Abstract
Streptococcus (S.) suis is a zoonotic pathogen causing septicemia and meningitis in pigs and humans. During infection S. suis must metabolically adapt to extremely diverse environments of the host. CcpA and the FNR family of bacterial transcriptional regulators are important for metabolic gene regulation in various bacteria. The role of CcpA in S. suis is well defined, but the function of the FNR-like protein of S. suis, FlpS, is yet unknown. Transcriptome analyses of wild-type S. suis and a flpS mutant strain suggested that FlpS is involved in the regulation of the central carbon, arginine degradation and nucleotide metabolism. However, isotopologue profiling revealed no substantial changes in the core carbon and amino acid de novo biosynthesis. FlpS was essential for the induction of the arcABC operon of the arginine degrading pathway under aerobic and anaerobic conditions. The arcABC-inducing activity of FlpS could be associated with the level of free oxygen in the culture medium. FlpS was necessary for arcABC-dependent intracellular bacterial survival but redundant in a mice infection model. Based on these results, we propose that the core function of S. suis FlpS is the oxygen-dependent activation of the arginine deiminase system.
Highlights
Streptococcus suis is one of the most important porcine pathogens causing meningitis, septicemia, and polyarthritis
FNR-like protein of S. suis (FlpS) is Involved in the Regulation of the arcABC Operon and Metabolic Genes
In order to dissect the role of FlpS in S. suis, we first determined the FlpS regulon
Summary
Streptococcus suis is one of the most important porcine pathogens causing meningitis, septicemia, and polyarthritis. S. suis infections lead to high financial losses in the swine-producing industry worldwide [1]. S. suis is considered a neglected zoonotic pathogen that can cause pathologies such as meningitis and septicemia, as well as a streptococcal toxic shock-like syndrome in humans [2,3,4,5]. Little is known about the pathogenicity of S. suis in porcine as well as human infections. What is known about the antiphagocytic polysaccharide capsule and several proposed virulence-associated factors [6], elucidation of global regulatory networks that coordinate an efficient adaptation to changing metabolic and environmental stimuli, is a prerequisite for understanding the pathogenesis of S. suis infections.
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