Overview

The emergence of new pathogens, the resurgence of old pathogens, and increasing antibiotic resistance to them reinforce the need for elucidating mechanisms of microbial pathogenesis using all possible methodologies. Structural investigation of microbial pathogenesis, the focal point of my research, involves the use of macromolecular crystallography applied to studies of Gram-positive bacterial organisms, with two focal interests. The first is host-pathogen interactions, using Streptococcus species as a model system. The second focus is on essential processes leading to the formation and germination of spores in selected groups of Gram-positive bacteria, using Bacillus species as a model system. With these two broad research fronts we hope to better and more completely characterize Gram-positive bacteria.

Other structural methods employed in the study of microbial pathogenesis are analytical sedimentation, mass spectrometry, spectral analyses (atomic absorption, circular dichroism, fluorescence, laser scattering, nuclear magnetic resonance), and a variety of biochemical and molecular biology approaches to investigate the general processes mentioned above. Molecular modeling and structure-based design applied to essential enzymes and processes involved in microbial pathogenesis provide additional information.

In addition, we take information gained from the many completed and several nearly completed bacterial and eukaryotic genomic sequences, analyze it computationally using various genomic algorithms, and apply it to investigate macromolecules of organisms having known genomic sequences, taking into account a broader evolutionary scope. The developing tools of structural genomics, such as molecular modeling of new structures related to those already solved in our lab, are being applied to study structure, function and evolution of these entities. We then apply this information to broaden our research by comparing structural targets from the Streptococcus and Bacillus genera with comparable targets in other organisms. Such analysis allows us to comment on evolutionary properties of the processes under investigation in the laboratory.

From a methodological point of view of crystallography, structure determination in our laboratory is primarily based on utilizing multiwavelength anomalous dispersion (MAD) techniques based not only on the presence of selenium atoms in the structure but also on halide ions, for example. Whenever possible, our lab takes advantage of automated procedures of macromolecular structure solution, fitting, and refinement. These techniques become increasingly important especially for solving multiple, streamlined structures anticipated from microbial genomes.
Our laboratory has expertise in using novel structure determination and analysis algorithms, and other methods that are currently being developed and optimized.