Paper Citing NAMD - Abstract
Lou, Jizhong; Yago, Tadayuki; Klopocki, Arkadiusz G.; Mehta, Padmaja; Chen, Wei; Zarnitsyna, Veronika I.; Bovin, Nicolai V.; Zhu, Cheng; McEver, Rodger P.
Flow-enhanced adhesion regulated by a selectin interdomain hinge
JOURNAL OF CELL BIOLOGY, 174:1107-1117, SEP 25 2006
L-selectin requires a threshold shear to enable leukocytes to tether to and roll on vascular surfaces. Transport mechanisms govern flow-enhanced tethering, whereas force governs flow-enhanced rolling by prolonging the lifetimes of L-selectin-ligand complexes (catch bonds). Using selectin crystal structures, molecular dynamics simulations, site-directed mutagenesis, single-molecule force and kinetics experiments, Monte Carlo modeling, and flow chamber adhesion studies, we show that eliminating a hydrogen bond to increase the flexibility of an interdomain hinge in L-selectin reduced the shear threshold for adhesion via two mechanisms. One affects the on-rate by increasing tethering through greater rotational diffusion. The other affects the off-rate by strengthening rolling through augmented catch bonds with longer lifetimes at smaller forces. By forcing open the hinge angle, ligand may slide across its interface with L-selectin to promote rebinding, thereby providing a mechanism for catch bonds. Thus, allosteric changes remote from the ligand-binding interface regulate both bond formation and dissociation.
