Our lab has worked predominantly on aspects of basic discovery research in the fields of exopolysaccharides, and Type IV pilus assembly.
Exopolysaccharide polymerization, modification and export
Exopolysaccharides are a major component of many microbial biofilms. These long sugar polymers are often found both associated with the bacterial or fungal cell surface and as a secreted form. Exopolysaccharide biosynthesis is a multistep process that requires the polymerization of nucleotide-sugar precursors, and transport across either the cytoplasmic or plasma membrane. In the case of Gram-negative bacteria the polymer also needs to traverse the periplasm and be exported from the cell. The properties of the polymer are frequently modulated by chemical modification, which can occur either in the periplasm or extracellular space.
Ongoing projects seek to determine the molecular mechanism(s) involved in the biosynthesis of:
Type IV pilus assembly
Type IV pili (T4P) are strong flexible filaments that mediate attachment to both living and artificial surfaces. They are also involved in bacteriophage adsorption, DNA uptake, biofilm initiation and development, and “twitching motility”, a unique form of surface-associated movement whereby the bacteria pull themselves rapidly towards or along a surface by retracting their T4P. Bacteria lacking T4P cannot adhere to surfaces and are therefore avirulent.
Regulation and assembly of the T4P is a complex process involving over 50 proteins. We are interested in understanding how a subset of the proteins in this molecular machine interact with each other to assembly, extend and retract the pilus.