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Front Microbiol. 2017 Apr 26;8:724. doi: 10.3389/fmicb.2017.00724. eCollection 2017.

Identification of Genes Controlled by the Essential YycFG Two-Component System Reveals a Role for Biofilm Modulation in Staphylococcus epidermidis.

Author information

1
Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Department of Medical Microbiology and Parasitology, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Fudan UniversityShanghai, China.
2
Key Laboratory of Medical Molecular Virology, Huashan Hospital, Shanghai Medical College of Fudan UniversityShanghai, China.
3
Klinikum Nürnberg Medical School GmbH, Research Department, Paracelsus Medical UniversityNuremberg, Germany.
4
Department of Microbial Genetics, Faculty of Science, Interfaculty Institute of Microbiology and Infection Medicine Tübingen, University of TübingenTübingen, Germany.
5
Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins UniversityBaltimore, MD, USA.

Abstract

Biofilms play a crucial role in the pathogenicity of Staphylococcus epidermidis, while little is known about whether the essential YycFG two-component signal transduction system (TCS) is involved in biofilm formation. We used antisense RNA (asRNA) to silence the yycFG TCS in order to study its regulatory functions in S. epidermidis. Strain 1457 expressing asRNA yycF exhibited a significant delay (~4-5 h) in entry to log phase, which was partially complemented by overexpressing ssaA. The expression of asRNA yycF and asRNA yycG resulted in a 68 and 50% decrease in biofilm formation at 6 h, respectively, while they had no significant inhibitory effect on 12 h biofilm formation. The expression of asRNA yycF led to a ~5-fold increase in polysaccharide intercellular adhesion (PIA) production, but it did not affect the expression of accumulation-associated protein (Aap) or the release of extracellular DNA. Consistently, quantitative real-time PCR showed that silencing yycF resulted in an increased transcription of biofilm-related genes, including icaA, arlR, sarA, sarX, and sbp. An in silico search of the YycF regulon for the conserved YycF recognition pattern and a modified motif in S. epidermidis, along with additional gel shift and DNase I footprinting assays, showed that arlR, sarA, sarX, and icaA are directly regulated by YycF. Our data suggests that YycFG modulates S. epidermidis biofilm formation in an ica-dependent manner.

KEYWORDS:

Staphylococcus epidermidis; YycFG; antisense RNA; biofilm; two-component signal transduction system

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