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The Acidic Nature of the CcmG Redox-Active Center Is Important for Cytochrome c Maturation in Escherichia coli. Melissa A. Edeling, 2004.Cytochrome c biogenesis in Escherichia coli is a complex process requiring at least eight genes (ccmABCDEFGH) . One of these genes, ccmG, encodes a thioredoxin-like protein with unusually specific redox activity . Here, we investigate the basis for CcmG function and demonstrate the importance of acidic residues surrounding the redox-active center . Genetic Variability of Yersinia pestis Isolates as Predicted by PCR-Based IS100 Genotyping and Analysis of Structural Genes Encoding Glycerol-3-Phosphate Dehydrogenase (glpD). Vladimir L. Motin, 2002.A PCR-based genotyping system that detects divergence of IS100 locations within the Yersinia pestis genome was used to characterize a large collection of isolates of different biovars and geographical origins . Using sequences derived from the glycerol-negative biovar orientalis strain CO92, a set of 27 locus-specific primers was designed to amplify fragments between the end of IS100 and its neighboring gene . Geographically diverse members of the orientalis biovar formed a homogeneous group with identical genotype with the exception of strains isolated in Indochina . In contrast, strains belonging to the glycerol-positive biovar antiqua showed a variety of fingerprinting profiles . Moreover, strains of the biovar medievalis (also glycerol positive) clustered together with the antiqua isolates originated from Southeast Asia, suggesting their close phylogenetic relationships . Interestingly, a Manchurian biovar antiqua strain Nicholisk 51 displayed a genotyping pattern typical of biovar orientalis isolates . Analysis of the glycerol pathway in Y . pestis suggested that a 93-bp deletion within the glpD gene encoding aerobic glycerol-3-phosphate dehydrogenase might account for the glycerol-negative phenotype of the orientalis biovar . The glpD gene of strain Nicholisk 51 did not possess this deletion, although it contained two nucleotide substitutions characteristic of the glpD version found exclusively in biovar orientalis strains . To account for this close relationship between biovar orientalis strains and the antiqua Nicholisk 51 isolate, we postulate that the latter represents a variant of this biovar with restored ability to ferment glycerol . The fact that such a genetic lesion might be repaired as part of the natural evolutionary process suggests the existence of genetic exchange between different Yersinia strains in nature . The relevance of this observation on the emergence of epidemic Y . pestis strains is discussed . Gamma-Proteobacteria Aquicella lusitana gen . nov., sp . nov., and Aquicella siphonis sp . nov . Infect Protozoa and Require Activated Charcoal for Growth in Laboratory Media. Paula Santos, 2003.Several isolates, belonging to two new species of the same novel genus of gamma-proteobacteria, were recovered from drilled well (borehole) and spa water at São Gemil in central Portugal . These organisms are phylogenetically most closely related to the strictly intracellular uncultured species of the genus Rickettsiella, which cause disease in arthropods, and to the facultatively intracellular species of the genus Legionella, some of which cause Legionnaires' disease and Pontiac fever . The São Gemil strains grew only on media containing charcoal, as is also true of the species of the genus Legionella . Unlike the vast majority of Legionella isolates, the new isolates did not require L-cysteine or ferric pyrophosphate for growth but like the legionellae had an absolute requirement for  -ketoglutarate . Strains SGT-39T and SGT-56 grew consistently between 30 and 43°C, while strains SGT-108T and SGT-109 grew between 30 and 40°C . The pH ranges for growth of these organisms were surprisingly narrow: strains SGT-39T and SGT-56 grew between pH 6.3 and 7.3, while strains SGT-108T and SGT-109 grew between pH 6.3 and 7.0 . Both organisms proliferated in the amoeba Hartmannella vermiformis but did not grow in U937 human cells . Based on 16S rRNA gene sequence analysis and physiological, biochemical, and chemical analysis we describe two new species of one novel genus; one species is represented by strain SGT-39T, for which we propose the name Aquicella lusitana, while strain SGT-108T represents a second species of the same genus, for which we propose the name Aquicella siphonis .
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