Staphylococcus aureus AI-2 Quorum Sensing Associates with the KdpDE Two-Component System To Regulate Capsular Polysaccharide Synthesis and Virulence

Abstract

Autoinducer 2 (AI-2) is widely recognized as a signal molecule for intra-and interspecies communication inGram-negative bacteria, but its signaling function in Gram-positive bacteria, especially in Staphylococcus aureus, remains obscure. Here we reveal the role of LuxS in the regulation of capsular polysaccharide synthesis in S. aureus NCTC8325 and show that AI-2 can regulate gene expression and is involved in some physiological activities in S. aureus as a signaling molecule. Inactivation of luxS in S. aureus NCTC8325 resulted in higher levels of transcription of capsular polysaccharide synthesis genes. The survival rate of the luxS mutant was higher than that of the wild type in both human blood and U937 macrophages. In comparison to the luxS mutant, a culture supplemented with chemically synthesized 4,5-dihydroxy-2,3-pentanedione (DPD), the AI-2 precursor molecule, restored all the parental phenotypes, suggesting that AI-2 has a signaling function in S. aureus. Furthermore, we demonstrated that the LuxS/AI-2 signaling system regulates capsular polysaccharide production via a two-component system, KdpDE, whose function has not yet been clarified in S. aureus. This regulation occurred via the phosphorylation of KdpE binding to the cap promoter.Quorum sensing (QS) is a cell-cell communication mechanism in which bacteria secrete and sense small diffusible molecules called autoinducers (AIs) to coordinate social activities, such as bioluminescence, biofilm formation, swarming behavior, antibiotic production, and virulence factor secretion (7,23,38,59). Many QS mechanisms have evolved among bacteria. In general, Gram-negative bacteria use acylated homoserine lactones (AHLs) as AIs, and Gram-positive bacteria use oligopeptide AIs, which act through two-component phosphorelay cascades. Studies have shown that one QS mechanism is shared by both Gram-positive and Gram-negative bacteria and involves the production of autoinducer 2 (AI-2) (4, 38, 59, 60), which is synthesized by the LuxS enzyme in a metabolic pathway known as the activated methyl cycle (50,57,61). AI-2 is not a single compound but a family of interconverting compounds derived from 4,5-dihydroxy-2,3-pentanedione (DPD), which cyclizes spontaneously to form two epimeric furanoses, (2R,4S)-and (2S,4S)-2,4-dihydroxy-2-methyldihydrofuran-3-one (R-and S-DHMF), respectively. Hydration of R-and S-DHMF produces (2R, 4S)-and (2S, 4S)-2-methyl-2,3,3,4-tetrahydroxytetrahydrofuran (R-and S-THMF), respectively (40). In contrast to the other autoinducers that are usually involved in intraspecies communication, AI-2 is widely present in bacteria, leading to the suggestion that it is a universal language for interspecies communication (50,64).The LuxS/AI-2 system is a more recently described QS system which was first identified in Vibrio harveyi, where it functions as part of a complex multilayered QS system to regulate bioluminescence (9, 10). LuxS plays a metabolic role in the activated methyl cycle, and one molecule of DPD is formed as a by-product every one cycle. Thi...

MsaB activates capsule production at the transcription level in Staphylococcus aureus

“…Several DNA-binding proteins have been shown to directly interact with the cap promoter region, but only one regulator, RbsR, has been shown to directly interact with the 10 bp inverted repeat (Zhao et al, 2010;Majerczyk et al, 2010;Sun et al, 2012;Ding et al, 2014;Jutras et al, 2013;Lei & Lee, 2015). We investigated the regulatory relationship between the msaABCR and cap operons by testing whether the putative DNA-binding protein, MsaB, interacts with the cap promoter, using a ChIP assay (Fig.…”

“…Additionally, several regulatory proteins have been shown to bind to the promoter region of the cap operon. These include the twocomponent systems AirSR, KdpDE and SpoVG, as well as nutrient-sensing regulatory proteins CcpE and CodY (Zhao et al, 2010;Majerczyk et al, 2010;Sun et al, 2012;Ding et al, 2014;Jutras et al, 2013). CodY is the best-studied cap regulatory protein and has been shown to sense the availability of nutrients, such as branchedchain amino acids and GTP, during the different phases of bacterial growth.…”

Inhibición de la expresión del sistema agr de Staphylococcus aureus resistente a meticilina mediante el uso de polifenoles totales de hojas de aguacate mexicano (Persea americana var. drymifolia)

“…Expresión de los genes agrA y rnaIII de las cepas de MRSA tratadas con polifenoles totales Para determinar el efecto de los polifenoles sobre el SPQ Agr/AIP de MRSA fueron medidos los niveles de expresión de los genes específicos de los operones P2 y P3. Por una parte, para medir la expresión del operón P2, fue seleccionado el gen agrA y su nivel de expresión fue comparado contra el gen constitutivo 16S (Zhao et al, 2010). Los resultados obtenidos muestran una disminución en la expresión mediada por los polifenoles totales del cultivar María Elena (p<0.001) que va desde el 56% en la cepa de MRSA asociada a infecciones intrahospitalarias (ATCC 33592) hasta el 74% en la cepa μ3, la cual presenta también resistencia intermedia a vancomicina (Figura 2).…”

“…De igual manera, fueron medidos los niveles de expresión del operón P3, para tal efecto, fue utilizado el gen rnaIII, en el cual se encuentra incluido una parte del gen hld mismo que codifica para la δ hemolisina y que está encargado de la expresión de múltiples factores de virulencia, adhesión y supervivencia de la bacteria (Zhao et al, 2010). De manera similar a lo obtenido con la expresión del gen agrA fue obtenida una reducción en los niveles de expresión del operón P3, sin embargo, pese a ser un resultado estadísticamente significativo (p<0.001), estos obtuvieron un índice menor a los obtenidos con el gen agrA.…”

The Staphylococcus aureus Autoinducer-2 Synthase LuxS Is Regulated by Ser/Thr Phosphorylation

“…The LuxS/AI-2 system in Staphylococcus aureus, a highly adaptable Gram-positive bacterium responsible for numerous clinical infections, has been analyzed in detail (13,14,28). Moreover, the emergence of antibiotic resistance has become a serious concern, especially due to methicillin-resistant S. aureus (MRSA) isolates that are resistant to all available penicillins and other ␤-lactam antimicrobial drugs (7).…”