STRUCTURE BIOLOGY OF ORAL BACTERIAL PROTEINS THAT ERADICATE BIOFILMS

Cornell University, Ithaca NY

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Abstract

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This will be a continuation of previous projects that the PI has submitted and gotten beamtime. Briefly, we are working on enzymes that degradde and detach oral as well as meedically important biofilms. The bacterial species that produce these biofilms include Aggregatibacter actinomycetemcomitans, S. epidermidis and S. aureus. We are studying two enzymes, Dispersin B and PgaB. Both work on the ssubstrate, a homopolymer of beta(1,6)linked N-acetylglucosamine. While dispersin B cleaves the beta(1,6 linkages, PgaB deacetylates the N-acetylglucosamine groups of the polymer. Both sensitize each other in efficient removal of biofilms. We have obtained crystals of Dispersin B that diffract to 2.0 A in house. We would like to collect high resolution data for crystals that are soaked with substrate and inhibitors. The complex also diffracts to 2 A, but we are unable to resolve the ligand well in the maps. We would like to use the high resolution data to see whether this can be done. Four to 5 mutants will be brought for data collection. Some of the mutations occur at the catalytic site and others at distal sites. The hypothesis is that altough dispersin B is an exo enzyme, it does have multiple subsites. Resolution of subsite architecture will also be analyzed. The second enzyme is a deacetylase and we have good crystals that diffract to 8 A. We would like to see whether good, usuable data can be obtained.