Three-dimensional structures of proteins by x-ray crystallographic analysis
The biochemical importance of carbohydrates cannot be overstated for they are essential elements in nearly every physiological process and represent the most abundant biomolecules in living systems. Apart from their role in providing metabolic energy, carbohydrates are involved in a wide range of biological processes including the immune response, cell-cell interactions, fertilization, cell adhesion, and drug efficacy, among others. The focus of our research is on the unusual di- and trideoxyhexoses, which are found attached to important antibiotics such erythromycin A, antitumor agents such adriamycin, or insecticides such as spinosad. The laboratory is also interested in the unusual sugars found in the O-antigens of Gram-negative bacteria. O-antigens differ among bacteria with respect to sugar content and linkages, are highly immunogenic, and serve as important virulence factors
Specifically, our work is aimed at understanding the structures and functions of the enzymes involved in the biosynthesis of unusual di- and trideoxyhexoses. General techniques utilized in the laboratory include x-ray crystallography, site-directed mutagenesis, enzymatic synthesis of appropriate nucleotide-linked sugar ligands, and kinetic analyses. Our investigations have revealed unprecedented chemistries and have provided important and fundamental contributions to mechanistic enzymology.
At present the laboratory is funded by grants from the NIH (DK47814) and the NSF (0849274). Work funded by the NIH focuses on the enzymes involved in the biosynthesis of such unusual sugars as desosamine, tyvelose, colitose, and perosamine. By understanding the structures and functions of these proteins it is possible to design modified enzymes with altered substrate specificities thereby yielding new “designer” sugars not normally encountered in Nature. Indeed, we have recently produced a novel trideoxysugar, 3,4,6-trideoxy-D-mannose.
Work funded by the NSF grant centers around the enzymes involved in the production of the unusual sugars D-forosamine and D-rubranitrose. These sugars contain novel functional groups, and the proposed pathways for their production contain some very unusual enzymes that are not well characterized.
The NSF grant also provides an exciting opportunity for middle school students to be involved in cutting-edge biochemical research. Funding from the grant has allowed for the development of Project CRYSTAL (Crystallographers Researching with Young Scientists: Teaching And Learning). Project CRYSTAL’s mission is twofold: first, to instill a love for chemistry in middle school students by studying the inner workings of nutrition, thereby leading to healthy life choices; and second, to provide hands-on laboratory experience in an active, state-of-the-art research laboratory thus fostering interest in a future career in the field of science. Details concerning the program can be found on the Project CRYSTAL link. The benefits resulting from the educational component of the NSF grant are enormous. First, students from grades sixth to eighth have the opportunity to work in an active research laboratory on biologically relevant projects, which will ultimately lead to publications. Secondly, the graduate students participating in the program have the opportunity to teach in a laboratory setting and thus are on a more positive trajectory towards establishing meaningful and fulfilling careers.