Probing myosin structural conformation in vivo by second-harmonic generation microscopy

• DOI: 10.1073/pnas.0914782107
• Publication Date: 2010-04-13T03:45:08Z
• Authors: V. Nucciotti; C. Stringari; L. Sacconi; F. Vanzi; L. Fusi; M. Linari; G. Piazzesi; V. Lombardi; F. S. Pavone
• Keywords: Molecular motor

Understanding of complex biological processes requires knowledge molecular structures and measurement their dynamics in vivo. The collective chemomechanical action myosin molecules (the motors) the muscle sarcomere represents a paradigmatic example this respect. Here, we describe label-free imaging method sensitive to protein conformation We employed order-based contrast enhancement by second-harmonic generation (SHG) for functional cells. found that SHG polarization anisotropy (SPA) measurements report on structural state actomyosin motors, with significant sensitivity myosin. In fact, each physiological/biochemical probed (relaxed, rigor, isometric contraction) produced distinct value anisotropy. Employing full reconstruction contributing elementary emitters motor array at atomic scale, provide interpretation SPA terms conformations. applied discrimination between attached detached heads an isometrically contracting intact fiber. Our observations indicate sustains its tetanic force steady-state commitment 30% heads. Applying structure modeling unstained living tissues provides basis diagnostic tools capable probing