Function analysis of choline binding domains (CBDs) of LytA, LytC and CbpD in biofilm formation of Streptococcus pneumoniae. (January 2023)

• Record Type: Journal Article
• Authors: Ji, Hongsheng; Zhou, Yingshun; Zhang, Luhua; Wang, Ying; Zhang, Feiyang; Bai, Jiawei; Li, Qin; Zhang, Zhikun
• Is Part Of: Microbial pathogenesis. Volume 174(2023)
• Publication Date: 2023-01
• Subjects: Streptococcus pneumoniae -- Choline binding domains -- Biofilm formation -- Membrane transport -- Surface charge; Pathogenic microorganisms -- Periodicals; Pathology, Molecular -- Periodicals; Communicable Diseases -- microbiology -- Periodicals; Communicable Diseases -- parasitology -- Periodicals; Micro-organismes pathogènes -- Périodiques; Pathologie moléculaire -- Périodiques; Electronic journals; 616.9041
• DOI: 10.1016/j.micpath.2022.105939
• Languages: English
• ISSNs: 0882-4010

Abstract

Abstract: Biofilm formation is an important strategy for the colonization of Streptococcus pneumoniae, which can increase the capacity to evade antibiotic and host immune stress. Extracellular choline-binding proteins (CBPs) are required for successful biofilm formation, but the function of extracellular CBPs in the process of biofilm formation is not fully understood. In this study, we tend to analyze the functions of LytA, LytC and CbpD in biofilm formation by in vitro studies with their choline-binding domains (CBDs). Biofilm formation of S. pneumoniae was enhanced when cultured in medium supplemented with CBD-C and CBD-D. Parallel assays with ChBp-Is (choline binding repeats with different C-terminal tails) and character analysis of CBDs reveal a higher isoelectric point (pI) is related to promotion of biofilm formation. Phenotype characterization of biofilms revel CBD-C and CBD-D function differently, CBD-C promoting the formation of membrane-like structures and CBD-D promoting the formation of regular reticular structures. Gene expression analysis reveals membrane transport pathways are influenced with the binding of CBDs, among which the phosphate uptake and PTS of galactose pathways are both up-regulated under conditions with CBDs. Further, extracellular substances detection revealed that extracellular proteins increased with CBD-A and CBD-D, exhibiting as increase in extracellular high molecular weight proteins. Extracellular DNA increased under CBD-A but decreased under CBD-C and CBD-D; Extracellular phosphate increased under CBD-C. These support the alterations in membrane transport pathways, and reveal diverse reactions to extracellular protein, DNA and phosphate of these three CBDs. Overall, our results indicated extracellular CBP participate in biofilm formation by affecting surface charge and membrane transport pathways of pneumococcal cells, as well as promoting reactions to extracellular substances. Highlights: Choline-binding domains (CBDs) of LytC and CbpD promote biofilm formation of S. pneumoniae. Promotion effect on biofilm formation relate to the isoelectric point of CBDs. The binding of CBDs influence the membrane transport pathways. The binding of CBDs promote reactions to extracellular substances.