Research
My
major research interest is the structure and function
of proteins involved in bacterial pathogenesis. Current
work is focused on the preparation of crystals of bacterial
virulence factors suitable for x-ray diffraction. A
number of investigations are underway.
Gly1Orf1
is a secreted protein that affects the toxicity of Neisseria
gonorrhoeae to human fallopian tubes in organ culture.
This protein is produced only in pathogenic Neisseria
species. In collaboration with Dr. Cindy Arvidson (MSU),
hexagonal (space group P63) data quality crystals of
the 15 kDa protein have been prepared. A synthetic mother
liquor compatible with cryocrystallography has been
developed. I have collected a native data set to 2.1Å
resolution, and a heavy atom derivative data set. More
recently, MAD data sets of a selenomethionine derivative
were collected.
Crystallization
studies are in progress, in collaboration with Dr. Kwong-Kwok
Wong (Pacific Northwest National Laboratories), of a
Salmonella typhimurium cytotoxin. This >300 kDa protein
is an RTX-like toxin that forms pores in the cell membrane.
We are currently working with an 88 kDa domain of the
protein with 6 RTX-toxin motifs (a nanopeptide sequence)
that has been purified and shown to be cytotoxic.
Drs.
Fred Heffron and Sunghee Chai (Oregon Health Sciences
University) have provided plasmid constructs for virulence
factors from Salmonella typhimurium. A protein currently
named IMS75 was discovered in a screen for genetic loci
that, when disrupted, impair macrophage survival. This
protein was also found in a subsequent screen for proteins
that are localized to the host cytoplasm. IMS75 thus
appears to be transported from the phagolysosome to
the host cytoplasm where it may interact to allow survival
of the bacteria within the phagolysosome.
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