Sandbox Reserved 1468

is found in Vibrio cholera. Its function is cleaving A subunit of cholera toxin, which plays an important role in activation of VesB and may contribute to intestinal growth or pathogenesis The substrate of VesB is any protein containing arginine (XXRXX) and the products after cleavage are (XXR+XX).

VesB has been shown to cause cholera. Cholera is a bacterial disease that is spread through contaminated food or water. Its symptoms include severe diarrhea and dehydration. Impoverished areas with lesser sanitation are most susceptible to cholera.

By studying VesB, improved treatment and prevention of cholera could be discovered. While it is not a major problem in the United States, lives could be improved and saved in areas such such as Africa, where cholera is more prevalent. This would allow more social interaction without concern of disease, which would be beneficial as many people are in close contact in these areas of contamination.

The primary of VesB is beta sheets, with some alpha helices and a few random coils. VesB has two and that make up its tertiary structure. There is an N-terminal protease domain with a trypsin/chymotrypsin fold and also a C-terminal Ig fold. shows the size of the protein and the area each molecule occupies. There are both sections of VesB. Its active site is hydrophobic, as is much of its surface. The alpha helices make up the majority of the hydrophilic areas, showing areas where water would be attracted to VesB. The crystal structure of VesB was solved without a ligand, however, any protein containing RX is a VesB ligand. His78, Asp125, and Ser221 make up the . Aspartic acid is deprotonated and proton transfer moves from histidine to aspartic acid, meaning histidine is also deprotonated. Histidine then accepts a proton from serine's hydroxyl group, allowing serine to attack a substrate. This trio of amino acids work together to help VesB effectively cleave the substrate. Asp194 and Asp 220 coordinate the N terminus amino group in active VesB. Ile16 and Ile33 occupies the hydrophobic pocket while Val159 and Val180 assist in hydrogen bonding. These amino acids help form the of VesB. assists in cleaving the substrate. coordinates an Na+ ion that binds to and allosterically enhances thrombin activity. Proline residue near inhibits this Na+ ion binding.

VesB is uncompetitively inhibited by Boc-Gln-Ala-Arg-7-amino-4-AMC. This shows that this peptide does not have an impact on VesB function and that VesB is able to effectively cleave substrate.