Session 6, Abstract 35

INVESTIGATION OF THE FOLD SWITCHING MECHANISM OF THE BIOLOGICAL CLOCK PROTEIN ​KAIB

Michael I. Montoya* and Joel Heisler (Andy LiWang), Chemistry and Chemical Biology, School of Natural Sciences, University of California, Merced, 5200 N Lake Rd., Merced, CA 95343.

The predictable changes in temperature and light brought about by the rotation of the Earth are anticipated by the biological clock in nearly all organisms. The most simplistic model used for studying biological rhythm is composed of the KaiA, KaiB, and KaiC three-protein system within cyanobacteria. Although KaiB exists mainly as a tetramer, recent literature has shown that elimination of nine N-terminal residues shifted equilibrium toward the monomeric state. KaiB in its monomeric state has been found to switch between two three-dimensional folds. Utilization of PCR-mediated site-directed mutagenesis yielded a DNA sequence that encoded for a truncated KaiB9-108. Much like the behavior of the recently reported KaiB10-108, the protein obtained is expected to exhibit similar tetrameric depolymerization to the monomeric state. The success in obtaining the truncated protein would pave the way for the characterization of equilibrium and determination of the fold of each state, through biophysical techniques such as gel filtration and NMR.

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