2007
DOI: 10.1016/j.febslet.2007.01.031
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Calcium‐induced conformational changes in the amino‐terminal half of gelsolin

Abstract: Gelsolin is an actin-binding protein that is regulated by the occupancy of multiple calcium-binding sites. We have studied calcium induced conformational changes in the G1-2 and G1-3 sub-domains, and report the binding affinities for the three type II sites. A new probe for G3 has been produced and a K d of 5 lM has been measured for calcium in the context of G1-3. The two halves of gelsolin, G1-3 and G4-6 bind weakly with or without calcium, suggesting that once separated by apoptotic proteolysis, G1-3 and G4… Show more

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Cited by 8 publications
(6 citation statements)
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“…Reported calcium‐binding affinities for the type‐2 sites of gelsolin range from 0.2 to 600 μM, for example, K d = 600 μM in G1 [Zapun et al, ], K d = 0.7 μM in G2 [Chen et al, ], unknown K d for G3, K d = 1.8 μM in G4 [Pope et al, ], K d = 100 μM in G5 [Khaitlina et al, ], and K d = 0.2 μM in G6 [Pope et al, ], suggesting that the domains may bind calcium sequentially with increasing calcium concentrations, thus widening the range of calcium concentration to which the protein can respond and fine‐tune its activity. However, one must remember that the local environment modulates the response of this calcium‐sensing domain as evidenced by the variation in the measured K d values depending on whether a given domain is studied in isolation, or in the context of other domains, activators, or in the presence of the target protein, actin [Pope et al, ; Zapun et al, ; Chen et al, ; Chumnarnsilpa et al, ; Roustan et al, ]. Therefore, subtleties of the calcium‐binding process, such as cooperativity or dependence on binding partners, may be obscured in these studies.…”
Section: The Gelsolin Domainmentioning
confidence: 99%
“…Reported calcium‐binding affinities for the type‐2 sites of gelsolin range from 0.2 to 600 μM, for example, K d = 600 μM in G1 [Zapun et al, ], K d = 0.7 μM in G2 [Chen et al, ], unknown K d for G3, K d = 1.8 μM in G4 [Pope et al, ], K d = 100 μM in G5 [Khaitlina et al, ], and K d = 0.2 μM in G6 [Pope et al, ], suggesting that the domains may bind calcium sequentially with increasing calcium concentrations, thus widening the range of calcium concentration to which the protein can respond and fine‐tune its activity. However, one must remember that the local environment modulates the response of this calcium‐sensing domain as evidenced by the variation in the measured K d values depending on whether a given domain is studied in isolation, or in the context of other domains, activators, or in the presence of the target protein, actin [Pope et al, ; Zapun et al, ; Chen et al, ; Chumnarnsilpa et al, ; Roustan et al, ]. Therefore, subtleties of the calcium‐binding process, such as cooperativity or dependence on binding partners, may be obscured in these studies.…”
Section: The Gelsolin Domainmentioning
confidence: 99%
“…Figure 2A to 2B) and a strand from the β-sheet in G2 is removed with its subsequent reattachment to the β-sheet in G1, thus creating a new interface between G2 and G3 (Figure 2B) (Nag et al, 2009). Binding of calcium to the type 2 binding sites in the other domains stabilizes gelsolin in its open, active conformation (Figure 2B) (Ashish et al, 2007, Lueck et al, 2000, Roustan et al, 2007). …”
Section: The Multiple Structures Of Full-length Gelsolinmentioning
confidence: 99%
“…The structural and functional data from the last few decades have suggested that the actin filament-depolymerization activity of gelsolin resides in its N-terminal region, and the N-terminal half (G1-G3) of the molecule can depolymerize filamentous actin as well as cap the barbed end in a calciumindependent but PIP 2 -sensitive manner (6 -10). Despite the lack of absolute control of the depolymerizing activity of G1-G3 by Ca 2ϩ , these divalent ions do regulate the structure of the N-terminal half of gelsolin as evident from dynamic light scattering and fluorescence studies and analysis of its crystal structure (7,11,12). The fluorescence-based kinetic studies have also shown that the Ca 2ϩ binding-triggered conformational changes in G1-G3 enhance its interaction with F-actin, as well as increase its F-actin depolymerizing efficiency.…”
mentioning
confidence: 99%