Analysis and identification of IS1548 insertion targets in Streptococcus agalactiae

Authors

  • Maud Fléchard,

    Corresponding author
    • Université de Tours, UMR1282 Infectiologie et Santé Publique, Équipe “Bactéries et Risque Materno-Foetal”, Tours, France
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  • Philippe Gilot,

    1. Université de Tours, UMR1282 Infectiologie et Santé Publique, Équipe “Bactéries et Risque Materno-Foetal”, Tours, France
    2. INRA, UMR1282 Infectiologie et Santé Publique, Équipe “Bactéries et Risque Materno-Foetal”, Nouzilly, France
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  • Geneviève Héry-Arnaud,

    1. Université de Tours, UMR1282 Infectiologie et Santé Publique, Équipe “Bactéries et Risque Materno-Foetal”, Tours, France
    2. CHRU de Tours, Service de Bactériologie-Virologie, Tours, France
    Current affiliation:
    1. Laboratoire Universitaire de Biodiversité et Écologie Microbienne (EA 3882), Université Européenne de Bretagne, Université de Brest, Brest, France
    2. Département de Bactériologie-Virologie, Hygiène Hospitalière et Parasitologie-Mycologie, CHRU Brest, Brest, France
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  • Laurent Mereghetti,

    1. Université de Tours, UMR1282 Infectiologie et Santé Publique, Équipe “Bactéries et Risque Materno-Foetal”, Tours, France
    2. CHRU de Tours, Service de Bactériologie-Virologie, Tours, France
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  • Agnès Rosenau

    1. Université de Tours, UMR1282 Infectiologie et Santé Publique, Équipe “Bactéries et Risque Materno-Foetal”, Tours, France
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Correspondence: Maud Fléchard, UMR1282 Infectiologie et Santé Publique, Université de Tours, Faculté de Médecine, boulevard Tonnellé, BP 3223, 37032 Tours, Cedex, France. Tel.:+33 02 47 36 61 93; fax: +33 02 47 47 38 12; e-mail: maud.flechard@voila.fr

Abstract

The prevalence of the insertion sequence IS1548 is strongly linked to clonal complex 19 Streptococcus agalactiae strains associated with neonatal meningitis and endocarditis. We previously reported that IS1548 insertion upstream of lmb is involved in stronger binding of a S. agalactiae meningitic strain to laminin. A few other IS1548 insertion sites were also identified by others. In this study, we analyzed IS1548 described target sites in Sagalactiae and showed that most of them are linked to zinc-responsive genes. Moreover, we identified two not yet described IS1548 insertion sites in the adcRCB operon encoding the main regulator of zinc homeostasis and subunits of a zinc ABC transporter. We also identified two conserved motifs of 8 and 10 bp close to IS1548 insertion sites. These motifs representing potential IS1548 targets were found upstream of several S. agalactiae ORFs. One of these predicted IS1548 targets was validated experimentally, allowing the identification of an IS1548 insertion site upstream of murB in all of the clonal complex 19 strains tested. The possible effects of these insertions on the virulence of the strains are discussed.

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