Expression of Bacillus amyloliquefaciens amylase and Vibrio alginolyticus protease A fusion genes

Previously we reported [Deane, S. M., Maharaj, R., Robb, F. T. & Woods, D. R. (1987) Journal of General Microbiology 133, 2295-2302] that the production of a Vibrio alginolyticus SDS-resistant alkaline serine protease (Pro A) cloned in Escherichia coli was characterized by a 12 h delay between the synthesis of an inactive precursor and secretion of active Pro A. Replacement of the V. alginolyticus promoter region by the alpha-amylase promoter region from Bacillus amyloliquefaciens resulted in the simultaneous synthesis and secretion of Pro A in E. coli. The V. alginolyticus pro A gene cloned on a shuttle vector did not produce active Pro A in Bacillus subtilis. Although Pro A has a typical Gram-positive signal sequence, it was not functional in B. subtilis. Replacement of the Pro A signal sequence with the alpha-amylase signal sequence resulted in the production of active Pro A in B. subtilis.

Six areas lead national early immunization drive

On June 13, 1991, President George Bush announced in a White House ceremony a local planning effort to break down barriers and provide better access to immunization in six representative localities "to solve the problem of late immunization." (children need to be immunized appropriately by their second birthday, not just in time for school.). The community "Immunization Action Plans" (IAP) are one of several Federal, State, and local responses to an outbreak of measles that produced 27,600 cases and 89 deaths in 1990. The community effort and subsequent early childhood immunization plans around the country are also part of a much broader effort initiated by Secretary Sullivan as a Healthy People Year 2000 goal to increase immunization levels to at least 90 percent for the nation's children by their second birthday. These efforts also respond to 13 recommendations for improving immunization availability made by the National Vaccine Advisory Committee in January 1991. The recommendations focused on improvements in the management of immunization delivery and in methods for measuring immunization status, increasing appropriate consumer demand, and other prevention needs. Although measles prompted the action, the immunization initiative is aimed also at eight other communicable childhood diseases--diphtheria, tetanus, pertussis or whooping cough, poliomyelitis, mumps, rubella, and Haemophilus influenza type b that causes bacterial meningitis, and hepatitis B. Details are described of the immunization action plans developed by Dallas, TX; Maricopa County (Phoenix), AZ; South Dakota; Detroit, MI; San Diego, CA; and Philadelphia, PA, to ensure that children are fully immunized not just by the time they enter school but by age 2 years. The six were chosen by the Centers for Disease Control as representative of many without adequate childhood immunization coverage.

Identification of indigo-related pigments produced by Escherichia coli containing a cloned Rhodococcus gene

Pigments produced by Escherichia coli containing a cloned piece of DNA from Rhodococcus sp. ATCC 21145 were extracted in chloroform and separated into blue and pink components. Evidence from TLC, NMR spectroscopy, absorption spectrum analysis and solubility behaviour suggested that the blue pigment was indigo and the pink pigment was indirubin, a structural isomer of indigo. The proposed pathway for pigment production on LB agar involves the conversion of tryptophan to indole by tryptophanase of E. coli and the oxidation of indole to indigo by the product of the cloned Rhodococcus DNA insert.

Construction of an insertional-inactivation cloning vector for Escherichia coli using a Rhodococcus gene for indigo production

pSLH8, an insertional-inactivation cloning vector for Escherichia coli has been constructed by inserting a pigment gene (probably encoding an indole dioxygenase) from Rhodococcus sp. ATCC 21145 into pUC18. Wild-type E. coli colonies containing pSLH8 produce insoluble indigo and turn dark blue on unsupplemented LB agar. Insertion of DNA fragments into the unique BamHI, EcoRI, EcoRV, HindIII, PstI, SphI and SstI polylinker cloning sites disrupts the reading frame of the fully sequenced pigment gene and results in unpigmented colonies. pSLH8 may be an attractive alternative to pUC18 and similar plasmids because it does not require specifically mutated host strains or an expensive substrate for colour development.

Homology of a candidate spermatogenic gene from the mouse Y chromosome to the ubiquitin-activating enzyme E1

The Sxr (sex-reversed) region, a fragment of the Y chromosome short arm, can cause chromosomally female XXSxr or XSxrO mice to develop as sterile males. The original Sxr region, termed Sxra, encodes: Tdy, the primary sex-determining gene; Hya, the controlling or structural locus for the minor transplantation antigen H-Y; gene(s) controlling the expression of the serologically detected male antigen (SDMA); Spy, a gene(s) required for the survival and proliferation of A spermatogonia during spermatogenesis; Zfy-1/Zfy-2, zinc-finger-containing genes of unknown function; and Sry, which is probably identical to Tdy. A deletion variant of Sxra, termed Sxrb, which lacks Hya, SDMA expression, Spy and some Zfy-2 sequences, makes positional cloning of these genes possible. We report here the isolation of a new testis-specific gene, Sby, mapping to the DNA deleted from the Sxrb region (the delta Sxrb interval). Sby has extensive homology to the X-linked human ubiquitin-activating enzyme E1. The critical role of this enzyme in nuclear DNA replication together with the testis-specific expression of Sby suggests Sby as a candidate for the spermatogenic gene Spy.

Characterization of the Butyrivibrio fibrisolvens glgB gene, which encodes a glycogen-branching enzyme with starch-clearing activity

A Butyrivibrio fibrisolvens H17c glgB gene, was isolated by direct selection for colonies that produced clearing on starch azure plates. The gene was expressed in Escherichia coli from its own promoter. The glgB gene consisted of an open reading frame of 1,920 bp encoding a protein of 639 amino acids (calculated Mr, 73,875) with 46 to 50% sequence homology with other branching enzymes. A limited region of 12 amino acids showed sequence similarity to amylases and glucanotransferases. The B. fibrisolvens branching enzyme was not able to hydrolyze starch but stimulated phosphorylase alpha-mediated incorporation of glucose into alpha-1,4-glucan polymer 13.4-fold. The branching enzyme was purified to homogeneity by a simple two-step procedure; N-terminal sequence and amino acid composition determinations confirmed the deduced translational start and amino acid sequence of the open reading frame. The enzymatic properties of the purified enzyme were investigated. The enzyme transferred chains of 5 to 10 (optimum, 7) glucose units, using amylose and amylopetin as substrates, to produce a highly branched polymer.

Cloning, nucleotide sequence, and enzymatic characterization of an alpha-amylase from the ruminal bacterium Butyrivibrio fibrisolvens H17c

A Butyrivibrio fibrisolvens amylase gene was cloned and expressed by using its own promoter on the recombinant plasmid pBAMY100 in Escherichia coli. The amylase gene consisted of an open reading frame of 2,931 bp encoding a protein of 976 amino acids with a calculated Mr of 106,964. In E. coli(pBAMY100), more than 86% of the active amylase was located in the periplasm, and TnphoA fusion experiments showed that the enzyme had a functional signal peptide. The B. fibrisolvens amylase is a calcium metalloenzyme, and three conserved putative calcium-binding residues were identified. The amylase showed high sequence homology with other alpha-amylases in the three highly conserved regions which constitute the active centers. These and other conserved regions were located in the N-terminal half, and no similarity with any other amylase was detected in the remainder of the protein. Deletion of approximately 40% of the C-terminal portion of the amylase did not result in loss of amylolytic activity. The B. fibrisolvens amylase was identified as an endo-alpha-amylase by hydrolysis of the Phadebas amylase substrate, hydrolysis of gamma-cyclodextrin to maltotriose, maltose, and glucose and the characteristic shape of the blue value and reducing sugar curves. Maltotriose was the major initial hydrolysis product from starch, although extended incubation resulted in its hydrolysis to maltose and glucose.

An efficient cyanide-degrading Bacillus pumilus strain

A Gram-positive, aerobic, endospore-forming bacterium was isolated by an enrichment technique for the ability to degrade cyanide and was identified as a Bacillus pumilus strain. The bacterium rapidly degraded 100 mg l-1 of free cyanide in the absence of added inorganic and organic substances. The ability to degrade cyanide was linked to the growth phase and was not exhibited before late exponential/early stationary phase. Cyanide-degrading activity could not be induced before this time by the addition of 20 mg cyanide l-1. Production of the cyanide-degrading activity required 0.01 mg Mn2+ l-1 and did not occur at Mn2+ concentrations below 0.002 mg l-1. Cyanide-degrading activity was intracellular and cell-free extracts rapidly degraded cyanide.

Nucleotide sequence and analysis of the Vibrio alginolyticus scr repressor-encoding gene (scrR)

The nucleotide sequence of the Vibrio alginolyticus scr repressor-encoding gene (scrR) was determined. The deduced amino acid sequence of the scr repressor was homologous with the gal, lac and cyt repressors of Escherichia coli and contained a helix-turn-helix DNA binding domain. Although the scrR gene encoded a protein which was required for the regulation of the V. alginolyticus sucrose utilization system, a particular deletion in the scrR gene could not be complemented in trans. The lack of complementation was discussed in terms of the possible involvement of a cis regulatory element or interference by the truncated scr repressor.

Protein turnover in exponential and stationary phase Vibrio cells

Vibrio strain 14 supports phage alpha 3a growth in standing stationary phase cells but not in shaking (aerated) stationary phase cells. In exponential cells, protein was turned over at 1.8% h-1, and the rate was increased by starvation or inhibition of protein synthesis. In shaking stationary phase cells the rate of protein turnover was low (1.0% h-1) for proteins synthesised during growth but high (20% h-1) for recently synthesised proteins. In contrast recently synthesised proteins in standing stationary phase cells were stable over 60 min and proteins synthesised during growth were turned over at 2.9% h-1. ppGpp and pppGpp were detected in exponential cells, but were not detected in stationary phase cells.

"America Responds to AIDS": its content, development process, and outcome

During the 1987-90 period, five phases of new AIDS information materials were released to the general public in the ARTA campaign, including a national mailer. The five were "General Awareness: Humanizing AIDS" in October 1987, "Understanding AIDS," the national mailout, April 1988, "Women at Risk/Multiple Partner, Sexually Active Adults," October 1988, "Parents and Youth," May 1989, and "Preventing HIV Infection and AIDS: Taking The Next Steps," July 1990. From planning to implementation to evaluation, ARTA is based on well-established theory and practice. Initially, the campaign was a response to an immediate crisis. It has evolved into the deliberate and systematic development of objectives to combat a chronic problem. ARTA represents one of the most comprehensive formative research processes in the history of public service campaigns. The dynamic process of carefully developing each new phase to include such important entities as State and local health agencies and community-based organizations is at least as important as the quality of the end materials. The objectives of each new phase are based on the needs of the public and of specific audiences. Maximum input from all relevant constituencies is obtained to ensure that they support the campaign's objectives and implementation strategy.

Nucleotide sequence and analysis of the Vibrio alginolyticus sucrose uptake-encoding region

The nucleotide sequence of the Vibrio alginolyticus sucrose uptake-encoding region was determined, and contained two genes, scrA and scrK. The scrA gene encodes an enzyme IISucrose (EIIScr) protein of the phosphoenolpyruvate dependent phosphotransferase system and the scrK gene encodes a fructokinase. The deduced amino acid (aa) sequence for the V. alginolyticus EIIScr protein was homologous with the EIIScr proteins from Streptococcus mutans, Salmonella typhimurium (pUR400 system) and Bacillus subtilis. The deduced aa sequence for the V. alginolyticus fructokinase was homologous with the Escherichia coli enzymes, 6-phosphofructokinase (isoenzyme 2) and ribokinase. Transposon phoA mutagenesis experiments indicated that the EIIScr protein was a membrane-bound protein with a region that extended into the periplasm.

Molecular analysis of the Bacteroides fragilis recA gene

The nucleotide sequence of a 2.5-kb DNA segment containing the Bacteroides fragilis recA gene was determined. The coding region of the recA gene specifies a protein of 318 amino acids. The RecA protein of B. fragilis shows significant homology with that of Escherichia coli, Thiobacillus ferrooxidans, Pseudomonas aeruginosa and Proteus mirabilis. No SOS box characteristic of LexA-regulated promoters could be identified in the 5'-noncoding region of the B. fragilis recA gene. Promoter activity of the cloned recA gene in E. coli was located within a 113-bp fragment of the B. fragilis DNA by in vitro construction of operon fusions with a promoterless lacZ gene. The transcription start point for this gene in B. fragilis was determined by primer extension analysis.

Sequencing and expression of a cellodextrinase (ced1) gene from Butyrivibrio fibrisolvens H17c cloned in Escherichia coli

The nucleotide sequence of a 2.314 kb DNA segment containing a gene (ced1) expressing cellodextrinase activity from Butyrivibrio fibrisolvens H17c was determined. The B. fibrisolvens H17c gene was expressed from a weak internal promoter in Escherichia coli and a putative consensus promoter sequence was identified upstream of a ribosome binding site and a GTG start codon. The complete amino acid sequence (547 residues) was deduced and homology was demonstrated with the Clostridium thermocellum endoglucanase D (EGD), Pseudomonas fluorescens var. cellulosa endoglucanase (EG), and a cellulase from the avocado fruit (Persea americana). The ced1 gene product Ced1 showed cellodextrinase activity and rapidly hydrolysed short-chain cellodextrins to yield either cellobiose or cellobiose and glucose as end products. The Ced1 enzyme released cellobiose from p-nitrophenyl-beta-D-cellobioside and the enzyme was not inhibited by methylcellulose, an inhibitor of endoglucanase activity. Although the major activity of the Ced1 enzyme was that of a cellodextrinase it also showed limited activity against endoglucanase specific substrates [carboxymethylcellulose (CMC), lichenan, laminarin and xylan]. Analysis by SDS-polyacrylamide gel electrophoresis with incorporated CMC showed a major activity band with an apparent Mr of approximately 61,000. The calculated Mr of the ced1 gene product was 61,023.

Studies on Clostridium acetobutylicum glnA promoters and antisense RNA

The Clostridium acetobutylicum glnA gene has two transcript start sites under the control of promoters p1 and p2. Initiation of transcription was regulated by nitrogen and a downstream region was implicated in the regulation of transcript initiation by nitrogen in Escherichia coli. Putative antisense RNA was produced from a single downstream transcript start site under the control of p3. An up-promoter mutation in p3 resulted in lower levels of glutamine synthetase (GS) activity. Putative antisense RNA had a role in down-regulating GS expression but was not involved in regulation by nitrogen. Deletion of downstream inverted repeat sequences resulted in very low levels of GS activity.

Complementation of Escherichia coli sigma 54 (NtrA)-dependent formate hydrogenlyase activity by a cloned Thiobacillus ferrooxidans ntrA gene

The ntrA gene of Thiobacillus ferrooxidans was cloned by complementation of an Escherichia coli ntrA mutant that was unable to produce gas via the sigma 54 (NtrA)-dependent formate hydrogenlyase pathway. Analysis of the DNA sequence showed that the T. ferrooxidans ntrA gene coded for a protein of 475 amino acids (calculated Mr, 52,972). The T. ferrooxidans NtrA protein had 49, 44, 33, and 18% amino acid similarity with the NtrA proteins of Klebsiella pneumoniae, Azotobacter vinelandii, Rhizobium meliloti, and Rhodobacter capsulatus, respectively. The ability of the T. ferrooxidans NtrA protein to direct transcription from sigma 54-dependent promoters was demonstrated in E. coli by using fdhF-lacZ and nifH-lacZ fusions. An open reading frame coding for a protein of 241 amino acids (calculated Mr, 27,023) was situated 12 base pairs upstream of the T. ferrooxidans ntrA gene. Comparison of this protein with the product of the open reading frame ORF1, located upstream of the R. meliloti ntrA gene, showed that the two proteins had 55% amino acid similarity. The cloned T. ferrooxidans ntrA gene was expressed in E. coli from a promoter located within the ORF1 coding region.

Cloning, sequencing and analysis of expression of a Butyrivibrio fibrisolvens gene encoding a beta-glucosidase

The cloning, expression and nucleotide sequence of a 3.74 kb DNA segment on pLS215 containing a beta-glucosidase gene (bglA) from Butyrivibrio fibrisolvens H17c was investigated. The B. fibrisolvens bglA open reading frame (ORF) of 2490 bp encoded a beta-glucosidase of 830 amino acid residues with a calculated Mr of 91,800. In Escherichia coli C600(pLS215) cells the beta-glucosidase was localized in the cytoplasm and these cells produced an additional protein with an apparent Mr of approximately 94,000. The bglA gene was expressed from its own regulatory region in E. coli and a single mRNA initiation point was identified upstream of the bglA ORF and adjacent to a promoter consensus sequence. The primary structure of the beta-glucosidase showed greater than 40% similarity with a domain of 237 amino acids present in the beta-glucosidases of Kluyveromyces fragilis and Clostridium thermocellum. The B. fibrisolvens beta-glucosidase hydrolysed cellobiose to a limited extent, cellotriose to cellobiose and glucose, and cellotetraose and cellopentaose to predominantly glucose.

Induction and repair of DNA strand breaks in Bacteroides fragilis

Alkaline sucrose gradient sedimentation was used to establish whether strand breakage and repair take place in the DNA of UV-irradiated Bacteroides fragilis during the removal of pyrimidine dimers. A B. fragilis wild-type strain and two of its repair mutants, a mitomycin C sensitive mutant (MTC25) having wild-type levels of UV survival, and a UV-sensitive, mitomycin C sensitive mutant (UVS9), were investigated. Under anaerobic conditions, far-UV irradiation induced metabolically regulated strand breakage and resynthesis in the wild-type strain, but this was markedly reduced in both the MTC25 and UVS9 mutants. Approximately half of the strand breaks generated by the various strains were rejoined during further holding in buffer. Under replicating conditions, complete repair of strand breaks in the wild type was observed. Caffeine treatment under anaerobic conditions caused direct DNA strand breakage in B. fragilis cells but did not inhibit UV-induced breakage or repair.

Structure of a Rhodococcus gene encoding pigment production in Escherichia coli

A 2.1 kbp DNA fragment from Rhodococcus strain ATCC 21145 gave rise to the production of blue and pink pigments in Escherichia coli when cloned downstream of a strong promoter. The sequence of this DNA fragment contains a single open reading frame with a putative ribosome-binding site, potentially coding for a single protein of Mr 42,560. Deletion analysis and in vitro transcription-translation experiments support the hypothesis that pigment production in E. coli is due to a single enzyme whose catalytic activity is still unknown. This small pigment gene may become useful for the development of a new generation of chromogenic cloning vectors which do not require expensive substrates for the detection of gene expression.

Expression and regulation of a Bacteroides fragilis sucrose utilization system cloned in Escherichia coli

A Bacteroides fragilis strain isolated from human feces was the source of chromosomal DNA in the construction of plasmid pBS100. The cloned 6-kilobase insert of plasmid pBS100 conferred a sucrose positivity phenotype on transformed cells of Escherichia coli JA221. E. coli JA221(pBS100) cells were able to utilize sucrose as the sole source of carbon because of the presence of sucrase enzyme and sucrose uptake activities. Sucrase activity was inducible in B. fragilis but constitutive in E. coli JA221(pBS100) cells. In sucrose-minimal medium, both B. fragilis and E. coli JA221(pBS100) produced intracellular and extracellular sucrase activities throughout the growth cycle. Osmotic shock experiments performed on E. coli JA221(pBS100) indicated that up to 55% of the sucrase activity was localized in the periplasmic space, 30% was in the cytoplasm, and the remaining 15% was in the cell-free extracellular supernatant fluid. B. fragilis and E. coli JA221(pBS100) actively transported sucrose. Sucrose uptake was induced by sucrose in B. fragilis, whereas the uptake activity in E. coli JA221(pBS100) was constitutive. E. coli JA221(pBS100) appeared to transport sucrose by a phosphotransferase-independent system. B. fragilis transported sucrose only under strictly anaerobic conditions. No uptake activity was detected under aerobic conditions with or without addition of catalase.

Cloning of Bacteroides fragilis plasmid genes affecting metronidazole resistance and ultraviolet survival in Escherichia coli

Since reduced metronidazole causes DNA damage, resistance to metronidazole was used as a selection method for the cloning of Bacteroides fragilis genes affecting DNA repair mechanisms in Escherichia coli. Genes from B. fragilis Bf-2 were cloned on a recombinant plasmid pMT100 which made E. coli AB1157 and uvrA, B, and C mutant strains more resistant to metronidazole, but more sensitive to far uv irradiation under aerobic conditions. The loci affecting metronidazole resistance and uv sensitivity were linked and located on a 5-kb DNA fragment which originated from the small 6-kb cryptic plasmid pBFC1 present in B. fragilis Bf-2 cells.

Rapid detection of Pneumocystis carinii in bronchoalveolar lavage samples by using Cellufluor staining

Cellufluor (Calcofluor white) has been found to be a useful, rapid chemofluorescent stain for detection of Pneumocystis carinii cysts in bronchoalveolar lavage samples. When compared with toluidine blue O and Giemsa stains on 45 specimens (22 positive and 23 negative), the sensitivity and specificity of the Cellufluor stain were 95 and 100%, respectively.

Molecular analysis of a novel glutamine synthetase of the anaerobe Bacteroides fragilis

The nucleotide sequence of a 2777 bp DNA segment containing the Bacteroides fragilis glnA gene was determined. The B. fragilis glnA open reading frame of 2187 bp encoded a glutamine synthetase (GS) subunit of 729 amino acid residues with a calculated Mr of 82,827. The apparent Mr of the GS subunit determined by SDS-PAGE was approximately 75,000. A single mRNA transcription start point was identified upstream of the B. fragilis glnA open reading frame. The B. fragilis GS subunit is approximately 270 and 400 amino acids longer than the GSI and GSII subunits, respectively, of other prokaryotes and eukaryotes. The GSI and GSII holoenzymes are dodecamers and octamers respectively, whereas the GS of B. fragilis is a hexamer. Although GSI and GSII subunits show amino acid similarity in five conserved regions, this similarity is not strongly conserved in the B. fragilis GS. The GS of B. fragilis is not regulated by adenylylation and lacks the adenylylation site. It also lacks the Trp residue associated with the active site in GSI and GSII enzymes from other prokaryotes and eukaryotes.

Homology between hydroxybutyryl and hydroxyacyl coenzyme A dehydrogenase enzymes from Clostridium acetobutylicum fermentation and vertebrate fatty acid beta-oxidation pathways

The enzymes NAD-dependent beta-hydroxybutyryl coenzyme A dehydrogenase (BHBD) and 3-hydroxyacetyl coenzyme A (3-hydroxyacyl-CoA) dehydrogenase are part of the central fermentation pathways for butyrate and butanol production in the gram-positive anaerobic bacterium Clostridium acetobutylicum and for the beta oxidation of fatty acids in eucaryotes, respectively. The C. acetobutylicum hbd gene encoding a bacterial BHBD was cloned, expressed, and sequenced in Escherichia coli. The deduced primary amino acid sequence of the C. acetobutylicum BHBD showed 45.9% similarity with the equivalent mitochondrial fatty acid beta-oxidation enzyme and 38.4% similarity with the 3-hydroxyacyl-CoA dehydrogenase part of the bifunctional enoyl-CoA hydratase:3-hydroxyacyl-CoA dehydrogenase from rat peroxisomes. The pig mitochondrial 3-hydroxyacyl-CoA dehydrogenase showed 31.7% similarity with the 3-hydroxyacyl-CoA dehydrogenase part of the bifunctional enzyme from rat peroxisomes. The phylogenetic relationship between these enzymes supports a common evolutionary origin for the fatty acid beta-oxidation pathways of vertebrate mitochondria and peroxisomes and the bacterial fermentation pathway.