Journal Article

<i>In vitro</i> resistance to the CSαβ-type antimicrobial peptide ASABF-[math] is conferred by overexpression of sigma factor <i>sigB</i> in <i>Staphylococcus aureus</i>

Hong Zhang, Kazuya Morikawa, Toshiko Ohta and Yusuke Kato

in Journal of Antimicrobial Chemotherapy

Volume 55, issue 5, pages 686-691
Published in print May 2005 | ISSN: 0305-7453
Published online May 2005 | e-ISSN: 1460-2091 | DOI: http://dx.doi.org/10.1093/jac/dki070
In vitro resistance to the CSαβ-type antimicrobial peptide ASABF-[math] is conferred by overexpression of sigma factor sigB in Staphylococcus aureus

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Objectives: ASABF (Ascaris suum antibacterial factor) is a CSαβ-type antimicrobial peptide isolated from nematodes. ASABF-[math], a member of ASABF, is particularly effective against the Gram-positive pathogen Staphylococcus aureus. In this study, we investigated the role of sigB expression on ASABF-resistance in S. aureus.

Methods: Based on preliminary characterization of the ASABF-resistant strain, Mu50, we speculated that the alternative sigma factor sigB may regulate resistance against antimicrobial peptides. To test this hypothesis, the ASABF susceptibility was compared between NKSB (a sigB-knockout derivative of N315) and its sigB-overexpressing derivative. In addition, similar experiments were carried out for N315ex, a deletion mutant of N315 for SCCmec (Staphylococcus cassette chromosome mec) which contains essential genes for β-lactam resistance.

Results: The sigB-overexpressing NKSB acquired an increased resistance to ASABF-[math] compared with the parent strain. The sigB-induced ASABF-[math] resistance was also observed in N315ex.

Conclusions: The overexpression of sigB confers resistance to the antimicrobial peptide, ASABF-[math]. SCCmec is not essential for this resistance.

Keywords: Caenorhabditis elegans; Ascaris suum; stress response; defensin; antibiotics; CSαβ motif

Journal Article.  4487 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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