Therapeutic interventions for Clostridioides difficile infection (CDI) could make use of a glucosyltransferase domain (GTD) as an ideal molecular target, potentially yielding new, effective treatments for this deadly disease.
The study, published in Science Advances, provided new insights into TcdB, the toxic molecular weaponry of C. difficile and its hypervirulent strains, creating an opportunity to disarm it.
CDI is the leading cause of antibiotic-associated diarrhoea and gastroenteritis-associated deaths worldwide, accounting for 500 000 cases and 29 000 deaths in the US every year and is classified by the Centers for Disease Control and Prevention as one of the top health threats. The emergence and spread of hypervirulent C. difficile strains is of global concern, resembling as it does the occurrence of new virus variants in current COVID pandemic. TcdB is one of two homologous C. difficile exotoxins, and TcdB alone is capable of causing the full spectrum of CDI diseases.
“We focused on the structure and function of TcdB’s crucial GTD, which is the toxin’s ‘warhead.’ The GTD is delivered by the toxin inside the host cells and causes most of the cytosolic damage to patients,” said corresponding author Rongsheng Jin, PhD, professor in the Department of Physiology & Biophysics at the UCI School of Medicine. “We discovered molecular mechanisms by which the GTD specifically recognises and blocks the physiological functions of the human GTPases Rho and R-Ras enzyme families that are crucial signaling molecules.”
The team also showed that the classic form of TcdB and the hypervirulent TcdB recognise their human targets in different ways, leading to distinct structural changes to the host cells caused by bacterial invasion.
“Once the GTD of TcdB is inside the cells, it is shielded by our cells and becomes inaccessible to passive immunotherapy. But our studies suggest that small molecule inhibitors could be developed to disarm the GTD, which will directly eliminate the root cause of disease symptoms and cellular damage,” Prof Jin explained. “This new strategy can potentially be integrated with and complement other CDI treatment regiments.”
Source: UCI School of Medicine
