Protection against bacteriocin 28b in Serratia matcescens is apparently not related to the expression of an immunity gene

1995 ◽  
Vol 41 (3) ◽  
pp. 217-226 ◽  
Author(s):  
Margarita Beatriz Viejo ◽  
Josefina Enfedaque ◽  
Joan Francesc Guasch ◽  
Santiago Ferrer ◽  
Miguel Regué

The gene encoding bacteriocin 28b from Serratia marcescens N28b (bss gene) has been cloned in Escherichia coli and its nucleotide sequence has been determined. The genetic determinants coding for other well-characterized bacteriocins from enterobacteria (colicins) are located in plasmids and they have always been shown to contain a gene responsible for immunity located downstream from the bacteriocin structural gene. In some cases there is another gene located downstream from the immunity gene, which is responsible for bacteriocin release. Analysis of bacteriocin 28b release and the sensitivity to this bacteriocin of E. coli strains harbouring recombinant plasmids containing the bss gene showed that bacteriocin 28b is not released from the cell in these strains and that their phenotypic insensitivity is not associated with any region close to the structural gene. The nucleotide sequence of the region downstream from the bss gene contains two putative open reading frames transcribed in the opposite direction to the bss gene. These open reading frames apparently encode proteins that seem not to be involved in bacteriocin immunity or release. Moreover, a S. marcescens N28b genomic library was screened and no immunity gene was found. Therefore, bacteriocin 28b differs greatly from the bacteriocins from other enterobacteria, and in the following senses it is unique: firstly, the gene encoding bacteriocin 28b seems to be located on the chromosome, and secondly, insensitivity to this bacteriocin in S. marcescens N28b is not associated with the expression of an immunity gene.Key words: bacteriocin, pore-forming colicins, immunity, Serratia marcescens.

2001 ◽  
Vol 69 (3) ◽  
pp. 1961-1966 ◽  
Author(s):  
Hilde E. Smith ◽  
Herma Buijs ◽  
Henk J. Wisselink ◽  
Norbert Stockhofe-Zurwieden ◽  
Mari A. Smits

ABSTRACT Within Streptococcus suis serotype 2, pathogenic, weakly pathogenic, and nonpathogenic strains can be found. We introduced a genomic library of a pathogenic strain into a weakly pathogenic strain. After infection of the library into young piglets pathogenic transformants were selected. One specific transformant containing a 3-kb fragment of the pathogenic strain appeared to be dominantly enriched in diseased pigs. The observed enrichment was not tissue specific. The selected fragment, when introduced into two different weakly pathogenic strains, increased the virulence of these strains considerably. In contrast, introduction of the corresponding fragment of a weakly pathogenic strain had only minor effects on virulence. Nucleotide sequence analysis of the selected fragment of the pathogenic strain revealed the presence of two potential open reading frames, both of which were found to be mutated in the corresponding fragment of the weakly pathogenic strain. These data strongly suggest that the selected fragment contains determinants important for virulence.


2002 ◽  
Vol 83 (11) ◽  
pp. 2869-2877 ◽  
Author(s):  
F. van der Wilk ◽  
A. M. Dullemans ◽  
M. Verbeek ◽  
J. F. J. M. van den Heuvel

The complete nucleotide sequence of an ophiovirus associated with lettuce big-vein disease has been elucidated. The genome consisted of four RNA molecules of approximately 7·8, 1·7, 1·5 and 1·4 kb. Virus particles were shown to contain nearly equimolar amounts of RNA molecules of both polarities. The 5′- and 3′-terminal ends of the RNA molecules are largely, but not perfectly, complementary to each other. The virus genome contains seven open reading frames. Database searches with the putative viral products revealed homologies with the RNA-dependent RNA polymerases of rhabdoviruses and Ranunculus white mottle virus, and the capsid protein of Citrus psorosis virus. The gene encoding the viral polymerase appears to be located on the RNA segment 1, while the nucleocapsid protein is encoded by the RNA3. No significant sequence similarities were observed with other viral proteins. In spite of the morphological resemblance with species in the genus Tenuivirus, the ophioviruses appear not to be evolutionary closely related to this genus nor any other viral genus.


2009 ◽  
Vol 75 (10) ◽  
pp. 3106-3114 ◽  
Author(s):  
Jessica Rehdorf ◽  
Christian L. Zimmer ◽  
Uwe T. Bornscheuer

ABSTRACT While the number of available recombinant Baeyer-Villiger monooxygenases (BVMOs) has grown significantly over the last few years, there is still the demand for other BVMOs to expand the biocatalytic diversity. Most BVMOs that have been described are dedicated to convert efficiently cyclohexanone and related cyclic aliphatic ketones. To cover a broader range of substrate types and enantio- and/or regioselectivities, new BVMOs have to be discovered. The gene encoding a BVMO identified in Pseudomonas putida JD1 converting aromatic ketones (HAPMO; 4-hydroxyacetophenone monooxygenase) was amplified from genomic DNA using SiteFinding-PCR, cloned, and functionally expressed in Escherichia coli. Furthermore, four other open reading frames could be identified clustered around this HAPMO. It has been suggested that these proteins, including the HAPMO, might be involved in the degradation of 4-hydroxyacetophenone. Substrate specificity studies revealed that a large variety of other arylaliphatic ketones are also converted via Baeyer-Villiger oxidation into the corresponding esters, with preferences for para-substitutions at the aromatic ring. In addition, oxidation of aldehydes and some heteroaromatic compounds was observed. Cycloketones and open-chain ketones were not or poorly accepted, respectively. It was also found that this enzyme oxidizes aromatic ketones such as 3-phenyl-2-butanone with excellent enantioselectivity (E ≫100).


2002 ◽  
Vol 70 (4) ◽  
pp. 1896-1908 ◽  
Author(s):  
Jürgen Recktenwald ◽  
Herbert Schmidt

ABSTRACT In this study we determined the complete nucleotide sequence of Shiga toxin 2e-encoding bacteriophage φP27, isolated from the Shiga toxin-producing Escherichia coli patient isolate 2771/97. φP27 is integrated as a prophage in the chromosomal yecE gene. This integration generates identity segments of attL and attR sites with lengths of 11 nucleotides. The integrated prophage genome has a size of 42,575 bp. We identified 58 open reading frames (ORFs), each with a length of >150 nucleotides. The deduced proteins of 44 ORFs showed significant homologies to other proteins present in sequence databases, whereas 14 putative proteins did not. For 29 proteins, we could deduce a putative function. Most of these are related to the basic phage propagation cycle. The φP27 genome represents a mosaic composed of genetic elements which are obviously derived from related and unrelated phages. We identified five short linker sequences of 22 to 151 bp in the φP27 sequence which have also been detected in a couple of other lambdoid phages. These linkers are located between functional modules in the phage genome and are thought to play a role in genetic recombination. Although the overall DNA sequence of φP27 is not highly related to other known phages, the data obtained demonstrate a typical lambdoid genome structure.


2007 ◽  
Vol 73 (8) ◽  
pp. 2491-2497 ◽  
Author(s):  
Stephan Bathe ◽  
Paul R. Norris

ABSTRACT Genes of Sulfolobus metallicus that appeared to be upregulated in relation to growth on either ferrous iron or sulfur were identified using subtractive hybridization of cDNAs. The genes upregulated during growth on ferrous iron were found in a cluster, and most were predicted to encode membrane proteins. Quantitative reverse transcription-PCR of cDNA showed upregulation of most of these genes during growth on ferrous iron and pyrite compared to results during growth on sulfur. The highest expression levels observed included those for genes encoding proteins with similarities to cytochrome c oxidase subunits and a CbsA-like cytochrome. The genes identified here that may be involved in oxidation of ferrous iron by S. metallicus are termed fox genes. Of three available genomes of Sulfolobus species (S. tokodaii, S. acidocaldarius, and S. solfataricus), only that of S. tokodaii has a cluster of highly similar open reading frames, and only S. tokodaii of these three species was also able to oxidize ferrous iron. A gene encoding sulfur oxygenase-reductase was identified as the source of the dominant transcript in sulfur-grown cells of S. metallicus, with the predicted protein showing high identities to the previously described examples from S. tokodaii and species of Acidianus.


2002 ◽  
Vol 68 (3) ◽  
pp. 1220-1227 ◽  
Author(s):  
Masayuki Hashimoto ◽  
Mitsuru Fukui ◽  
Kouichi Hayano ◽  
Masahito Hayatsu

ABSTRACT Rhizobium sp. strain AC100, which is capable of degrading carbaryl (1-naphthyl-N-methylcarbamate), was isolated from soil treated with carbaryl. This bacterium hydrolyzed carbaryl to 1-naphthol and methylamine. Carbaryl hydrolase from the strain was purified to homogeneity, and its N-terminal sequence, molecular mass (82 kDa), and enzymatic properties were determined. The purified enzyme hydrolyzed 1-naphthyl acetate and 4-nitrophenyl acetate indicating that the enzyme is an esterase. We then cloned the carbaryl hydrolase gene (cehA) from the plasmid DNA of the strain and determined the nucleotide sequence of the 10-kb region containing cehA. No homologous sequences were found by a database homology search using the nucleotide and deduced amino acid sequences of the cehA gene. Six open reading frames including the cehA gene were found in the 10-kb region, and sequencing analysis shows that the cehA gene is flanked by two copies of insertion sequence-like sequence, suggesting that it makes part of a composite transposon.


1999 ◽  
Vol 65 (7) ◽  
pp. 2871-2876 ◽  
Author(s):  
Sandra Iurescia ◽  
Andrea M. Marconi ◽  
Daniela Tofani ◽  
Augusto Gambacorta ◽  
Annalisa Paternò ◽  
...  

ABSTRACT The M1 strain, able to grow on β-myrcene as the sole carbon and energy source, was isolated by an enrichment culture and identified as a Pseudomonas sp. One β-myrcene-negative mutant, called N22, obtained by transposon mutagenesis, accumulated (E)-2-methyl-6-methylen-2,7-octadien-1-ol (or myrcen-8-ol) as a unique β-myrcene biotransformation product. This compound was identified by gas chromatography-mass spectrometry. We cloned and sequenced the DNA regions flanking the transposon and used these fragments to identify the M1 genomic library clones containing the wild-type copy of the interrupted gene. One of the selected cosmids, containing a 22-kb genomic insert, was able to complement the N22 mutant for growth on β-myrcene. A 5,370-bp-long sequence spanning the region interrupted by the transposon in the mutant was determined. We identified four open reading frames, named myrA,myrB, myrC, and myrD, which can potentially code for an aldehyde dehydrogenase, an alcohol dehydrogenase, an acyl-coenzyme A (CoA) synthetase, and an enoyl-CoA hydratase, respectively. myrA, myrB, andmyrC are likely organized in an operon, since they are separated by only 19 and 36 nucleotides (nt), respectively, and no promoter-like sequences have been found in these regions. ThemyrD gene starts 224 nt upstream of myrA and is divergently transcribed. The myrB sequence was found to be completely identical to the one flanking the transposon in the mutant. Therefore, we could ascertain that the transposon had been inserted inside the myrB gene, in complete agreement with the accumulation of (E)-2-methyl-6-methylen-2,7-octadien-1-ol by the mutant. Based on sequence and biotransformation data, we propose a pathway for β-myrcene catabolism in Pseudomonas sp. strain M1.


2000 ◽  
Vol 74 (7) ◽  
pp. 3149-3155 ◽  
Author(s):  
Mei Huang ◽  
Dora Chin-Yen Koh ◽  
Li-Juan Weng ◽  
Min-Li Chang ◽  
Yun-Kiam Yap ◽  
...  

ABSTRACT The complete nucleotide sequence of hibiscus chlorotic ringspot virus (HCRSV) was determined. The genomic RNA (gRNA) is 3,911 nucleotides long and has the potential to encode seven viral proteins in the order of 28 (p28), 23 (p23), 81 (p81), 8 (p8), 9 (p9), 38 (p38), and 25 (p25) kDa. Excluding two unique open reading frames (ORFs) encoding p23 and p25, the ORFs encode proteins with high amino acid similarity to those of carmoviruses. In addition to gRNA, two 3′-coterminated subgenomic RNA (sgRNA) species were identified. Full-length cDNA clones derived from gRNA and sgRNA were constructed under the control of a T7 promoter. Both capped and uncapped transcripts derived from the full-length genomic cDNA clone were infectious. In vitro translation and mutagenesis assays confirmed that all the predicted ORFs except the ORF encoding p8 are translatable, and the two novel ORFs (those encoding p23 and p25) may be functionally indispensable for the viral infection cycle. Based on virion morphology and genome organization, we propose that HCRSV be classified as a new member of the genus Carmovirus in familyTombusviridae.


2000 ◽  
Vol 182 (21) ◽  
pp. 6066-6074 ◽  
Author(s):  
Andrew M. Kropinski

ABSTRACT Temperate bacteriophage D3, a member of the virus familySiphoviridae, is responsible for serotype conversion in its host, Pseudomonas aeruginosa. The complete sequence of the double-stranded DNA genome has been determined. The 56,426 bp contains 90 putative open reading frames (ORFs) and four genes specifying tRNAs. The latter are specific for methionine (AUG), glycine (GGA), asparagine (AAC), and threonine (ACA). The tRNAs may function in the translation of certain highly expressed proteins from this relatively AT-rich genome. D3 proteins which exhibited a high degree of sequence similarity to previously characterized phage proteins included the portal, major head, tail, and tail tape measure proteins, endolysin, integrase, helicase, and NinG. The layout of genes was reminiscent of lambdoid phages, with the exception of the placement of the endolysin gene, which parenthetically also lacked a cognate holin. The greatest sequence similarity was found in the morphogenesis genes to coliphages HK022 and HK97. Among the ORFs was discovered the gene encoding the fucosamine O-acetylase, which is in part responsible for the serotype conversion events.


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