Pathogenic Role of β‐Endo‐N‐Acetylglucosaminidase ( <scp>LytB</scp> ) in <scp> <i>Streptococcus pneumoniae</i> </scp> : Functional Insights Into a Choline‐Binding Cell Wall Hydrolase

Streptococcus pneumoniae, which imposes the highest burden on children under 2 years of age, immunocompromised individuals and the elderly in developing countries, causes a range of diseases including pneumonia, meningitis, bacteraemia and septicaemia. Its virulence is driven by an array of surface proteins categorised into four families: non-classical surface proteins, LPXTG-sequence proteins, lipoproteins and choline-binding proteins. The different choline-binding proteins include LytA, LytB, LytC, PspA, CbpA, CbpD, CbpL and CbpF, each with varying numbers of choline-binding repeats in their domains. This review focuses on β-endo-acetylglucosaminidase (LytB), a non-autolytic peptidoglycan hydrolase, emphasising its pivotal role in the pathogenic mechanisms of S. pneumoniae. LytB, with its multiple functional domains (CB, SH3B, WW and GH73), facilitates adhesion to host tissues, promoting initial colonisation, immune evasion and subsequent bacterial dissemination. These functions enable the bacterium to establish invasive diseases. LytB's interactions with host cells and extracellular matrix components underscore its importance in S. pneumoniae pathogenicity. In summary, LytB is a multifaceted choline-binding protein critical to pneumococcal virulence. A detailed understanding of its mechanisms and domain-specific interactions offers promising avenues for the development of novel chemical and plant-based therapeutic strategies, including drugs and vaccines, to combat pneumococcal infections.