@misc{10481/109742,
year = {2009},
month = {8},
url = {https://hdl.handle.net/10481/109742},
abstract = {Gelsolin consists of six homologous domains (G1-G6), each containing a conserved Ca-binding site. Occupation of a subset of these sites enables gelsolin to sever and cap actin filaments in a Ca-dependent manner. Here, we present the structures of Ca-free human gelsolin and of Ca-bound human G1-G3 in a complex with actin. These structures closely resemble those determined previously for equine gelsolin. However, the G2 Ca-binding site is occupied in the human G1-G3/actin structure, whereas it is vacant in the equine version. In-depth comparison of the Ca-free and Ca-activated, actin-bound human gelsolin structures suggests G2 and G6 to be cooperative in binding Ca(2+) and responsible for opening the G2-G6 latch to expose the F-actin-binding site on G2. Mutational analysis of the G2 and G6 Ca-binding sites demonstrates their interdependence in maintaining the compact structure in the absence of calcium. Examination of Ca binding by G2 in human G1-G3/actin reveals that the Ca(2+) locks the G2-G3 interface. Thermal denaturation studies of G2-G3 indicate that Ca binding stabilizes this fragment, driving it into the active conformation. The G2 Ca-binding site is mutated in gelsolin from familial amyloidosis (Finnish-type) patients. This disease initially proceeds through protease cleavage of G2, ultimately to produce a fragment that forms amyloid fibrils. The data presented here support a mechanism whereby the loss of Ca binding by G2 prolongs the lifetime of partially activated, intermediate conformations in which the protease cleavage site is exposed.},
organization = {Heart and Stroke Foundation of BC & Yukon},
organization = {Canada Foundation for Innovation},
organization = {Michael Smith Foundation for Health Research},
organization = {Howard Hughes Medical Institute},
organization = {Canadian Institutes of Health Research},
organization = {National Research Program for Genomic Medicine},
publisher = {PNAS},
keywords = {Actin},
keywords = {Calcium activated},
keywords = {Calcium dependent},
keywords = {TIRF},
title = {Ca2+ binding by domain 2 plays a critical role in the activation and stabilization of gelsolin},
doi = {10.1073/pnas.0812374106},
author = {Nag, Shalini and Ma, Qing and Wang, Hui and Chumnarnsilpa, Sakesit and Lee, Wei Lin and Larsson, Marten and Kannan, Balakrishnan and Hernández-Valladares, María and Burtnick, Leslie D. and Robinson, Robert C.},
}