CSB Core Faculty
Structural and Chemical Biology of Membrane Proteins and Related Diseases
While about 1/3 of all proteins are membrane proteins, less than 0.2% of solved high resolution protein structures represent membrane proteins because of difficulties in applying classical methods of structural determinations to proteins of this class. Thus, it can be argued that membrane proteins are the greatest remaining frontier of structural biology. This area is particularly important because of the critical medical relevance of membrane proteins. Over 60% of all drug molecules target membrane proteins. Moreover, hundreds of diseases involve the misassembly or misfolding of integral membrane proteins. The Sanders lab is devoted to characterizing the structures, folding and misfolding, and molecular mechanisms of membrane proteins using a variety of biochemical and biophysical methods (but especially NMR). We are a biological problem-oriented lab. However, some of the problems we wish to solve require in-house development of new methods and technologies.
Membrane Proteins involved in Misfolding-Based Diseases: Peripheral Myelin Protein 22
Many diseases are linked to protein misfolding induced by mutations or other factors. Peripheral myelin protein 22 (PMP22) has four transmembrane segments and is a critical component of the myelin sheath surrounding the axons of the peripheral nervous system. Mutations in PMP22 lead to Charcot-Marie-Tooth Disease, a common form of muscular dystrophy. These mutations appear to result in misfolding of the protein. Studies of the structures, folding, stability, and molecular interactions of both wild type and disease-associated mutants of human PMP22 are being conducted in order to illuminate how mutations in this protein results in altered molecular properties which may be directly connected with disease. These studies rely upon preparative molecular biology/protein chemistry and NMR spectroscopy.
CCR5 Chemokine Receptor: a G protein-coupled receptor which serves a co-factor for HIV-1 infection.
The G protein-coupled receptor (GPCR) family is the target of a significant fraction of all drugs (greater than 1/3). However, there is only a single high resolution structure available for any of the roughly 700 human members of this family-that of the dark state of rhodopsin. The chemokine receptors are GPCRs which play important roles in leukocyte trafficking and activation as part of host defense. It is becoming clear that these receptors also play critical roles in hematopoiesis, angiogenesis, and neuronal development. It is also now known that the CCR5 chemokine receptor serves as the requisite co-receptor for the AIDS HIV-1 viral infection of immune cells. CCR5 is considered to be an important target for candidate AIDS prophylactic and therapeutic agents. We are conducting structural studies of human CCR5 using NMR and other techniques.
G Protein-Coupled Receptors that misfold, causing disease.
number of GPCRs are also subject to mutations which result in protein misfolding
and disease. For example mutations in rhodopsin result in retinitis pigmentosa,
a common cause of blindness, and other
Diacylglycerol Kinase: an antimicrobial target and a model system for studies of membrane protein folding, and catalysis.
DAGK has three transmembrane segments per monomer and functions as a 40 kDa homotrimer. The prokaryotic form of this enzyme is structurally and functionally unrelated to eukaryotic DAGK and plays critical roles in microbial physiology. We want to know everything there is to know about this protein including its structure, catalytic mechanism, how it folds and misfolds, and how it can be inhibited in pathogenic bacteria. We have been carrying studies of DAGK using a library of single-Cysteine DAGK mutants provided by the lab of James Bowie (UCLA). Techniques employed by our lab include NMR spectroscopy, disulfide mapping, steady state enzyme kinetics, inhibitor design and synthesis, and molecular biology.