@article {348,
	title = {The calcium activation of gelsolin: Insights from the 3 angstrom structure of the G4-G6/actin complex},
	journal = {Journal of Molecular Biology},
	volume = {324},
	number = {4},
	year = {2002},
	note = {ISI Document Delivery No.: 625PRTimes Cited: 48Cited Reference Count: 32},
	month = {Dec},
	pages = {691-702},
	type = {Article},
	abstract = {Gelsolin participates in the reorganization of the actin cytoskeleton that is required during such phenomena as cell movement, cytokinesis, and apoptosis. It consists of six structurally similar domains, G1-G6, which are arranged at resting intracellular levels of calcium ion so as to obscure the three actin-binding surfaces. Elevation of Ca2+ concentrations releases latches within the constrained structure and produces large shifts in the relative positioning of the domains, permitting gelsolin to bind to and sever actin filaments. How Ca2+ is able to activate gelsolin has been a major question concerning the function of this protein. We present the improved structure of the C-terminal half of gelsolin bound to monomeric actin at 3.0 Angstrom resolution. Two classes of Ca2+-binding site are evident on gelsolin: type 1 sites share coordination of Ca2+ with actin, while type 2 sites are wholly contained within gelsolin. This structure of the complex reveals the locations of two novel metal ion-binding sites in domains G5 and G6, respectively. We identify both as type 2 sites. The absolute conservation of the type 2 calcium-ligating residues across the six,domains of gelsolin suggests that this site exists in each of the domains. In total, gelsolin has the potential to bind eight calcium ions, two type 1 and six type 2. The function of the type 2 sites is to facilitate structural rearrangements within gelsolin as part of the activation and actin-binding and severing processes. We propose the novel type 2 site in G6 to be the critical site that initiates overall activation of gelsolin by releasing the tail latch that locks calcium-free gelsolin in a conformation unable to bind actin. (C) 2002 Elsevier Science Ltd. All rights reserved.},
	keywords = {actin, ACTIVATION, ACTOPHORIN, BINDING DOMAIN, CA2+, calcium, CAPPING PROTEIN, F-ACTIN, FAMILIAL AMYLOIDOSIS, FINNISH TYPE, gelsolin, IDENTIFICATION, MECHANISM, PLASMA GELSOLIN, REGULATION, severing},
	isbn = {0022-2836},
	url = {<Go to ISI>://000179825300011},
	author = {Choe, H. and Burtnick, L. D. and Mejillano, M. and Yin, H. L. and Robinson, R. C. and Choe, S.}
}
@article {4301,
	title = {Calcium binding by the N-terminal cellulose-binding domain from Cellulomonas fimi beta-1,4-glucanase CenC},
	journal = {Biochemistry},
	volume = {37},
	number = {37},
	year = {1998},
	note = {ISI Document Delivery No.: 125NRTimes Cited: 16Cited Reference Count: 33},
	month = {Sep},
	pages = {12772-12781},
	type = {Article},
	abstract = {The interaction of the N-terminal cellulose-binding domain, CBDN1, from Cellulomonas fimi beta-1,4-glucanase CenC with calcium was investigated using NMR spectroscopy and calorimetry. CBDN1 binds a single calcium ion with an equilibrium association constant of approximately 10(5) M-1 at 35 degrees C and pH 6.0. Binding is exothermic (-42 +/- 2 kJ mol(-1)) under these conditions and is accompanied by a small negative change in heat capacity (Delta C-p = -0.41 +/- 0.16 kJ mol(-1) K-1). From an NMR line shape analysis, the rate constants for calcium association and dissociation were found to be (5 +/- 7) x 10(7) s(-1) M-1 and (4.5 +/- 0.6) x 10(2) s(-1), respectively. The rapid association kinetics indicate that the calcium-binding site on CBDN1 is accessible and, to the first approximation, preformed. Based on patterns of chemical shift perturbations, and structural comparisons with the Bacillus sp. 1,3-1,4-beta-glucanases, the backbone carbonyl oxygens of Thr8, Gly30, and Asp 142 and a side chain carboxyl oxygen of Asp 142 are postulated to form the calcium-binding site of CBDN1. Consistent with the calcium-independent affinity of CBDN1 for cellopentaose, this exposed site is located on the face of CBDN1 opposite to that forming the oligosaccharide-binding cleft. The midpoint denaturation temperature of CBDN1 is increased by approximately 8 degrees C at pH 6.0 in the presence of saturating amounts of calcium, confirming that metal ion binding is thermodynamically linked to native-state stability.},
	keywords = {4-GLUCANOHYDROLASE, AFFINITY, CA2+, CRYSTAL-STRUCTURE, GLUCANASES, NUCLEAR-MAGNETIC-RESONANCE, RESOLUTION, SPECTROSCOPY, THERMODYNAMICS, THERMOSTABILITY},
	isbn = {0006-2960},
	url = {<Go to ISI>://000076244100011},
	author = {Johnson, P. E. and Creagh, A. L. and Brun, E. and Joe, K. and Tomme, P. and Haynes, C. A. and McIntosh, L. P.}
}
