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Cloning, sequencing, and expression of cscA invertase from Escherichia coli B-62.

We have isolated a 2.5-kb DNA fragment from plasmid pST5R7 encoding a sucrose utilization system from Escherichia coli B-62 which confers a sucrose-fermenting phenotype to transformed E. coli K-12 strains. DNA-sequence determination revealed one full-length open reading frame 98% identical to cscA, the sucrose-hydrolase (invertase) gene of the csc regulon from E. coli EC3132. Functional characterization indicates that high-level expression and limited periplasmic release of invertase is responsible for the sucrose-fermenting capacity of transformed E. coli K-12 strains carrying cscA.

Bacterial Proteins↗

[Structure of over lapping region of ICP18.5 and gB genes of type 1 bovine herpesvirus strain TK-A].

Nucleotide sequence of DNA fragment coding 3'-terminal of ICO 18.5 gene that overlaps the regulatory region and 5'-terminal of open reading frame of gB gene of bovine herpesvirus (BHV-1, subtype 1.3), strain TK-A, was determined. Comparative analysis of the sequence with the corresponding DNA regions of BHV-1, subtype 1.1, equine herpesviruses of the first and fourth types, and porcine pseudorabies virus was performed.

Animals↗

Two isozymes of clavaminate synthase central to clavulanic acid formation: cloning and sequencing of both genes from Streptomyces clavuligerus.

Clavaminate synthase (CS) is an alpha-ketoglutarate-dependent oxygenase central to the biosynthesis of clavulanic acid, a potent inhibitor of beta-lactamases. CS catalyzes the oxidative cyclization/desaturation of proclavaminic acid to clavaminic acid in a two-step process involving the intermediacy of dihydroclavaminic acid [Salowe, S. P., Krol, W. J., Iwata-Reuyl, D., & Townsend, C. A. (1991) Biochemistry 30, 2281-2292]. During the purification of CS to homogeneity from Streptomyces clavuligerus [Salowe, S. P., Marsh, E. N., & Townsend, C. A. (1990) Biochemistry 29, 6499-6508], two forms of the enzyme capable of carrying out the complete reaction having very similar molecular weights and kinetic properties were isolated by Mono-Q chromatography. The gene for each has been cloned, sequenced, and found to be significantly homologous (87% identity). The two genes so isolated, cs1 and cs2, have open reading frames of 975 and 978 nucleotides, respectively, encoding proteins of M(r) 35,347 and 35,774. These genes are located in different loci of the genome separated by > 20 kbp. This separation is large for a natural product biosynthetic pathway in bacteria where gene duplication and limited divergence are typically observed to occur within narrower confines of a gene cluster. Sequence comparisons made between cs1/cs2 and other genes encoding iron-dependent proteins involved in penicillin and cephalosporin biosynthesis in the same organism show minimal homology. Further sequence alignments made to other non-heme iron oxygenases reveal unexpected dissimilarity within the alpha-ketoglutarate-dependent class itself. The limited data available suggests evolutionary convergence among these proteins.

Amino Acid Sequence↗

Identification and nucleotide sequence of a developmentally regulated gene encoding a eukaryotic histone H1-like protein from Chlamydia trachomatis.

A lambda gt11 recombinant library of Chlamydia trachomatis serovar L2 chromosomal DNA was screened with a 29-mer synthetic oligonucleotide specific to the N-terminal amino acids of a predominant 18-kDa chlamydial protein. One recombinant clone, designated lambda gt11/L2/RKA10, was selected on the basis of its strong hybridization signal. Restriction endonuclease analysis and complete nucleotide sequencing of the recombinant revealed a 2,633-bp insert containing one complete open reading frame (ORF2) and two partial ORFs (ORF1 and ORF3). The deduced amino acid sequence of ORF2 matched perfectly at its N-terminal end with the derived amino acid sequence. The 375-bp ORF is capable of encoding a protein comprising 125 amino acids with a molecular mass of 13,689. A sequence compatible with a Shine-Dalgarno ribosome-binding site was located 9 bp upstream from the initiation codon, while the sequence distal to ORF2 revealed a rho-independent terminator. The protein, designated CTH1, possesses an estimated pI of 10.71 due to its high lysine content. This highly basic protein contains no tryptophan or phenylalanine. A protein data base search identified significant homology between CTH1 and painted sea urchin histone H1. Northern (RNA) blot analysis of Chlamydia-infected host cells demonstrated transcripts at 12 h postinfection. The recombinant plasmid encoding ORF2 expressed a gene product of approximately 18 kDa, similar to the native chlamydial protein as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein appears to represent one of the few eukaryotic histonelike proteins described to date in prokaryotes.

Amino Acid Sequence↗

The sequence of a 17,933 bp segment of Saccharomyces cerevisiae chromosome XIV contains the RHO2, TOP2, MKT1 and END3 genes and five new open reading frames.

We report the DNA sequence of a 17,933 bp fragment from the left arm of chromosome XIV of Saccharomyces cerevisiae. Analysis of the sequence reveals the presence of ten open reading frames (ORFs) larger than 100 codons. Four of these were previously identified as genes RHO2, TOP2, MKT1 and END3. Additionally, the NH2 end coding region of PMS1 is found in the 3' end of the sequence. No significant homology to any known protein has been found for the other five ORFs.

Amino Acid Sequence↗

Molecular analysis of the rpoD gene of Enterococcus faecalis.

The complete nucleotide sequence of the rpoD gene of Enterococcus faecalis ATCC19433 has been determined. This gene encodes a putative 368 amino acids (aa) polypeptide of a predicted Mr of 41842 named sigma 42. Upstream of the rpoD gene and beginning from the end of the cloned chromosomal fragment is an open reading frame encoding a putative 264-aa polypeptide. It is reminiscent of the C-terminal domain of known DNA primase from Gram-positive bacteria indicating that the E. faecalis rpoD gene is included in a macromolecular synthesis (MMS) operon, as it was described for Escherichia coli, Bacillus subtilis and Lactococcus lactis rpoD gene.

Amino Acid Sequence↗

Cloning and mapping of a novel human cDNA homologous to DROER, the enhancer of the Drosophila melanogaster rudimentary gene.

We have isolated a novel human cDNA clone that encodes a protein with 80% identity in amino acid sequence to DROER, the enhancer of the rudimentary gene in Drosophila melanogaster. The rudimentary gene product is thought to have significant enzymatic functions in the pyrimidine metabolic pathway, as well as a critical role in development of the wings. The human cDNA, termed ERH, consists of 797 nucleotides, which include an open reading frame of 312 nucleotides encoding 104 amino acids. The ERH gene was expressed in all normal human tissues examined. We assigned the ERH gene locus to chromosomal band 7q34 by fluorescence in situ hybridization.

Amino Acid Sequence↗

Characterization of two genes, glpQ and ugpQ, encoding glycerophosphoryl diester phosphodiesterases of Escherichia coli.

The nucleotide sequences of the glpQ and ugpQ genes of Escherichia coli, which both encode glycerophosphoryl diester phosphodiesterases, were determined. The glpQ gene encodes a periplasmic enzyme of 333 amino acids, produced initially with a 25 residue long signal sequence, while ugpQ codes for a cytoplasmic protein of 247 amino acids. Despite differences in size and cellular location, significant similarity in the primary structures of the two enzymes was found suggesting a common evolutionary origin. The 3' end of the ugpQ gene overlaps an open reading frame that is transcribed in the opposite direction. This open reading frame encodes a polypeptide with an unusual composition, i.e., 46 of the 146 amino acids are Gln or Asn. This polypeptide and the UgpQ protein were identified in an in vitro transcription/translation system as proteins with apparent molecular weights of 19.5 and 27 kDa, respectively.

Amino Acid Sequence↗

The recombination-activating gene 1 of Pleurodeles waltl (urodele amphibian) is transcribed in lymphoid tissues and in the central nervous system.

The recombination-activating gene 1 (RAG1) product is required for the somatic rearrangement of immunoglobulin and T-cell receptor genes. We cloned and sequenced the large continuous open reading frame coding for the salamander Pleurodeles waltl RAG1 protein. Semi-quantitative RT-PCR experiments were performed to quantify the expression of RAG1 in different tissues. The strongest signal was observed in the thymus of juvenile animals, confirming the primary lymphoid nature of that organ. Weaker expression was observed in the spleen, brain, and eyes of adults. Signals in these tissues represented 5.5%, 4.6%, and 2.0%, respectively, of the signal detected in the thymus. Expression in brain was confirmed by in situ hybridization. Similarly, low amounts of RAG1 transcripts were previously detected in the mouse brain. Moreover, the transcription of RAG1 begins as early as the neurula stages of development. These data suggest that the RAG1 protein could play a role in the central nervous system of vertebrates.

Amino Acid Sequence↗

Molecular and functional characterization of a carbon starvation gene of Escherichia coli.

Escherichia coli induces the synthesis of at least 30 proteins at the onset of carbon starvation, two-thirds of which are positively regulated by the cyclic AMP (cAMP) and cAMP receptor protein (CRP) complex. Two of the cAMP-CRP-dependent genes mapped to 14 and 93 minutes of the chromosome and are designated cstA and cstB, respectively. The cstA promoter region was cloned and localized to a 600 base-pair fragment downstream from the iron-regulated entCEBA-P15 operon. Carbon starvation-inducible transcription initiated at three sites spaced one turn of the DNA helix apart. All had--10 sequences similar to consensus E sigma 70 promoters and poor--35 sequences. Deletion of a putative CRP binding site abolished carbon starvation-mediated induction. Sequence analysis of the cstA coding region revealed the presence of three sequential open reading frames potentially encoding two hydrophobic proteins of 60,223 Da and 15,201 Da and a hydrophilic protein of 7467 Da. Overexpression of the cstA region produced starvation-inducible proteins of the expected sizes. Suggestive evidence was obtained that cstA is involved in peptide utilization.

Amino Acid Sequence↗

Sequence of the rec-2 locus of Haemophilus influenzae: homologies to comE-ORF3 of Bacillus subtilis and msbA of Escherichia coli.

The nucleotide sequence of a 4243-bp PstI fragment containing the rec-2 gene of Haemophilus influenzae was determined. The amino acid (aa) sequences of four putative proteins were deduced from the corresponding open reading frames (ORFs). The 2400-bp ORF2 accounted for rec-2, based on the sequences of DNA fragments that contained rec-2::mini-Tn10 mutations. The rec-2 gene encoded a putative 800-aa protein with a M(r) of 90,561. Sequence analysis suggested that the rec-2 product contained nine highly probable integral membrane-spanning segments. Database searches showed that rec-2 was homologous to the comE-ORF3 gene of Bacillus subtilis. This hypothesis is consistent with the known involvement of both of these genes in the passage of transforming DNA through the competent-cell envelope. Although the sequences of the other three ORFs were incomplete, sufficient data were available to allow inferences about their homologies to other genes. ORF4, which overlapped ORF1, was homologous to the Escherichia coli dnaK suppressor gene, dksA, and therefore was named dsh-1 (dnaK suppressor homolog). Mutations in dsh-1 and its putative promoter region caused a mild sensitivity to UV light, but did not affect DNA recombination. ORF3, located downstream from rec-2, was homologous to msbA, an essential gene of E. coli with extensive similarity to the ATP-dependent translocators. ORF3 was named msh-1 (msbA homolog). Mutations in msh-1 had no effects on genetic transformation. The close juxtaposition of rec-2 and msh-1 implied that the expression of msh-1 could be linked to the translation of the rec-2 ORF.

ATP-Binding Cassette Transporters↗

Amino acid sequence of a putative transposase protein of the medaka fish transposable element Tol2 deduced from mRNA nucleotide sequences.

Tol2 is a terminal-inverted repeat transposable element of the medaka fish Oryzias latipes. It is one of a few elements of this class so far demonstrated to be active in vertebrates, thus providing a unique tool for establishing a gene tagging system. For the purpose of identifying its transposase, we analyzed the structures of mRNAs originating from the Tol2 element. The results indicated that transcription of Tol2 is initiated at several sites, the four open reading frames in Tol2 roughly corresponding to exons, and that two main forms of mRNAs, covering exons 1-4 and exons 2-4, are present in medaka fish cells. One or both of these mRNAs are likely to encode a transposase, the amino acid sequence of which was deduced.

Amino Acid Sequence↗

A Porphyromonas gingivalis genetic locus encoding a heme transport system.

Porphyromonas gingivalis has been implicated in the onset and progression of periodontitis and the availability of hemin for in vitro growth has been associated with virulence of the bacterium in animal models. We report here the cloning and sequence analysis of a P. gingivalis TonB-linked outer membrane receptor gene tlr. This gene was previously identified as a TonB-linked adhesin gene tla and shown to be essential for growth at low concentrations of hemin. The tlr gene is immediately downstream of four open reading frames (htrABCD) that encode a putative ATP binding cassette transport system with sequence similarlity to heme transport systems of other bacteria. Analysis of P. gingivalis W50 mRNA revealed that the htrABCD genes are cotranscribed similar to hemin transport genes of other bacteria.

ATP-Binding Cassette Transporters↗

Discovery and distribution of super-integrons among pseudomonads.

Until recently, integrons (systems for acquisition and expression of new genetic materials) have been associated generally with antibiotic resistance gene cassettes. The discovery of 'super-integrons' in Vibrionaceae suggests a greater impact of this gene acquisition mechanism on bacterial genome evolution than initially believed. Super-integrons may contain more than 100 gene cassettes and may encode other determinants, including biochemical functions or virulence factors. Here, we report the genetic organization of a super-integron from Pseudomonas alcaligenes ATCC 55044. This is the first evidence of a super-integron in a non-pathogenic bacterium, one which is widely distributed in a great number of ecological niches such as soil and aquatic habitats. Here, the sequence composition, open reading frame (ORF) content and organization of In55044 are described and found to have features intermediate between the multidrug-resistant integrons and the Vibrio cholerae super-integron. Similar structures are inferred to be present in several Pseudomonas species, based on polymerase chain reaction (PCR) experiments.

Amino Acid Sequence↗

Cloning and characterization of a novel splice variant of human Rab18 gene (RAB18).

Rab GTPase proteins are a kind of small GTP-binding proteins, which functions mainly focus on regulating interacellular trafficking pathways during vesicular transport. To date, 60 distinct human RAB proteins have been identified. RAB18 gene is discovered from endothelial cells. Its function is considered as endosomes and plasma membrane recycling. Research indicates RAB18 may relate to inflammation and some kinds of tumor. Here we report a splice variant of RAB18, which is 2571 bp in length and has an open reading frame coding a predicted 235 amino-acids protein. RT-PCR shows that the cDNA has different expression pattern with RAB18 and is highly expressed in testis.

Alternative Splicing↗

Mobile elements carrying ermF and tetQ genes in gram-positive and gram-negative bacteria.

Bacteroides spp. conjugative transposon Tn5030 is 150 kb which includes a 43 kb characterized region containing a number of defined genes and an open reading frame (ORF). The 43 kb region is organized with the ORF1 immediately upstream from the ermF gene, coding for an rRNA methylase, then an unknown 20 kb region downstream followed by the tetQ gene (coding for a ribosomal protection protein) then the rteA and rteB genes. The role of ORF1 is unclear; rteA is a putative sensor and rteB a regulator. Thirty-seven (62%) of 60 isolates, representing one gram-positive anaerobic and 13 gram-negative anaerobic species, co-transferred the ermFand tetQ genes to an unrelated Enterococcus faecalis recipient. We used the polymerase chain reaction to show the linkage between ORF1, ermF, tetQ, rteA and rteB. Our data suggest that the ORF1 gene product may participate in the transfer of the ermF gene with or without the ORF1-rteB region and has homology to bacterial transposases. Isolates that co-transferred the ermF and tetQ genes carried and transferred the rteB gene, suggesting that the rteB gene product may be important in transfer of the 43 kb ORF1-rteB region to E. faecalis. The rteB gene product is not required when ermF is transferred independently of tetQ.

Bacterial Proteins↗

The gene encoding a novel halorhodopsin-like protein of extremely halophilic archaeon Haloarcula japonica strain TR-1.

The gene encoding the halorhodopsin (hR)-like protein was cloned and sequenced from Haloarcula japonica strain TR-1. The structural gene consisted of an open reading frame of 828 nucleotides encoding 276 amino acids. The deduced amino acid sequence of the Ha. japonica hR-like protein showed the highest homology to those of cruxhalorhodopsins. Furthermore, we have demonstrated that the Ha. japonica chR gene is transcriptionally induced by light.

Amino Acid Sequence↗