We are interested in the understanding, prediction and structural analysis of calcium binding proteins in biological and chemical systems as well as developing new methods and probes for bioinformatics, chemical biology, and diagnosis and treatment of diseases by protein engineering and design.
The first major interest focuses on the mechanisms of molecular recognition, especially the role of calcium in biological and chemical systems. Ca(II) is an essential component in the biomineralization of teeth, bones, and shells. It regulates cellular processes, such as cell division and growth, secretion, ion transport, and muscle contraction, in different compartments through interactions with Ca(II) -binding proteins and temporal and spatial changes in concentration. Many human diseases, including various cardiomyopathies, Alzheimer's disease, and lens cataract formation are known to be associated with altered Ca(II)-binding affinities and altered Ca(II) signaling.
There are two major barriers to understanding the molecular mechanisms of Ca(II) -dependent biological function. First is the lack of established rules relating Ca(II)-binding affinity with specific structural aspects of proteins. This complication is exacerbated by the complexities encountered in cooperative, multi-site systems, and the use of Ca(II)-binding energy to effect conformational changes in proteins. To date, understanding the role of Ca(II) in regulating extracellular Ca(II) signaling is mainly hindered by a lack of knowledge regarding Ca(II) binding sites. A second barrier in understanding the role of Ca(II) in signaling is the lack of sensors to monitor Ca(II) concentration changes in different sub-cellular environments. To overcome these barriers and limitations associated with naturally occurring Ca(II)-binding proteins, we have developed two novel protein engineering approaches (designing and grafting) for creating a single Ca(II)-binding site, allowing the dissection of the key structural factors that control Ca(II)-binding affinity, conformational change and cooperativity. We have also developed protein-based sensors that can be specifically targeted to the cellular compartments to monitor Ca(II) concentration change.
The second research interest focuses on developing new methods and probes for chemical biology and the diagnosis and treatment of diseases. Currently there is an urgent need to predict calcium binding proteins and their biological functions (calciomics) and to develop research and diagnostic tools for linking our knowledge derived from in vitro studies to living cells and organisms. By applying our expertise in protein engineering and design and structural biology, we wish to develop new tools for monitoring biological processes and diagnosis human diseases in live cells and animals (e.g. fluorescence and magnetic resonance imaging probes). Our research focuses are summarized in Fig. 1 and salient features of each research interest in two major areas are summarized below.