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Natural Atypical Listeria innocua Strains with Listeria monocytogenes Pathogenicity Island 1 Genes. J. Johnson, 2004.Identification of bona fide Listeria isolates into the six species of the genus normally requires only a few tests . Aberrant isolates do occur, but even then only one or two extra confirmatory tests are generally needed for identification to species level . We have discovered a hemolytic-positive, rhamnose and xylose fermentation-negative Listeria strain with surprising recalcitrance to identification to the species level due to contradictory results in standard confirmatory tests . The issue had to be resolved by using total DNA-DNA hybridization testing and then confirmed by further specific PCR-based tests including a Listeria microarray assay . The results show that this isolate is indeed a novel one . Its discovery provides the first fully documented instance of a hemolytic Listeria innocua strain . This species, by definition, is typically nonhemolytic . The L . innocua isolate contains all the members of the PrfA-regulated virulence gene cluster (Listeria pathogenicity island 1) of L . monocytogenes . It is avirulent in the mouse pathogenicity test . Avirulence is likely at least partly due to the absence of the L . monocytogenes-specific allele of iap, as well as the absence of inlA, inlB, inlC, and daaA . At least two of the virulence cluster genes, hly and plcA, which encode the L . monocytogenes hemolysin (listeriolysin O) and inositol-specific phospholipase C, respectively, are phenotypically expressed in this L . innocua strain . The detection by PCR assays of specific L . innocua genes (lin0198, lin0372, lin0419, lin0558, lin1068, lin1073, lin1074, lin2454, and lin2693) and noncoding intergenic regions (lin0454-lin0455 and nadA-lin2134) in the strain is consistent with its L . innocua DNA-DNA hybridization identity . Additional distinctly different hemolytic L . innocua strains were also studied . Vibrio cholerae Phage K139: Complete Genome Sequence and Comparative Genomics of Related Phages. Dagmar Kapfhammer, 2002.In this report, we characterize the complete genome sequence of the temperate phage K139, which morphologically belongs to the Myoviridae phage family (P2 and 186) . The prophage genome consists of 33,106 bp, and the overall GC content is 48.9% . Forty-four open reading frames were identified . Homology analysis and motif search were used to assign possible functions for the genes, revealing a close relationship to P2-like phages . By Southern blot screening of a Vibrio cholerae strain collection, two highly K139-related phage sequences were detected in non-O1, non-O139 strains . Combinatorial PCR analysis revealed almost identical genome organizations . One region of variable gene content was identified and sequenced . Additionally, the tail fiber genes were analyzed, leading to the identification of putative host-specific sequence variations . Furthermore, a K139-encoded Dam methyltransferase was characterized . Crystal Structure of the Hyperthermophilic Archaeal DNA-Binding Protein Sso10b2 at a Resolution of 1.85 Angstroms. Chia-Cheng Chou, 2003.The crystal structure of a small, basic DNA binding protein, Sso10b2, from the thermoacidophilic archaeon Sulfolobus solfataricus was determined by the Zn multiwavelength anomalous diffraction method and refined to 1.85 Å resolution . The 89-amino-acid protein adopts a ß  ßßß topology . The structure is similar to that of Sso10b1 (also called Alba) from the same organism . However, Sso10b2 contains an arginine-rich loop RDRRR motif, which may play an important role in nucleic acid binding . There are two independent Sso10b2 proteins in the asymmetric unit, and a plausible stable dimer could be deduced from the crystal structure . Topology comparison revealed that Sso10b2 is similar to several RNA-binding proteins, including IF3-C, YhhP, and DNase I . Models of the Sso10b2 dimer bound to either B-DNA or A-DNA have been constructed .
Habitat-Specific Diversity of Borrelia burgdorferi Sensu Lato in Europe, Exemplified by Data from Latvia. Susanne Etti, 2003.The distribution of Borrelia burgdorferi sensu lato genospecies in questing Ixodes ricinus ticks from ecologically distinct habitats in Latvia was analyzed . A significant variation in the frequency of the genospecies across sites was observed, pointing to the importance of the host community in the ecology of Lyme borreliosis .
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