β-sitosterol interacts with pneumolysin to prevent Streptococcus pneumoniae infection.

Abstract

Pneumolysin is one of the major virulence factors elaborated by Streptococcus pneumoniae; this toxin is a member of the cholesterol-dependent cytolysins. Engagement of cholesterol induces the formation of a multi-subunit complex by pneumolysin that lyses host cells by forming pores on the membrane. Because pneumolysin released by bacteria which have been killed by conventional antibiotics is still active, agents capable of directly attacking the toxin are considered advantageous against antimicrobials in the treatment of S. pneumoniae infections. Here we found that the phytosterol, β-sitosterol, effectively protects against cell lysis caused by pneumolysin. This compound interacts with the toxin at Thr459 and Leu460, two sites important for being recognized by its natural ligand, cholesterol. Similar to cholesterol, β-sitosterol induces pneumolysin oligomerization. This compound also protects cells from damage by other cholesterol-dependent toxins. Finally, this compound protects mice against S. pneumoniae infection. Thus, β-sitosterol is a candidate for the development of anti-virulence agents against pathogens that rely on cholesterol-dependent toxins for successful infections.

• Authors: Hongen Li, Xiaoran Zhao, Jianfeng Wang, Yu Dong, Song Meng, Rui Li, Xiaodi Niu, Xuming Deng
• Journal: Scientific reports (Sci Rep) Vol. 5 Pg. 17668 (Dec 03 2015) ISSN: 2045-2322 [Electronic] England
• PMID: 26631364 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Bacterial Agents
• Bacterial Proteins
• Sitosterols
• Streptolysins
• plY protein, Streptococcus pneumoniae
• gamma-sitosterol
• Cholesterol

Topics

• Animals
• Anti-Bacterial Agents (chemistry, metabolism, pharmacology)
• Bacterial Proteins (chemistry, genetics, metabolism)
• Binding Sites
• Cholesterol (chemistry, metabolism)
• Hemolysis (drug effects)
• Humans
• Lung (cytology, drug effects)
• Male
• Mice, Inbred C57BL
• Models, Molecular
• Pneumococcal Infections (drug therapy, microbiology)
• Sitosterols (chemistry, metabolism, pharmacology)
• Streptococcus pneumoniae (genetics, pathogenicity)
• Streptolysins (chemistry, genetics, metabolism)
• Surface Plasmon Resonance