Leslie Laconte

Office:	BSBE 1-138
Phone:	(612) 625-2466
Fax:	(612) 624-0632
Mail:	312 Church St. Minneapolis, MN 55455
Email:	ll@ddt.biochem.umn.edu

Research Interests:

My current biochemical research interests center around the spin-labeled myosin light chain project initiated by Ingrid Brust-Mascher and Josh Baker. Briefly, a specific site on the regulatory light chain of chicken gizzard myosin is labeled with a nitroxide spin label (observable with EPR spectroscopy) and then exchanged for the native light chain of scallop muscle fibers. These fibers are then observed with EPR spectroscopy during various physiological states (rigor, relaxation, and contraction) and changes in the orientation of the probe are monitored.

Most recently, I have been using this spin-labeled scallop fiber system to observe transient changes in the RLC structural distributions using caged ATP to initiate relaxation and contraction. From these studies it will be possible to further describe the kinetics of structural changes within a muscle fiber.

In addition to this experimental work, I have collaborated with Greg Wilde, Will Meland, and Michael Enz to computationally model the dynamics of the spin labels FDNASL and IASL when attached to the RLC or myosin itself. From molecular dynamics trajectories, we are able to predict the order parameter of the spin label as well as its orientation with respect to the muscle fiber. This allows us to perform "virtual mutagenesis" on the RLC!

Techniques: EPR spectroscopy of proteins labeled with nitroxide spin labels and simultaneous measurement of muscle fiber force with tensiometer. Biochemical assays to determine ATPase rates and protein content. Gel electrophoresis (native and SDS-PAGE). Computer modeling of spin-labeled proteins using the software package from Molecular Simulations, Inc., InsightII.

Publications:

Baker JE, Brust-Mascher I, Ramachandran S, LaConte LEW, and Thomas DD (1998) A large and distinct rotation of the myosin light chain domain upon muscle contraction. PNAS, 95:2944-2949.

Brust-Mascher I, LaConte LEW, Baker JE, and Thomas DD (1999) Myosin light-chain domain rotates upon muscle activation but not ATP hydrolysis. Biochemistry, in press.

Baker JE, LaConte LEW, Brust-Mascher I, and Thomas DD (1999) Mechanochemical coupling in spin-labeled, active, isometric muscle. Biophys. J., in press.

LaConte LEW, Baker JE, Brust-Mascher I, Thomas DD (1999) Biochemical and mechanical modulation of two distinct orientations of the spin-labeled myosin light chain domain in muscle. Biophys. J., 76:A162.

Smith W, LaConte LEW, Wilde G, Meland W, Enz M, Lu R, and Thomas DD. (1999) Site-directed spin labeling of the myosin regulatory light chain: Coordination of EPR spectroscopy and computer modeling. Biophys. J., 76:A162.

LaConte LEW, Brust-Mascher I, Baker JE, and Thomas DD (1998) Large rotation of the regulatory domain of myosin upon muscle contraction detected by spin label EPR. Biophys J, 74:A363.

Brust-Mascher I, Baker JE, LaConte LEW, Ramachandran S, Lu R, Thomas DD (1997) Orientations of the regulatory domain of myosin studied by site-directed spin labelling of regulatory light chains in scallop muscle fibers. Biophys J, 72:A276.

webmaster@ddt.biochem.umn.edu