Warfare between Pathogens and Hosts: The Trickery of Sugars

Many hosts-pathogen interactions are often mediated by carbohydrates by the interplay between glycans and glycan binding protein (GBP).Glycans on the host cells may be bound by the pathogen GBP and glycans on the pathogens may be bound by the GBP on the host cells.Some pathogens can even take advantage of the host cell defense mechanisms to promote their survival. A. IntroductionW h e n e v e r " s u g a r s " a r e m e n t i o n e d , t h e t e r m "sweetness" is always conjured up.However, the dealings with sugars in biological systems are not always sweet.In fact, sugar-grabbing process can not only be sweet seduction, but can be bitter warfare or contemptuous trickery.For example, cholera toxin's binding of a glycolipid lead to internalization of the harmful toxin into human cells.Some acute phase proteins, such as serum mannose-binding protein (MBP) and C-reactive protein (CRP), actively capture microbes by their surface carbohydrates leading to merciless destruction.Treacherous are the carbohydrate-rich surfaces of HIV virions and Mycobacterium tuberculosis, which not only enable them to evade human surveillance, but to further promote survival and propagation.There are many other examples of such tug-of-war between pathogens and humans involving carbohydrates and carbohydrate-binding proteins (GBP) on both host cells and pathogens, which make this very interesting and intriguing topic.What, then, are the underlying principles that cause these phenomena?It is the carbohydrate-rich layers on the cell surfaces of both mammalian hosts and pathogens that are the target of GBPs of both pathogens and host.Nearly all cell surfaces, prokaryotes and eukaryotes alike, are heavily coated with carbohydrate materials (glycocalyx), such as glycoproteins and glycolipids, but others are much more complex (e.g., glycosaminoglycans).Bacterial surfaces are covered with layers of polysaccharides ---peptidoglycans, 病原体と宿主の戦い : 糖の策略 要 約