Structure and Function of Lipases

Description of projects available to graduate students:
Fats are vital dietary components that provide energy and essential metabolites. Fat digestion requires integration of gastric and pancreatic lipases, which have specific, individual functions, and the absorptive properties of the intestine. Pancreatic lipases are essential for the efficient utilization of dietary triglycerides, minor lipids and vitamin esters. Although much is known about the biochemical properties of pancreatic lipases, the physiological role of these lipases remains less clear. Medically, lipases figure prominently in nutritional therapy, in therapy for obesity and in the pharmaceutical industry. Complete understanding of dietary fat digestion requires thorough knowledge of the molecular details underlying lipolysis by pancreatic lipases. These details will also enhance our ability to specifically design lipases with highly selective substrate specificity and increased activity for therapeutic and pharmaceutical applications. My lab focuses on the predominant digestive lipase, pancreatic triglyceride lipase (PTL) and two homologues, pancreatic lipase related proteins 2 and 3 (PLRP2 and PLRP3). PTL and PLRP2 are physiologically important; it is their function that must be replaced by recombinant lipases in nutritional therapy. PTL is a target for obesity therapy. Despite nearly identical primary and tertiary structures, PTL and PLRP2 have markedly different substrate specificities and requirements for colipase, an essential cofactor for PTL. Comparison of these two homologues provides a unique opportunity to define the structural elements that dictate substrate specificity. PLRP3 is a new member of the pancreatic lipase gene family and will provide additional insight into the structures that govern substrate specificity. Importantly, these lipases share tertiary structure and common catalytic machinery with lipases from divergent and multiple sources. Thus, information about structure-function relationships in pancreatic lipases will apply to other lipase family members. The knowledge gained upon completion of our studies will enhance understanding of dietary fat digestion and result in safer inhibition of dietary fat digestion as therapy for obesity and hepatosteatosis. It will bring us closer to the rational design of lipases with selective substrate specificity and increased activity for nutritional therapy and drug synthesis.
We have the following projects 1)To develop and specific inhibitors of PTL in vitro and in vivo; 2)To characterize the substrate specificity and colipase dependence of PLRP3; 3)To define the molecular basis for differences in substrate specificity between PTL and PLRP2.

Techniques graduate student will learn:
Standard DNA techniques, Site-directed mutagenesis, Protein expression in yeast, Western blotting, Protein purification including ion-exchange, hydrophobic interaction, and gel filtration chromatography, characterization of lipases and colipase through measurements of activity and adsorption to oil-water interfaces