SummaryWe studied the cytological and biochemical properties of the FtsA protein of Streptococcus pneumoniae . FtsA is a widespread bacterial cell division protein that belongs to the actin superfamily. In Escherichia coli and Bacillus subtilis , FtsA localizes to the septal ring after FtsZ, but its exact role in septation is not known. In S. pneumoniae , we found that, during exponential growth, the protein localizes to the nascent septa, at the equatorial zones of the dividing cells, where an average of 2200 FtsA molecules per cell are present. Likewise, FtsZ was found to localize with the same pattern and to be present at an average of 3000 molecules per cell. Consistent with the colocalization, FtsA was found to interact with FtsZ and with itself. Purified FtsA is able to bind several nucleotides, the affinity being highest for adenosine triphosphate (ATP), and lower for other triphosphates and diphosphates. The protein polymerizes in vitro , in a nucleotide-dependent manner, forming long corkscrew-like helixes, composed of 2 + 2 paired protofilaments. No nucleotide hydrolytic activity was detected. Consistent with the absence of an ATPase activity, the polymers are highly stable and not dynamic. These results suggest that the FtsA protein could also polymerize in vivo and the polymers participate in septation.
In total 34 strains of Gardnerella vaginalis were analyzed with various molecular techniques in order to find the possibility of dividing this single species into different genotypes. Classical ribotyping, PCR‐ribotyping and restriction analysis of 16S–23S rRNA intergenic spacer sequences were all unsuccessful in genotype differentiation of these bacteria. Only amplified ribosomal DNA restriction analysis (ARDRA) was suitable in recognizing different G. vaginalis genotypes. At least 3–4 genotypes were identified with different restriction enzymes, some of which showed a prevalent distribution in certain of the centers from which they were collected. Although in this study no correlation was found between bacterial vaginosis and any of the genotypes identified, the ARDRA method could prove to be a useful tool for studying the etiopathology and epidemiology of G. vaginalis.
An original compound, named karalicin, was isolated from a fermentation broth of the Pseudomonas fluorescens/putida strain SS-3 (CCM4430). Production, physico-chemical properties and structure elucidation are described.
Twenty-five high-level gentamicin resistant (HLGR) Enterococcus faecalis strains were isolated from three different University laboratories in Italy. The resistant strains were variously distributed in the three centers with percentages of prevalence ranging from about 3% up to 14%. Almost all strains shared high-level resistance to streptomycin (23 out of 25). Ribotyping and restriction analysis of the 16S-23S rRNA intergenic spacer sequences were used to genetically differentiate the various strains and to study their spreading in the university hospitals serviced by the three laboratories. At least three ribotypes were identified, which showed a peculiar distribution in the various centers. Only the ribotype B was isolated from the University of Padua. In Cagliari, most strains belonged to ribotype A (4/6), whereas in Genoa there was an equal distribution of the ribotypes A and B. A clonal spreading of some HLGR strains is suggested by these findings. The restriction analysis of the 16S-23S rRNA intergenic-spacer sequences gave comparable results with classical ribotyping and, in addition, was quicker and easier to perform than the latter.
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