报告题目: Folding and Unfolding Mechanisms of Iron Sulfur Proteins Revealed by Single Molecule Force Spectroscopy
报 告 人：Prof. Hongbin Li
University of British Columbia, Canada
邀 请 人：张文科教授
Metal ions play important roles in biology. In metalloproteins, metal centers serve as active sites, as well as important structural elements to facilitate protein folding and assembly. However, it is challenging to investigate the unfolding-folding of metalloproteins due to the loss or decomposition of the metal center. Here, we combine single molecule force spectroscopy and protein engineering to investigate the unfolding-refolding mechanism of small iron sulfur proteins rubredoxin and ferredoxin. Our results revealed that the unfolding of both proteins are characterized by the initial partial unfolding of the protein followed by the rupture of the iron sulfur center and complete unraveling of the protein. However, differences in the iron chelation motif in rubredoxin and ferredoxin gave rise to distinct rupture patterns of the iron sulfur center. After complete unfolding, rubredoxin and ferredoxin were observed to refold to its holo-native form with the fully reconstituted iron sulfur center. Moreover, folding of the apo- rubredoxin was observed during the folding of rubredoxin, while apo-ferredoxin was not observed to form, revealing different roles and importance of the iron sulfur center to the holo-proteins. Our results open new avenues towards investigating the folding mechanism of metalloproteins at an unprecedented resolution.
Hongbin Li, was born in China in 1970. He obtained his bachelor degree in Polymer Engineering from Tianjin University in 1993 and PhD degree in Polymer Chemistry and Physics from Jilin University (with Profs. JIacong Shen, Xi Zhang and Hermann Gaub) in 1998. During his PhD study, he was jointly trained in University of Munich, Germany. After his postdoctoral training in Mayo Medical Center in Rochester, Minnesota, USA (with Prof. Julio Fernandez, 1999-2002), he worked as an Associate Research Scientist in Columbia University, USA. In 2004, he joined the Department of Chemistry in the University of British Columbia, Canada. Currently he is a full Professor in Chemistry. His awards include the Charles McDowell Award for Excellence in Research, Canada Research Chair in Molecular Nanoscience and Protein Engineering, NSERC Discovery Accelerator Supplement Award, Michael Smith Foundation for Health Research Career Investigator Award, Peter Wall Institute Early Career Award, JILA Distinguished Visitor Fellow and Changjiang Scholar. His research interests include protein mechanics and engineering at the single molecule level, protein-based biomaterials, as well as protein folding and unfolding dynamics.