@article {2546,
	title = {Ca2+ binding by domain 2 plays a critical role in the activation and stabilization of gelsolin},
	journal = {Proceedings of the National Academy of Sciences of the United States of America},
	volume = {106},
	number = {33},
	year = {2009},
	note = {ISI Document Delivery No.: 484WETimes Cited: 5Cited Reference Count: 30Nag, Shalini Ma, Qing Wang, Hui Chumnarnsilpa, Sakesit Lee, Wei Lin Larsson, Marten Kannan, Balakrishnan Hernandez-Valladarez, Maria Burtnick, Leslie D. Robinson, Robert C.},
	month = {Aug},
	pages = {13713-13718},
	type = {Article},
	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 Ca2+ 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 Ca2+ 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.},
	keywords = {actin, AMYLOIDOGENESIS, biosynthesis, calcium, calcium activated, calcium dependent, FAMILIAL AMYLOIDOSIS, IDENTIFICATION, PLASMA GELSOLIN, PROTEIN, SITE, TERMINAL HALF, TIRF},
	isbn = {0027-8424},
	url = {<Go to ISI>://000269078700018},
	author = {Nag, S. and Ma, Q. and Wang, H. and Chumnarnsilpa, S. and Lee, W. L. and Larsson, M. and Kannan, B. and Hernandez-Valladarez, M. and Burtnick, L. D. and Robinson, R. C.}
}
@article {813,
	title = {Structure of the N-terminal half of gelsolin bound to actin: roles in severing, apoptosis and FAF},
	journal = {Embo Journal},
	volume = {23},
	number = {14},
	year = {2004},
	note = {ISI Document Delivery No.: 847NBTimes Cited: 41Cited Reference Count: 59},
	month = {Jul},
	pages = {2713-2722},
	type = {Article},
	abstract = {The actin filament-severing functionality of gelsolin resides in its N-terminal three domains (G1 - G3). We have determined the structure of this fragment in complex with an actin monomer. The structure reveals the dramatic domain rearrangements that activate G1 - G3, which include the replacement of interdomain interactions observed in the inactive, calcium-free protein by new contacts to actin, and by a novel G2 - G3 interface. Together, these conformational changes are critical for actin filament severing, and we suggest that their absence leads to the disease Finnish-type familial amyloidosis. Furthermore, we propose that association with actin drives the calcium-independent activation of isolated G1 G3 during apoptosis, and that a similar mechanism operates to activate native gelsolin at micromolar levels of calcium. This is the first structure of a filament-binding protein bound to actin and it sets stringent, high-resolution limitations on the arrangement of actin protomers within the filament.},
	keywords = {5-BISPHOSPHATE, actin, AMYLOIDOSIS-FINNISH TYPE, apoptosis, BINDING-SITE, CA2+ REGULATION, calcium, CRYSTAL-STRUCTURE, crystallographic structure, F-ACTIN, FAMILIAL AMYLOIDOSIS, FILAMENT BARBED ENDS, gelsolin, PHOSPHATIDYLINOSITOL 4, PLASMA GELSOLIN, X-RAY},
	isbn = {0261-4189},
	url = {<Go to ISI>://000223398800002},
	author = {Burtnick, L. D. and Urosev, D. and Irobi, E. and Narayan, K. and Robinson, R. C.}
}
@article {697,
	title = {Activation in isolation: exposure of the actin-binding site in the C-terminal half of gelsolin does not require actin},
	journal = {Febs Letters},
	volume = {552},
	number = {2-3},
	year = {2003},
	note = {ISI Document Delivery No.: 726DKTimes Cited: 15Cited Reference Count: 23},
	month = {Sep},
	pages = {82-85},
	type = {Article},
	abstract = {Gelsolin requires activation to carry out its severing and capping activities on F-actin. Here, we present the structure of the isolated C-terminal half of gelsolin (G4-G6) at 2.0 resolution in the presence of Ca2+ ions. This structure completes a triptych of the states of activation of G4-G6 that illuminates its role in the function of gelsolin. Activated G4-G6 displays an open conformation, with the actin-binding site on G4 fully exposed and all three type-2 Ca2+ sites occupied. Neither actin nor the type-1 Ca2+, which normally is sandwiched between actin and G4, is required to achieve this conformation. (C) 2003 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.},
	keywords = {actin, calcium-activation, COMPLEX, DOMAINS, F-ACTIN, gelsolin, PLASMA GELSOLIN, REGULATORY PROTEIN, TRANSFORMATION},
	isbn = {0014-5793},
	url = {<Go to ISI>://000185583000002},
	author = {Narayan, K. and Chumnarnsilpa, S. and Choe, H. and Irobi, E. and Urosev, D. and Lindberg, U. and Schutt, C. E. and Burtnick, L. D. and Robinson, R. C.}
}
@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 {4646,
	title = {Domain movement in gelsolin: A calcium-activated switch},
	journal = {Science},
	volume = {286},
	number = {5446},
	year = {1999},
	note = {ISI Document Delivery No.: 261HHTimes Cited: 94Cited Reference Count: 18},
	month = {Dec},
	pages = {1939-1942},
	type = {Article},
	abstract = {The actin-binding protein gelsolin is involved in remodeling the actin cytoskeleton during growth-factor signaling, apoptosis, cytokinesis, and cell movement. Calcium-activated gelsolin severs and caps actin filaments, The 3.4 angstrom x-ray structure of the carboxyl-terminal half of gelsolin (G4-G6) in complex with actin reveals the basis for gelsolin activation. Calcium binding induces a conformational rearrangement in which domain G6 is flipped over and translated by about 40 angstroms relative to G4 and G5. The structural reorganization tears apart the continuous beta sheet core of G4 and G6. This exposes the actin-binding site on G4, enabling severing and capping of actin filaments to proceed.},
	keywords = {actin, BINDING-SITE, COMPLEX, FILAMENT, IDENTIFICATION, PLASMA GELSOLIN},
	isbn = {0036-8075},
	url = {<Go to ISI>://000084003400047},
	author = {Robinson, R. C. and Mejillano, M. and Le, V. P. and Burtnick, L. D. and Yin, H. L. and Choe, S.}
}
