4-DAPG synthesis by P. fluorescensQ2-87 are encoded by a 6.5-kb fragment of genomic DNA that can transfer production of 2,4-DAPG to 2,4-DAPG-nonproducing recipientPseudomonas strains. In this study the nucleotide sequence was determined for the 6.5-kb fragment and flanking regions of genomic DNA from strain Q2-87. Six open reading frames were identified, four of which (phlACBD) comprise an operon that includes a set of three genes (phlACB) conserved between eubacteria and archaebacteria and a gene (phlD) encoding a polyketide synthase with homology to chalcone and stilbene synthases from plants. The biosynthetic operon is flanked on either side by phlEand phlF, which code respectively for putative efflux and regulatory (repressor) proteins. Expression in Escherichia coli of phlA, phlC, phlB, andphlD, individually or in combination, identified a novel polyketide biosynthetic pathway in which PhlD is responsible for the production of monoacetylphloroglucinol (MAPG). PhlA, PhlC, and PhlB are necessary to convert MAPG to 2,4-DAPG, and they also may function in the synthesis of MAPG.

Translational activation of GCN4 mRNA in a cell-free system is triggered by uncharged tRNAs

1990 ◽  
Vol 10 (8) ◽  
pp. 4375-4378
Author(s):  
G Krupitza ◽  
G Thireos
Keyword(s):  
Open Reading Frames ◽  
Yeast Cells ◽  
Free System ◽  
In Vitro System ◽  
A Cell ◽  
Translational Activation ◽  
Reading Frames ◽  
Small Open Reading Frames

Translation of GCN4 mRNA is activated when yeast cells are grown under conditions of amino acid limitation. In this study, we established the conditions through which translation of the GCN4 mRNA could be activated in a homologous in vitro system. This activation paralleled the in vivo situation: it required the small open reading frames located in the 5' untranslated region of the GCN4 mRNA, and it was coupled with reduced rates of 43S preinitiation complex formation. Translational derepression in vitro was triggered by uncharged tRNA molecules, demonstrating that deacylated tRNAs are more proximal signals for translational activation of the GCN4 mRNA.

scholarly journals Translational activation of GCN4 mRNA in a cell-free system is triggered by uncharged tRNAs.

1990 ◽  
Vol 10 (8) ◽  
pp. 4375-4378 ◽  
Author(s):  
G Krupitza ◽  
G Thireos
Keyword(s):  
Open Reading Frames ◽  
Yeast Cells ◽  
Free System ◽  
In Vitro System ◽  
A Cell ◽  
Translational Activation ◽  
Reading Frames ◽  
Small Open Reading Frames

Translation of GCN4 mRNA is activated when yeast cells are grown under conditions of amino acid limitation. In this study, we established the conditions through which translation of the GCN4 mRNA could be activated in a homologous in vitro system. This activation paralleled the in vivo situation: it required the small open reading frames located in the 5' untranslated region of the GCN4 mRNA, and it was coupled with reduced rates of 43S preinitiation complex formation. Translational derepression in vitro was triggered by uncharged tRNA molecules, demonstrating that deacylated tRNAs are more proximal signals for translational activation of the GCN4 mRNA.

scholarly journals Analysis of Early Promoters of theBacillus Bacteriophage GA-1

2001 ◽  
Vol 183 (23) ◽  
pp. 6965-6970 ◽  
Author(s):  
José A. Horcajadas ◽  
Wilfried J. J. Meijer ◽  
Fernando Rojo ◽  
Margarita Salas
Keyword(s):  
Bacillus Subtilis ◽  
In Vitro Transcription ◽  
Open Reading Frames ◽  
Early Infection ◽  
Infection Cycle ◽  
Reading Frames

ABSTRACT Bacteriophage GA-1, which infects Bacillus sp. strain G1R, is evolutionarily related to phage φ29, which infectsBacillus subtilis. We report the characterization of several GA-1 promoters located at either end of its linear genome. Some of them are unique for GA-1 and drive the expression of open reading frames that have no counterparts in the genome of φ29 or related phages. These unique promoters are active at early infection times and are repressed at late times. In vitro transcription reactions revealed that the purified GA-1-encoded protein p6 represses the activity of these promoters, although the amount of p6 required to repress transcription was different for each promoter. The level of protein p6 produced in vivo increases rapidly during the first stage of the infection cycle. The protein p6 concentration may serve to modulate the expression of these early promoters as infection proceeds.

scholarly journals Cloning and Characterization of a Gene Cluster for Hatomarubigin Biosynthesis in Streptomyces sp. Strain 2238-SVT4

2010 ◽  
Vol 76 (13) ◽  
pp. 4201-4206 ◽  
Author(s):  
Takashi Kawasaki ◽  
Reiko Hirashima ◽  
Tomoka Maruta ◽  
Haruka Sato ◽  
Ayumi Maeda ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Polyketide Synthase ◽  
Streptomyces Lividans ◽  
Open Reading Frames ◽  
Specific Primers ◽  
Streptomyces Sp ◽  
Dimeric Structure ◽  
Genes Expression ◽  
Reading Frames

ABSTRACT Streptomyces sp. strain 2238-SVT4 produces hatomarubigins A, B, C, and D, which belong to the angucycline family. Among them, hatomarubigin D has a unique dimeric structure with a methylene linkage. PCR using aromatase and cyclase gene-specific primers identified the hrb gene cluster for angucycline biosynthesis in Streptomyces sp. 2238-SVT4. The cluster consisted of 30 open reading frames, including those for the minimal polyketide synthase, ketoreductase, aromatase, cyclase, O-methyltransferase, oxidoreductase, and oxygenase genes. Expression of a part of the gene cluster containing hrbR1 to hrbX in Streptomyces lividans TK23 resulted in the production of hatomarubigins A, B, and C. Hatomarubigin D was obtained from the conversion of hatomarubigin C by a purified enzyme encoded by hrbY, among the remaining genes.

scholarly journals Characterization of the Pasteurella multocida hgbA Gene Encoding a Hemoglobin-Binding Protein

2002 ◽  
Vol 70 (11) ◽  
pp. 5955-5964 ◽  
Author(s):  
Montserrat Bosch ◽  
M. Elena Garrido ◽  
Montserrat Llagostera ◽  
Ana M. Pérez de Rozas ◽  
Ignacio Badiola ◽  
...  
Keyword(s):  
Pasteurella Multocida ◽  
Bacterial Pathogen ◽  
Open Reading Frames ◽  
Transcriptional Unit ◽  
Gene Encoding ◽  
Hemoglobin Binding ◽  
Reading Frames

ABSTRACT Reverse transcriptase PCR analyses have demonstrated that open reading frames (ORFs) PM0298, PM0299, and PM0300 of the animal pathogen Pasteurella multocida constitute a single transcriptional unit. By cloning and overexpression studies in Escherichia coli cells, the product of ORF PM0300 was shown to bind hemoglobin in vitro; this ORF was therefore designated hgbA. In vitro and in vivo quantitative assays demonstrated that the P. multocida hgbA mutant bound hemoglobin to the same extent as the wild-type strain, although the adsorption kinetics was slightly slower for the hgbA cells. In agreement with this, the virulence of P. multocida hgbA cells was not affected, suggesting that other functional hemoglobin receptor proteins must be present in this organism. On the other hand, P. multocida mutants defective in PM0298 and PM0299 could be isolated only when a plasmid containing an intact copy of the gene was present in the cells, suggesting that these genes are essential for the viability of this bacterial pathogen. By adapting the recombinase-based expression technology in vivo to P. multocida, we also demonstrated that the transcriptional PM0298-PM0299-hgbA unit is iron regulated and that its expression is triggered in the first 2 h following infection in a mouse model. Furthermore, hybridization experiments showed that the hgbA gene is widespread in P. multocida strains regardless of their serotype or the animal from which they were isolated.

MOLECULAR CHARACTERIZATION OF A NOVEL RAT PARVOVIRUS IN TAIWAN

2014 ◽  
Vol 40 (01) ◽  
pp. 11-19 ◽  
Author(s):  
Yi-Chun Liao ◽  
Ming-Hseng Wang ◽  
Cho-Hua Wan
Keyword(s):  
Molecular Characterization ◽  
Open Reading Frames ◽  
Infectious Agents ◽  
Sequence Comparisons ◽  
Laboratory Rats ◽  
Laboratory Rodents ◽  
Reading Frames

Rodent parvoviruses are among the most prevalent infectious agents in laboratory rodents and have been shown to interfere with in vivo and in vitro research. A newly recognized rat parvovirus (RPV) that is distinct from the prototypic RPV was recently identified in naturally infected laboratory rats in Taiwan. Nucleotide and amino acid sequence comparisons showed that this newly identified variant of RPV is most closely related to rat parvovirus type 1a (RPV-1a) and type 1b (RPV-1b) and is distinctly different from type UT (RPV/UT) and other rodent parvoviruses. This variant was designated rat parvovirus type National Taiwan University 1 (RPV-NTU1). Phylogenetic and sequence analyses revealed that RPV-NTU1 contains conserved open reading frames with an overall genome organization similar to known RPV-1. RPV-NTU1 is the second RPV-1 variant whose full-length molecular characterization has been performed.

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