Event
Bioengineering Seminar Series: Philip Bryan
Friday, November 13, 2009
11:00 a.m.
Room 2108, Chemical and Nuclear Engineering Bldg.
Professor Adam Hsieh
hsieh@umd.edu
Engineering Proteins with Switchable Functions
Presented by Philip Bryan
Professor, Structural Biology
Center for Advanced Research in Biotechnology (CARB)
University of Maryland Biotechnology Institute
Recent insights into protein structure and function relationships have created an ability to engineer proteins with switchable functions. This creates a vast potential for building protein-based nanodevices.
In the first example, we provide a structural and mechanistic description of how a protein changes its fold and function, mutation by mutation. We show that an IgG-binding, 4β+α fold can be transformed into an albumin-binding, 3-α fold via a mutational pathway in which neither function nor native structure is completely lost. We evaluate the stability of all mutants along the pathway, determine key high-resolution structures by NMR and provide an explanation of the switching mechanism. We show that the conformational switch from 4β+α to 3-α structure can occur via a single amino acid substitution. We further show that a bifunctional protein exists at the switch point with affinity for both IgG and albumin.
In the second example, we describe methods to engineer highly-specific proteases which are tightly regulated by small molecules. The centerpiece of this work is a genetic selection system in which the protease, the substrate sequence, and the regulatory co-factor are co-evolved. We are creating proteases with powerful applications as biological detectors, for protein purification, for proteomic analysis, and for therapeutics.
