Michael Caplow, PhD

• Publication List

RESEARCH INTERESTS:

Biochemistry of the Cytoskeleton

Our goal is to analyze factors that stabilize the dimer interface in two proteins that serve as subunits for biologically important polymerization reactions. The first of these is the tubulin a-ß heterodimer, which forms microtubules that are essential for cell transport and cell division in all eukaryotes. Understanding the stability of the intradimer bond in tubulin subunits is important because this bond is virtually identical to the interdimer bond that stabilizes microtubules and because several important antimitotic drugs act by either stabilizing or destabilizing the intersubunit bond in microtubules. The second of these is Cu,Zn superoxide dismutase 1 (SOD1), which forms protofibrils in the familial form of the neurodegenerative diseases Amyotrophic Lateral Sclerosis (FALS). Understanding the stability of the SOD1 intradimer bond is important because we and others have found that dimer dissociation is the first step in the in vitro formation of protofibrils that appear similar to those found in neurons in patients suffering from FALS.

Current work focuses on the role of protein cofactors in the assembly of the tubulin dimer and how the structure of the tubulin dimer interface influences dimer and microtubule stability and dynamics. Surface plasmon resonance is the key tool for these studies. In studies of SOD1 we are determining how different alleles of the protein that result in FALS influence the kinetics of each of the three steps in SOD1 aggregation; i.e., dimer dissociation, loss of metals and protofilament formation.

 
REPRESENTATIVE PUBLICATIONS:

Khare SD, Caplow M, Dokholyan NV. FALS mutations in Cu, Zn superoxide dismutase destabilize the dimer and increase dimer dissociation propensity: a large-scale thermodynamic analysis. Amyloid. 2006 Dec;13(4):226-35.

Khare SD, Caplow M, Dokholyan NV. The rate and equilibrium constants for a multistep reaction sequence for the aggregation of superoxide dismutase in amyotrophic lateral sclerosis. Proc Natl Acad Sci U S A. 2004 Oct 19;101(42):15094-9.

Caplow M, Fee L. Concerning the chemical nature of tubulin subunits that cap and stabilize microtubules. Biochemistry. 2003 Feb 25;42(7):2122-6.

Hunter AW, Caplow M, Coy DL, Hancock WO, Diez S, Wordeman L, Howard J. The kinesin-related protein MCAK is a microtubule depolymerase that forms an ATP-hydrolyzing complex at microtubule ends. Mol Cell. 2003 Feb;11(2):445-57.

Caplow M, Fee L. Dissociation of the tubulin dimer is extremely slow, thermodynamically very unfavorable, and reversible in the absence of an energy source. Mol Biol Cell. 2002 Jun;13(6):2120-31.