1,721,098 research outputs found
Allelic Variation in the highly polymorphic pspC locus of Streptococcus pneumoniae
No full textPspC, also called SpsA, CbpA, PbcA, and Hic, is a surface protein of Streptococcus pneumoniae studied for its antigenic properties, its capability to bind secretory IgA, C3 and complement factor H, and its activity as an adhesin. In this work we characterized the pspC locus of 43 pneumococcal strains by DNA sequencing of PCR fragments. Using PCR primers designed on two unrelated open reading frames, flanking the pspC locus, it was possible to amplify the pspC locus of each of the 43 strains of S. pneumoniae. In 37 out of 43 strains there was a single copy of the pspC gene, while two tandem copies of pspC were found in the other six strains. The sequence of the pspC locus was different in each of the 43 strains. Insertion sequences were found in the pspC locus of 11 out of 43 strains. Analysis of the deduced amino acid sequence of the PspC variants showed a common organization of the molecules: (i) a 37 amino acid leader peptide which is conserved in all proteins, (ii) an N-terminal portion which is essentially alpha-helical, and is the result of assembly of eight major sequence blocks, (iii) a proline-rich region, and (iv) a C-terminal anchor responsible for the cell surface attachment. By sequence comparison we identified 11 major groups of PspC proteins. Proteins within one group displayed only minor variations of the amino acid sequence. An unexpected finding was that PspC variants could differ in the anchor sequence. While 32 of the PspC proteins displayed the typical choline binding domain of pneumococcal surface proteins, 17 other PspCs showed the LPXTG motif, which is typical of surface proteins of other gram-positive bacteria. This major difference in the anchor region was also observed in the adjacent proline-rich regions which differed considerably in size and composition
Sistema binario di sonde fluorescenti per PCR real-time, metodo diagnostico e kit relativo
Full text linkL' Invenzione concerne un sistema binario di sonde delle quali almeno una presenta geometria circolare, ad elevata specificità, da utilizzare nella tecnica della PCR real-time come kit diagnostico per la rilevazione specifica di sequenze geniche e la discriminazione di specie microbiche , quali ad esempio , la sequenza IS 6110 di Mycobacterium tuberculosis
DNA probe for identification of Streptococcus pneumoniae
No full textA total of 287 clinical isolates of Streptococcus pneumoniae (pneumococcus) were tested for their ability to undergo autolysis when treated with sodium deoxycholate. The test was positive for all but one isolate, strain DOC-1. This autolysis required the activity of an enzyme which is unique and characteristic of S. pneumoniae: a choline-dependent N-acetylmuramoyl-L-alanine amidase, the gene product of the lytA gene. We used lytA as a DNA probe to test the distribution of the autolysin gene among clinical isolates of S. pneumoniae. In dot blot hybridization experiments our probe reacted with the DNA of 60 of 60 strains tested, including the autolysis-deficient clinical isolate DOC-1. No hybridization occurred when strains of Streptococcus sanguis, Streptococcus mutans, Streptococcus pyogenes, Streptococcus (Enterococcus) faecalis, Streptococcus (Enterococcus) faecium, Streptococcus agalactiae, and Streptococcus bovis were tested. The lytA gene appears to be an ideal candidate for use as a DNA probe for the identification of S. pneumoniae
A host-vector system for heterologous gene expression in Streptococcus gordonii.
No full textWe have developed a host-vector system for heterologous expression in Streptococcus gordonii (Sg) Challis (formerly Streptococcus sanguis), a commensal bacterium of the human oral cavity. The system is based on (i) integration of plasmid insertion vectors into the chromosome of specially engineered recipient hosts, and (ii) the use of the M6-protein-encoding gene (emm6) as a partner for construction of translational gene fusions. M6 is a streptococcal surface protein already proven useful as a fusion partner for the delivery of foreign antigens to the surface of Sg [Pozzi et al., Infect. Immun. 60 (1992) 1902-1907]. Insertion vectors carry a drug-resistance marker, different portions of emm6 and a multiple cloning site to allow construction of a variety of emm6-based fusions. Upon transformation of a recipient host with an insertion vector, 100% of transformants acquire both the drug-resistance marker and the capacity of displaying the M6 molecule on the cell surface. Chromosomal integration occurred at high frequency in recipient host GP1221. Transformation with 1 microgram of insertion vector DNA yielded 8.1 X 10(5) transformants per ml of competent cells
Omega-6001-mediated conjugative mobilization of the cloned M6 protein gene to the chromosomes of different strains of Streptococcus pyogenes
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Expression of M6 protein gene of Streptococcus pyogenes in Streptococcus gordonii after chromosomal integration and transcriptional fusion
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