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Cloning and characterization of four B-hordein genes from Tibetan hull-less barley (Hordeum vulgare subsp. vulgare).

Four B-hordein genes, designated BH1-BH4, were cloned using PCR amplification from two hull-less barley cultivars, ZQ7239 and ZQ148, collected from Tibet. The results of sequencing indicated that BH1-BH4 contained complete open reading frames (ORFs). Comparison of their predicted polypeptide sequences with the published sequences suggested that they all share the same basic protein structure. Phylogenetic analysis indicated that the deduced amino-acid sequences of BH1-BH4 genes were more closely related to B-hordeins from cultivated barley (Hordeum vulgare L.) than to any other prolamins from wild barley and Aegilops tauschii. Comparison of the coding regions of BH1-BH4 genes showed that BH1 had a lower sequence identity to other previously published B-hordeins than the other three B-hordeins obtained in this study. BH1 was then cloned in a bacterial expression vector based on bacteriophage T7 RNA polymerase. The resulting plasmid produced a 28.15 kDa protein in Escherichia coli. The potential value of B-hordein genes in grain quality improvement of hull-less barley has been discussed.

Cloning, Molecular↗

A novel Rieske iron-sulfur protein from the hyperthermophilic crenarchaeon Pyrobaculum aerophilum: sequencing of the gene, expression in E. coli and characterization of the protein.

The crenarchaeon Pyrobaculum aerophilum is with an optimal growth temperature of 100 degrees C one of the most thermophilic organisms known to possess an aerobic respiratory chain. The analysis of DNA sequences from the Pyrobaculum genome project lead to the identification of an open reading frame potentially coding for a Rieske iron-sulfur protein. The complete gene (named parR) was cloned and sequenced. The deduced amino acid sequence displays unusual amino acid exchanges and a so far unknown sequence insertion. The N-terminus shows similarities to bacterial signal sequences. Several forms of the gene were expressed in E. coli in order to verify the classification as a Rieske protein and to facilitate biophysical studies. Soluble, thermo-stable proteins with correctly inserted iron-sulfur clusters were expressed from two versions of the gene. The delta1-23 truncated holo-protein is redox active. It displays the typical spectroscopic properties of a Rieske protein. The redox potential was determined to be +215 mV at pH 6.5 and is pH dependent above pH 7.5 revealing the influence of two protonation equilibria with pKa values of 8.1 and 9.8. Phylogenetic analysis demonstrates that the parR protein clusters together with the two other available archaeal Rieske sequences from Sulfolobus on a separate branch of the phylogenetic tree apart from the proteins from thermophilic bacteria like Aquifex and Thermus.

Amino Acid Sequence↗

Construction and analysis of recombinant DNA for human chorionic somatomammotropin.

DNA complementary to mRNA coding for the human polypeptide hormone, chorionic somatomammotropin, has been purified by specific restriction endonuclease digestion and religation before cloning into bacterial plasmids. The primary structure of a major portion of this mRNA species is deduced from the nucleotide sequence of the recombinant DNA.

Base Sequence↗

Cloning and expression of a cDNA encoding human placental protein 11, a putative serine protease with diagnostic significance as a tumor marker.

The placental protein 11 (PP11) can act as a tumor marker because of its specific association with various forms of cancer. A lambda gt11 cDNA library prepared from human placenta was screened with a polyclonal anti-PP11 antiserum. Out of 10(6) independent clones, only one clone reacted with the anti-PP11 antiserum. The isolated cDNA coded only for the carboxy-terminal part of PP11 and was subsequently used to rescreen a lambda gt10 placental cDNA library. Two cDNA clones out of 10(6) screened were identified encoding the entire protein of 369 amino acids, including a typical hydrophobic signal sequence of 18 amino acids. Expression of the PP11 cDNA coding sequence in Escherichia coli resulted in the synthesis of a protein with the expected size which can be specifically immunoprecipitated with anti-PP11 antiserum. Fractionation experiments revealed that two forms of the protein are present in the bacterial cell: a higher-molecular-weight form of approximately 42 kD in the cytoplasm and a smaller-molecular-weight form of approximately 42 kD in the periplasm. This result indicates that PP11 can be synthesized in E. coli and is process by removal of the hydrophobic signal sequence. Both the placental and the processed recombinant PP11 protein exhibit a protease activity.

Amino Acid Sequence↗

The Epstein-Barr virus open reading frame BDLF3 codes for a 100-150 kDa glycoprotein.

The Epstein-Barr virus (EBV) open reading frame BDLF3 is predicted to code for a glycoprotein on the basis that it contains sequences with signal peptide and transdomain characteristics and nine potential N-linked glycosylation sites. No sequential or positional homologues of BDLF3 have been located in other herpesviruses. A bacterial glutathione S-transferase (GST)-BDLF3 fusion protein was used to demonstrate that over one-third of EBV-immune human sera tested recognized the fusion protein but not GST alone on Western blots. The fusion protein was used to raise polyclonal sera in rabbits. A BDLF3 recombinant baculovirus was constructed using the full-length BDLF3 sequence (AcBDLF3). Rabbit anti-fusion protein sera and some human EBV-immune sera recognized products of approximately 30 and 55 kDa from AcBDLF3-infected insect cells by Western blotting. A peptide representing the carboxy-terminal amino acids 215-234 of the BDLF3 sequence was used to raise anti-peptide sera in rabbits. Anti-peptide serum detected a product by indirect immunofluorescence in acetone-fixed EBV-infected B cells from all cell lines tested. A diffuse band with a molecular mass of 100-150 kDa was detected by Western blot in B95-8 cell lysates, partially purified B95-8 virus and B95-8-infected cell membranes after probing with anti-BDLF3 peptide serum. This product was shown to be glycosylated after enzymatic deglycosylation of a B95-8 virus preparation using neuraminidase, O-glycosidase or N-glycosidase F. The BDLF3 protein products have no known function.

Animals↗

Structure of sea-urchin arylsulfatase gene.

The gene encoding arylsulfatase (Ars; EC 3.1.6.1) as well as two Ars pseudogenes were isolated from sea urchin genomic libraries. The Ars gene was 20-kbp long and contained six exons interrupted by five introns. Four polypyrimidine repetitive sequences were dispersed in its upstream-flanking region. Comparison of the amino acid sequence of sea-urchin arylsulfatase with those of human sterol sulfatase, human arylsulfatase A and bacterial arylsulfatase revealed that they have two similar sequences in common. The position of the transcription-start site of the Ars gene was determined to be approximately 40-bp upstream from the 5' end of the protein-coding region, and the nucleotide sequence of the 5'-flanking region was determined up to 3.3 kbp upstream from the transcription start point. Putative TATAA box and CCAAT consensus sequences were located at positions -28 and -82, respectively. A highly conserved hexamer motif, CTCTTT, localized near the transcription-start site of the sea-urchin Ars gene, was also detected in similar regions of other sea urchin genes such as CyIIIa, Spec 1, Spec 2a, Spec 2c, Spec 2d, and SM50, but not in the histone genes.

Amino Acid Sequence↗

Detection of Eikenella corrodens and Actinobacillus actinomycetemcomitans by use of the polymerase chain reaction (PCR) in vitro and in subgingival plaque.

The purpose of the present investigation was to identify 2 putative periodontal pathogens: Eikenella corrodens and Actinobacillus actinomycetemcomitans by polymerase chain reaction (PCR) in vitro and in subgingival plaque. On the basis of published sequences coding for 16S rRNA two primer pairs were designed which amplify a 410 bp sequence from E. corrodens DNA and a 547 bp fragment from A. actinomycetemcomitans DNA, respectively. As few as 50 cells could be detected from pure bacterial cultures. Each of the two primer pairs was found to be specific in that it did not give any amplification product neither with cell lysates from the respective alternative bacterium nor with lysates obtained from other putative periodontal pathogens and other bacteria. The PCR method developed turned out to be a simple, rapid and reliable diagnostic tool for the detection of the target microorganisms in clinical samples.

Aggregatibacter actinomycetemcomitans↗

fhuC and fhuD genes for iron (III)-ferrichrome transport into Escherichia coli K-12.

The nucleotide sequence for a 1,900-base-pair region of the Escherichia coli chromosome that includes the genes fhuC and fhuD was determined. Within this sequence are two open reading frames: nucleotides 127 to 921 and nucleotides 924 to 1811. These coding regions specify a FhuC protein with an Mr of 28,423 and a mature FhuD protein with an Mr of 29,610. The deduced amino acid sequence of FhuC shows extensive homology with those of components of some bacterial transport systems which are peripheral proteins of the cytoplasmic membrane. Because the FhuD protein contains a typical signal sequence of 30 amino acids at the amino terminus and displays characteristics of a soluble protein, it may be exported into the periplasm.

Amino Acid Sequence↗

Novel trimeric adenylate kinase from an extremely thermoacidophilic archaeon, Sulfolobus solfataricus: molecular cloning, nucleotide sequencing, expression in Escherichia coli, and characterization of the recombinant enzyme.

A gene coding for adenylate kinase was cloned from an extremely thermoacidophilic archaeon Sulfolobus solfataricus. The open reading frame of the sequenced gene consisted of 585 nucleotides coding for a polypeptide of 195 amino acid residues with a calculated molecular weight of 21,325. Although the S. solfataricus adenylate kinase, which belonged to the small variants of the adenylate kinase family, had low sequence identities with bacterial and eukaryotic enzymes, a functionally important glycine-rich region and also two invariant arginine residues were conserved in the sequence of the S. solfataricus enzyme. The recombinant enzyme, overexpressed in Escherichia coli and purified to homogeneity, had high affinity for AMP and high thermal stability, comparable to the extremely thermostable enzyme from a similar archaeon, S. acidocaldarius. Furthermore, gel filtration and sedimentation analyses showed that the S. solfataricus adenylate kinase was a homotrimer in solution, which is a novel subunit structure for nucleoside monophosphate kinases.

Adenylate Kinase↗

Studies on the holoenzyme biogenesis of the spinach ferredoxin-NADP+ reductase.

An expression plasmid, pPreFNR, in which the DNA sequence coding for the spinach ferredoxin-NADP+ reductase precursor was under the control of prokaryotic transcription and translation initiation signals has been constructed. The plasmid directed the synthesis in Escherichia coli of a 43-kDa immunoreactive polypeptide which could be identified with the reductase preprotein. Analyses of bacterial extracts showed that the precursor was unstable and devoid of catalytic activities, suggesting that the presence of the transit peptide would not allow the assembly in E. coli of an active preholoenzyme. Furthermore, the reductase precursor was found to undergo a processing in E. coli. The proteolysed form, which retained 13 of the 55 residues of the transit peptide, was active, suggesting that removal of the first 42 residues of the presequence enabled the protein to properly fold and to bind the FAD prosthetic group in the bacterial host, as it was previously shown in the case of the mature form of the spinach reductase.

Amino Acid Sequence↗

Genomic organization and chromosomal mapping of ELKS, a gene rearranged in a papillary thyroid carcinoma.

We recently isolated a novel cDNA, designated ELKS, that was fused to RET cDNA in a papillary thyroid carcinoma. Its encoded polypeptide sequence was rich in glutamic acid (E), leucine (L), lysine (K), and serine (S), and was characterized by the presence of nine alpha-helical coiled-coil domains consisting of periodic heptad repeats. We have now cloned the entire structure of the human ELKS gene from within a 700-kb genomic region represented by overlapping bacteriophage P1-derived artificial chromosome (PAC) and bacterial artificial chromosome (BAC) clones, and localized it to chromosomal band 12p13.3 by fluorescence in situ hybridization. The gene is approximately 500 kb long, with 19 exons and 18 introns; the transcription initiation site within exon 1 is separate from the initiation codon (in exon 2). Analysis of the exon/intron structure revealed that introns interrupt the coding sequence in such a way that many functional segments of the protein are encoded by distinct exons. Exon 1 encodes the 5' non-coding region; exons 2, 3, 6, 7, 8, 9, 11, 14, and 15 encode the nine coiled-coil domains. Exons 17-19 constitute the 3' non-coding region. Analysis of the region immediately upstream of exon 1 showed that it was extremely rich in G/C nucleotides and contained multiple Sp-1 and AP2 binding sequences. The ELKS-RET gene fusion rearrangement we had observed in a papillary thyroid carcinoma occurred between intron 10 of the ELKS gene and intron 11 of RET.

Adaptor Proteins, Signal Transducing↗

Identification of a new class of nitrogen fixation genes in Rhodobacter capsulatus: a putative membrane complex involved in electron transport to nitrogenase.

DNA sequence analysis of a 12236 bp fragment, which is located upstream of nifE in Rhodobacter capsulatus nif region A, revealed the presence of ten open reading frames. With the exception of fdxC and fdxN, which encode a plant-type and a bacterial-type ferredoxin, the deduced products of these coding regions exhibited no significant homology to known proteins. Analysis of defined insertion and deletion mutants demonstrated that six of these genes were required for nitrogen fixation. Therefore, we propose to call these genes rnfA, rnfB, rnfC, rnfD, rnfE and rnfF (for Rhodobacter nitrogen fixation). Secondary structure predictions suggested that the rnf genes encode four potential membrane proteins and two putative iron-sulphur proteins, which contain cysteine motifs (C-X2-C-X2-C-X3-C-P) typical for [4Fe--4S] proteins. Comparison of the in vivo and in vitro nitrogenase activities of fdxN and rnf mutants suggested that the products encoded by these genes are involved in electron transport to nitrogenase. In addition, these mutants were shown to contain significantly reduced amounts of nitrogenase. The hypothesis that this new class of nitrogen fixation genes encodes components of an electron transfer system to nitrogenase was corroborated by analysing the effect of metronidazole. Both the fdxN and rnf mutants had higher growth yields in the presence of metronidazole than the wild type, suggesting that these mutants contained lower amounts of reduced ferredoxins.

Amino Acid Sequence↗

Screening by polymerase chain reaction of Bacillus thuringiensis serotypes for the presence of cryV-like insecticidal protein genes and characterization of a cryV gene cloned from B. thuringiensis subsp. kurstaki.

Polymerase chain reaction screening using cryV-specific oligonucleotides, designed to amplify the 5' half of cryV-type genes, revealed the presence of such genes in 7 of 21 Bacillus thuringiensis serotypes examined. Restriction analysis and hybridization studies indicated that these putative genes fall into at least three subclasses. The nucleotide sequence of the cryV-type gene cloned from B. thuringiensis subsp. kurstaki DSIR732 revealed an open reading frame coding for a protein of 719 amino acids, and lysates of Escherichia coli cells expressing the 81.2-kDa CryV732 protein were toxic to Epiphyas postvittana (Lepidoptera: Tortricidae).

Bacillus thuringiensis↗

Diversity in coding tandem repeats in related Neisseria spp.

BACKGROUND: Tandem repeats contained within coding regions can mediate phase variation when the repeated units change the reading frame of the coding sequence in a copy number dependent manner. Coding tandem repeats are those which do not alter the reading frame with copy number, and the changes in copy number of these repeats may then potentially alter the function or antigenicity of the protein encoded. Three complete neisserial genomes were analyzed and compared to identify coding tandem repeats where the number of copies of the repeat will have some structural consequence for the protein. This is the first study to address coding tandem repeats that may affect protein structures using comparative genomics, combined with a population survey to investigate which show interstrain variability. RESULTS: A total of 28 genes were identified. Of these, 22 contain coding tandem repeats that vary in copy number between the three sequenced strains, three strain specific genes were included for investigation on the basis of having >90% identity between repeated units, and three genes with repeated elements of >250 bp were included although no length variations were seen in the genomes. Amplification, and sequencing of repeats showing altered copy number, of these 28 coding tandem repeat containing regions, from a set of largely unrelated strains, revealed further repeat length variation in several cases. CONCLUSION: Eighteen genes were identified which have variation in repeat copy number between strains of the same species, twelve of which show greater diversity in repeat copy number than is present in the sequenced genomes. In some cases, this may reflect a mechanism for the generation of antigenic variation, as previously described in other species. However, some of the genes identified encode proteins with cytoplasmic functions, including sugar metabolism, DNA repair, and protein production, in which repeat length variation may have other functions. Coding tandem repeats appear to represent a largely unexplored mechanism of generating diversity in the Neisseria spp.

Adhesins, Bacterial↗

Common evolutionary origin of the ilvGMEDA attenuation locus and tRNA(1Leu) in Escherichia coli.

Published sequences of transcripts from ilvGMEDA leader regions of several enteric bacteria were compared with published sequences of the tRNAs from Escherichia coli. The analyses revealed homology between the ilvGMEDA leader peptide-coding region and tRNA(1Leu) in E. coli, Salmonella typhimurium, and Klebsiella aerogenes, whereas homology was not present in Serratia marcescens and Edwardsiella tarda.

Biological Evolution↗