Analysis of a fragment of the endotoxin binding site of Factor C (360G-Wellcome-202421_Z_16_Z)

Horseshoe Crab blood has a unique ability to detect bacterial agents. This phenomenon has long been exploited by the pharmaceutical industry to create assays that ensure sterility of drugs or medical equipment. Although much is known about the signalling cascade eliciting the response following the exposure to LPS endotoxin, the specific molecular events underlying this process are still unknown. Factor C has been identified as the protein triggering the cascade of events leading to bacterial inactivation. The protein exists as a zymogen. The binding of endotoxin results in a conformational change that activates its serine protease causing autolysis. This triggers the cascade that causes blood coagulation and bacterial neutralisation. The high affinity of Factor C for the endotoxin is important when considering developing a highly sensitive detection system. As part of the Smith lab’s work to fully characterise the molecular mechanism of the conformational switch in Factor C, the aim of the project is to map the endotoxin binding site on the LPS-binding CCP1 domain from L. polyphemus Factor C, providing an answer to the question: How does lpFC recognise endotoxin?