Horizontal Transfer of
 parC
 and
 gyrA
 in Fluoroquinolone-Resistant Clinical Isolates of
 Streptococcus pneumoniae

Ferrándiz, Marı́a José; Fenoll, Asunción; Liñares, Josefina; Campa, Adela G. de la

doi:10.1128/aac.44.4.840-847.2000

Cited by 86 publications

(65 citation statements)

References 53 publications

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“…The region contained the entire length of the putative gyrA gene (84% identity to gyrA of S. pneumoniae [AF170993]) (8) and one incomplete ORF starting 7 bp downstream of gyrA. The deduced amino acid sequence of the ORF was found to be homologous to the sortase of S. gordonii (described in detail below), and the gene was tentatively designated srtA.…”

Section: Resultsmentioning

confidence: 99%

Characterization of Streptococcus suis Genes Encoding Proteins Homologous to Sortase of Gram-Positive Bacteria

et al. 2002

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Many surface proteins which are covalently linked to the cell wall of gram-positive bacteria have a consensus C-terminal motif, Leu-Pro-X-Thr-Gly (LPXTG). This sequence is cleaved, and the processed protein is attached to an amino group of a cross-bridge in the peptideglycan by a specific enzyme called sortase. Using the type strain of Streptococcus suis, NCTC 10234, we found five genes encoding proteins that were homologous to sortases of other bacteria and determined the nucleotide sequences of the genetic regions. One gene, designated srtA, was linked to gyrA, as were the sortase and sortase-like genes of other streptococci. Three genes, designated srtB, srtC, and srtD, were tandemly clustered in a different location, where there were three segments of directly repeated sequences of approximately 110 bp in close vicinity. The remaining gene, designated srtE, was located separately on the chromosome with a pseudogene which may encode a transposase. The deduced amino acid sequences of the five Srt proteins showed 18 to 31% identity with the sortases of Streptococcus gordonii and Staphylococcus aureus, except that SrtA of S. suis had 65% identity with that of S. gordonii. Isogenic mutants deficient for srtA, srtBCD, or srtE were generated by allelic exchanges. The protein fraction which was released from partially purified cell walls by digestion with N-acetylmuramidase was profiled by two-dimensional gel electrophoresis. More than 15 of the protein spots were missing in the profile of the srtA mutant compared with that of the parent strain, and this phenotype was completely complemented by srtA cloned from S. suis. Four genes encoding proteins corresponding to such spots were identified and sequenced. The deduced translational products of the four genes possessed the LPXTG motif in their C-terminal regions. On the other hand, the protein spots that were missing in the srtA mutant appeared in the profiles of the srtBCD and srtE mutants. These results provide evidence that the cell wall sorting system involving srtA is also present in S. suis.Many cell wall surface proteins of gram-positive bacteria are covalently anchored to the cell wall by a mechanism requiring a C-terminal anchoring motif, which consists of a conserved amino acid sequence, Leu-Pro-X-Thr-Gly (LPXTG, where X is any amino acid), followed by a hydrophobic domain and, in most cases, a tail of positively charged residues (11, 47). A series of elegant studies by Schneewind and his colleagues (32,35,45,46) have determined the function of a membranelocalized cysteine protease, named sortase, using protein A of Staphylococcus aureus as the model. Sortase specifically cleaves the LPXTG sequence in protein A between the threonine and glycine residues and catalyzes the transfer of the processed protein to the free amino group of pentaglycine cross-bridges in the staphylococcal peptidoglycan. Thus, sortase appears to be a multifunctional protease-transpeptidase (58, 59).Computational searches of complete and preliminary genome sequence data have revealed t...

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Section: Resultsmentioning

confidence: 99%

Characterization of Streptococcus suis Genes Encoding Proteins Homologous to Sortase of Gram-Positive Bacteria

et al. 2002

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“…Genetic transformation is envisaged as the main mechanism of horizontal gene transfer among the mitis group streptococci, leading to rapid spread of ␤-lactam (13) and fluoroquinolone (18) resistance, whereas the contribution of phages, either lytic or temperate, to the dissemination of clinically relevant genes has not been so well established. Although some clues on the recombination between the S. pneumoniae lytA gene and those VOL.…”

Section: Discussionmentioning

confidence: 99%

Characterization of LytA-LikeN-Acetylmuramoyl-l-Alanine Amidases from Two NewStreptococcus mitisBacteriophages Provides Insights into the Properties of the Major Pneumococcal Autolysin

2004

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Two new temperate bacteriophages exhibiting a Myoviridae (B6) and a Siphoviridae (HER) morphology have been isolated from Streptococcus mitis strains B6 and HER 1055, respectively, and partially characterized. The lytic phage genes were overexpressed in Escherichia coli, and their encoded proteins were purified. The lytA HER and lytA B6 genes are very similar (87% identity) and appeared to belong to the group of the so-called typical LytA amidases (atypical LytA displays a characteristic two-amino-acid deletion signature). although they exhibited several differential biochemical properties with respect to the pneumococcal LytA, e.g., they were inhibited in vitro by sodium deoxycholate and showed a more acidic pH for optimal activity. However, and in sharp contrast with the pneumococcal LytA, a short dialysis of LytA HER or LytA B6 resulted in reversible deconversion to the low-activity state (E-form) of the fully active phage amidases (C-form). Comparison of the amino acid sequences of LytA HER and LytA B6 with that of the pneumococcal amidase suggested that Val 317 might be responsible for at least some of the peculiar properties of S. mitis phage enzymes. Site-directed mutagenesis that changed Val 317 in the pneumococcal LytA amidase to a Thr residue (characteristic of LytA B6 and LytA HER ) produced a fully active pneumococcal enzyme that differs from the parental one only in that the mutant amidase can reversibly recover the low-activity E-form upon dialysis. This is the first report showing that a single amino acid residue is involved in the conversion process of the major S. pneumoniae autolysin. Our results also showed that some lysogenic S. mitis strains possess a lytA-like gene, something that was previously thought to be exclusive to Streptococcus pneumoniae. Moreover, the newly discovered phage lysins constitute a missing link between the typical and atypical pneumococcal amidases known previously.

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“…Southern blot identification of strains. Restriction fragments carrying lytA and ply (pneumolysin) DNA probes and PCR products carrying the ant probe (a homolog of genes encoding aminoglycoside adenylyltransferases) were obtained as described previously (14,23). Probes were labeled with a Phototope-Star detection kit (New England Biolabs).…”

Section: Methodsmentioning

confidence: 99%

Molecular Characterization of Disease-Associated Streptococci of the Mitis Group That Are Optochin Susceptible

Balsalobre¹,

Hernández-Madrid²,

Llull

et al. 2006

J Clin Microbiol

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Eight optochin-susceptible (Opt s ) alpha-hemolytic (viridans) streptococcus isolates were characterized at the molecular level. These isolates showed phenotypic characteristics typical of both viridans streptococci and Streptococcus pneumoniae. Comparison of the sequence of housekeeping genes from these isolates with those of S. pneumoniae, Streptococcus mitis, Streptococcus oralis, and Streptococcus pseudopneumoniae suggested that the Opt s isolates corresponded to streptococci of the mitis group. Besides, the Opt s streptococci were negative by a Gen-Probe AccuProbe pneumococcus test and hybridized with specific pneumococcal probes (lytA and ply) but also with ant, a gene not present in most S. pneumoniae strains. Moreover, the isolates were insoluble in 1% sodium deoxycholate but completely dissolved in 0.1% deoxycholate. Sequence analysis of the lytA gene revealed that the Opt s streptococci carried lytA alleles characteristic of those present in nonpneumococcal streptococci of the mitis group. The determination of the partial nucleotide sequence embracing the atp operon encoding the F o F 1 H ؉ -ATPase indicated that the optochin susceptibility of the isolates was due to the acquisition of atpC, atpA, and part of atpB from S. pneumoniae by horizontal gene transfer.

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Horizontal Transfer of parC and gyrA in Fluoroquinolone-Resistant Clinical Isolates of Streptococcus pneumoniae

Cited by 86 publications

References 53 publications

Characterization of Streptococcus suis Genes Encoding Proteins Homologous to Sortase of Gram-Positive Bacteria

Characterization of Streptococcus suis Genes Encoding Proteins Homologous to Sortase of Gram-Positive Bacteria

Characterization of LytA-LikeN-Acetylmuramoyl-l-Alanine Amidases from Two NewStreptococcus mitisBacteriophages Provides Insights into the Properties of the Major Pneumococcal Autolysin

Molecular Characterization of Disease-Associated Streptococci of the Mitis Group That Are Optochin Susceptible

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