Regulation Of MsmK On The Growth And Pathogenesis Of Streptococcus Suis

Streptococcus suisis a Gram-positive ovococci. As an opportunistic pathogen, the natural habitat of S. suisis the upper respiratory tract of pigs, particularly the tonsils and nasal cavities. Among the 33 serotypes based on capsular antigens that have been described, S. suis serotype 2（SS2） is the most frequently isolated and virulent. SS2 causes a wide variety of diseases, including septicaemia, meningitis, endocarditis and arthritis, which are not only responsible for high economic losses in the swine industry worldwide, but is also considered to be an emerging zoonotic agent causing meningitis and streptococcal toxic shock-like syndrome in humans. The primary aim of pathogenic bacteria is to gain access to nutrients rather than to cause damage to the host. Several studies have linked bacterial carbohydrate metabolism to environmental survival, colonization and virulence of SS2. Carbohydrate availability regulates virulence gene expression in SS2, and the proteins that are encoded by virulence genes are often involved in the use of alternative nutrients. In this study, we characterized functions of the ATPase Msm K which contributes to multiple carbohydrates transport, pathogenicity and cell division of SS2.1. Msm K contributes to utilization of multiple carbohydrates of SS2Acquisition and metabolism of accessible nutrients from living environment is necessary for all heterotrophic pathogens. The metabolism of α-glucans regulates the growth and virulence of SS2 at different stages of infection. Carbohydrates transport in bacteria is carried out mainly by two systems: the phosphotransferase system and the ATP binding cassette（ABC） transporter. Here, we analyzed genetic organization of msm EFG and mal XCD gene clusters in SC-19 genome. Msm EFG transporter was responsible for uptake of melibiose and raffinose, and Mal XCD transporter was responsible for uptake of degradation products of α-glucans. We identified Msm K, encoded by SSUSC84₁724, is an ATPase from SS2. Genetic and biochemistry studies revealed that Msm K energize both ABC transporters Msm EFG and Mal XCD.2. Msm K contributes to host colonization of SS2Homeostasis between bacterium and host is a prerequisite for stable colonization. At the mucosal surfaces a high ratio of α-glucans to glucose upregulates expression of metabolic pathways associated with α-glucans metabolism. Additionally, several virulence factors involved in adherence, spreading and immune escaping are upregulated, which facilitates epithelial transmigration of SS2. In the organs and tissues, glycogen released from damaged cells sustains growth of SS2. The mice challenged with low dose or high dose of Δmsm K, its survival rates exceeded that of SC-19, showed that the absence of msm K impairs SS2 infection in mice. We performed colonization assays in mice and found that the absence of Msm K actually affected streptococcal survival in mice brains and other organs during last days post-infection. The msm K deletion mutant was much more susceptible than the wild-type when exposed to mouse blood in vivo and in vitro, indicating Msm K contributes to SS2 survival in mouse bloodstream. he deletion of msm K impaired abilities of SS2 to resistant to blood killing, phagocytosis, environmental stresses and to form biofilms.Together, these data imply that Msm K acts as a multifunctional component that not only contributes to carbohydrate utilization, but also plays a role in the pathogenesis of SS2, which provides novel insights into the relationship between carbohydrate contents and pathogenesis.3. Msm K contributes to cell division of SS2Bacterial cell division is an attractive target to develop antimicrobial drugs. Research on bacterial cell division is not only driven by our curiosity to understand a fundamental biological process but also by the possibility to exploit cell division proteins as primary targets to develop novel broad-spectrum antibacterials. It is important to characterize and validate the function of cell division proteins not only in model organisms but also in pathogenic species. Potent inhibitors and therapeutic agents to effectively control S. suis infection are required to address the re-emergence of SS2 as a zoonotic pathogen in humans and the rapid increase of antibiotic-resistant strains among clinical isolates.In the present study, we have identified the protein-protein interaction network in SS2 focused on fts Z with the bacterial two-hybrid system, and the result showed that the ATPase Msm K could interact with Fts Z. Surface plasmon resonance analysis and ELISA analysis revealed its an N_domain to N_domain interaction between Msm K and Fts Z. Msm K promotes the amount of polymerized Fts Z in vitro. In the absence of Msm K, cells divide in unsuccessive parallel planes and are not perpendicular to their long axis, thus cells exhibited abnormal strains and morphology. What’s more, the transcriptional levels of several genes related to cell division changed in the mutant compared to SC-19. These results suggest that Msm K is involved in maintaining correct cell shape and in cell division. The precise role of Msm K participating in cell division still need further study.