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Function and Bioligical Relevance

Bap1 is one of the major extracellular matrix proteins along with RbmA and RbmC. These proteins are found in the bacterium Vibrio Cholerae and functions in biofilm architecture and surface attachment. V. Cholerae is involved in the progression of cholera. Bap1 is composed of two domains, a β-propeller domain, and a β-prism domain. The main role of the protein is to bind citrate and carbohydrates, which occurs in the binding pocket of the β-prism domain.

Implications

The function of Bap1 should be researched more to help us understand how cholera infects/spreads in contaminated water and food. Infected food/water with "V. Cholerae" can cause cholera if contaminated water or food is consumed. Treatment for cholera is getting more challenging with the increasing use of the antibiotics and the bacterium becoming more resistant to the treatment. This is a big issue considering there are millions of people that don't have access to clean drinking water with an estimated 2.9 million cases and almost 100,000 deaths per year ^[1]. With more research on how Bap1 functions in V. Cholerae, the spreading of cholera will be understood better and should be able to be controlled better.

Structural highlights

Bap1 is a two-domain assembly which is made up of an interrupted by a β-prism domain. The β-propeller domain is the larger of the two domains while the β-prism is the smaller of the two. The β-propeller is composed of 8 β-sheets with 3 greek keys present in between β-sheets 5 and 6 of the propeller ^[2]. It is believed the lectin binding site is in the β-prism domain.

There has not been a catalytic triad found for Bap1, but several amino acids are believed to play a role in the binding of citrate and carbohydrates. There are 6 amino acids believed to bind carbohydrates: Gly-344, Ala-345, Val-346 Asp-348, His-500, and Lys-501 ^[2]. With the exception of His-500, the other amino acids are structurally the same as the binding site of carbohydrates in RbmC. The amino acids interact with the substrate by either hydrogen bonding or Van der Waals forces. The binding site for citrate and carbohydrates is at the end of the β-prism which has a positively charged, .

The metal-binding sites in Bap1 are believed to only have a structural purpose and little to no effect on the function of the protein ^[2]

Energy Transformation

Since the function of Bap1 is to attach biofilms together, there is no energy transformation for this protein.