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The primary sigma factor of Staphylococcus aureus, [[sigma].sup.SA], regulates the transcription of many genes, including several essential genes, in this bacterium via specific recognition of exponential growth phase promoters. In this study, we report the existence of a novel staphylococcal phage G1-derived growth inhibitory polypeptide, referred to as G1ORF67, that interacts with [[sigma].sup.SA] both in vivo and in vitro and regulates its activity. Delineation of the minimal domain of [[sigma].sup.SA] that is required for its interaction with G1ORF67 as amino acids 294 to 360 near the carboxy terminus suggests that the G1 phage-encoded anti-[sigma] factor may occlude the -35 element recognition domain of [[sigma].sup.SA]. AS would be predicted by this hypothesis, the G1ORF67 polypeptide abolished both RNA polymerase core-dependent binding of [[sigma].sup.SA] to DNA and [[sigma].sup.SA]-dependent transcription in vitro. While G1ORF67 profoundly inhibits transcription when expressed in S. aureus cells in mode of action studies, our finding that G1ORF67 was unable to inhibit transcription when expressed in Escherichia coli concurs with its inability to inhibit transcription by the E. coli holoenzyme in vitro. These features demonstrate the selectivity of G1ORF67 for S. aureus RNA polymerase. We predict that G1ORF67 is one of the central polypeptides in the phage G1 strategy to appropriate host RNA polymerase and redirect it to phage reproduction.

A genomic analysis of 18 P. aeruginosa phages, including nine newly sequenced DNA genomes, indicates a tremendous reservoir of proteome diversity, with 55% of open reading frames (ORFs) being novel. Comparative sequence analysis and ORF map organization revealed that most of the phages analyzed displayed little relationship to each other.

Researchers describe the isolation of the gutS gene in E. coli. This gene is induced by selenium and telluride, which are both toxic to living cells in high concentrations.

Sequencing and cloning of an arsenic inducible operon present in the chromosome of Escherichia coli using a lacZ transcriptional gene fusion library shows that this operon is analogous in terms of protein sequence and genetic organization to the plasma induced ars determinant. This ars operon is functionally significant in the detoxification of metalloid in Escherichia coli and its expression can be induced by exposure to sodium arsenite at 5 micro grams/liter. The experimental set up of the cloning and sequencing of an arsenic inducible operon is discussed.

Abstract Background Bacteriophage classification is mainly based on morphological traits and genome characteristics combined with host information and in some cases on phage growth lifestyle. A lack of molecular tools can impede more precise studies on phylogenetic relationships or even a taxonomic classification. The use of methods to analyze genome sequences without the requirement for homology has allowed advances in classification. Results Here, we proposed to use genome sequence signature to characterize bacteriophages and to compare them to their host genome signature in order to obtain host-phage relationships and information on their lifestyle. We analyze the host-phage relationships in the four most representative groups of Caudoviridae, the dsDNA group of phages. We demonstrate that the use of phage genomic signature and its comparison with that of the host allows a grouping of phages and is also able to predict the host-phage relationships (lytic vs. temperate). Conclusions We can thus condense, in relatively simple figures, this phage information dispersed over many publications.

The characteristics of ygaVP genes of Escherichia coli that are formed by fusion of tributylin (TBT) luxAB are examined. The results show that a TBT-activated promoter is located upstream of ygaVP and is constitutive in a ygaVP mutant, indicating that YgaV is an autoregulated TBT-inducible repressor.

Operons encoding homologous arsenic-resistance determinants (ars) have been found in Gram-positive and Gram-negative bacterial plasmids. A Pseudomonas aeruginosa chromosomal ars operon homologue has been identified through cloning and complementation of an E. coli ars mutant, containing three potential ORFs. Operon expression was induced by arsenite at the mRNA level, and DNA sequences homlogous with the operon were detected in some Pseudomonas species.

Ocean acidification may stimulate primary production through increased availability of inorganic carbon in the photic zone, which may in turn change the biogenic flux of dissolved organic carbon ( DOC) and the growth potential of heterotrophic bacteria. To investigate the effects of ocean acidification on marine bacterial assemblages, a two-by-three factorial mescosom experiment was conducted using surface sea water from the East Greenland Current in Fram Strait. Pyrosequencing of the V1- V2 region of bacterial 16S ribosomal RNA genes was used to investigate differences in the endpoint (Day 9) composition of bacterial assemblages in mineral nutrient-replete mesocosms amended with glucose (0 μ m, 5.3 μ m and 15.9 μ m) under ambient (250 μatm) or acidified (400 μatm) partial pressures of CO2 ( p CO2). All mesocosms showed low richness and diversity by Chao1 estimator and Shannon index, respectively, with general dominance by Gammaproteobacteria and Flavobacteria. Nonmetric multidimensional scaling analysis and two-way analysis of variance of the Jaccard dissimilarity matrix (97% similarity cut-off) demonstrated that the significant community shift between 0 μ m and 15.9 μ m glucose addition at 250 μatm p CO2 was eliminated at 400 μatm p CO2. These results suggest that the response potential of marine bacteria to DOC input may be altered under acidified conditions. [ABSTRACT FROM AUTHOR]

Background: Bacteriophage classification is mainly based on morphological traits and genome characteristics combined with host information and in some cases on phage growth lifestyle. A lack of molecular tools can impede more precise studies on phylogenetic relationships or even a taxonomic classification. The use of methods to analyze genome sequences without the requirement for homology has allowed advances in classification. Results: Here, we proposed to use genome sequence signature to characterize bacteriophages and to compare them to their host genome signature in order to obtain host-phage relationships and information on their lifestyle. We analyze the host-phage relationships in the four most representative groups of Caudoviridae, the dsDNA group of phages. We demonstrate that the use of phage genomic signature and its comparison with that of the host allows a grouping of phages and is also able to predict the host-phage relationships (lytic vs. temperate). Conclusions: We can thus condense, in relatively simple figures, this phage information dispersed over many publications. [ABSTRACT FROM AUTHOR]

Over evolutionary time bacteriophages have developed unique proteins that arrest critical cellular processes to commit bacterial host metabolism to phage reproduction. Here, we apply this concept of phage-mediated bacterial growth inhibition to antibiotic discovery. We sequenced 26 Staphylococcus aureus phages and identified 31 novel polypeptide families that inhibited growth upon expression in S. aureus. The cellular targets for some of these polypeptides were identified and several were shown to be essential components of the host DNA replication and transcription machineries. The interaction between a prototypic pair, ORF104 of phage 77 and DnaI, the putative helicase loader of S. aureus, was then used to screen for small molecule inhibitors. Several compounds were subsequently found to inhibit both bacterial growth and DNA synthesis. Our results suggest that mimicking the growth-inhibitory effect of phage polypeptides by a chemical compound, coupled with the plethora of phages on earth, will yield new antibiotics to combat infectious diseases. [ABSTRACT FROM AUTHOR]