EF-hand calcium-binding proteins

Lewit-Bentley, Anita; Réty, S.

doi:10.1016/s0959-440x(00)00142-1

Cited by 483 publications

(396 citation statements)

References 47 publications

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“…For these mutants, where only one EF hand was left intact, Ca 2ϩ EC 50 values were 34 Ϯ 9 M for EF1 ϩ 2 Ϫ 3 Ϫ , 6.1 Ϯ 0.1 M for EF1 Ϫ 2 ϩ 3 Ϫ , and 7.6 Ϯ 0.6 M for EF1 Ϫ 2 Ϫ 3 ϩ . The Ca 2ϩ sensitivities of EF1 Ϫ 2 ϩ 3 Ϫ or EF1 Ϫ 2 Ϫ 3 ϩ , lower than that of WT, suggest that mutation of either EF hand of the EF2,3 pair reduced the affinity of the remaining EF hand, as reported for other Ca 2ϩ -binding proteins (8,17). Hence, affinities of WT EF2 and EF3 are presumably higher than suggested by the Ca 2ϩ sensitivities of EF1 Ϫ 2 ϩ 3 Ϫ or EF1 Ϫ 2 Ϫ 3 ϩ mutants.…”

Section: Bright and Slodk Mutationsmentioning

confidence: 70%

“…The effect of N 26 D likely results from an increased EF1 affinity, consistent with the replacement of the polar Ca 2ϩ -binding asparagine residue by a negatively charged residue. The effect of E 35 G seems paradoxical, given that this mutation removes an essential Ca 2ϩ -binding side chain (8,17). This can be resolved by assuming that EF1 has lower Ca 2ϩ affinity than EF2 and EF3, and that E 35 G impairs EF1 contribution to the response to Ca 2ϩ .…”

Section: Bright and Slodk Mutationsmentioning

confidence: 99%

“…We found that EF hands have different Ca 2ϩ affinities, and all contribute to the variations of decay rate that determine the increase of luminescence intensity with [Ca 2ϩ ]. (16) affect residues conserved in other photoproteins (see the supporting information, which is published on the PNAS web site), located either in EF hands at canonical Ca 2ϩ -binding positions (8) or in their adjacent ␣-helices (Fig. 1A).…”

mentioning

confidence: 99%

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Calcium dependence of aequorin bioluminescence dissected by random mutagenesis

Tricoire¹,

Tsuzuki²,

Courjean³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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Aequorin bioluminescence is emitted as a rapidly decaying flash upon calcium binding. Random mutagenesis and functional screening were used to isolate aequorin mutants showing slow decay rate of luminescence. Calcium sensitivity curves were shifted in all mutants, and an intrinsic link between calcium sensitivity and decay rate was suggested by the position of all mutations in or near EF-hand calcium-binding sites. From these results, a low calcium affinity was assigned to the N-terminal EF hand and a high affinity to the C-terminal EF-hand pair. In WT aequorin, the increase of the decay rate with calcium occurred at constant total photon yield and thus determined a corresponding increase of light intensity. Increase of the decay rate was underlain by variations of a fast and a slow component and required the contribution of all three EF hands. Conversely, analyses of double EF-hand mutants suggested that single EF hands are sufficient to trigger luminescence at a slow rate. Finally, a model postulating that proportions of a fast and a slow light-emitting state depend on calcium concentration adequately described the calcium dependence of aequorin bioluminescence. Our results suggest that variations of luminescence kinetics, which depend on three EF hands endowed with different calcium affinities, critically determine the amplitude of aequorin responses to biological calcium signals.EF hand ͉ kinetics ͉ luminescence ͉ photoprotein ͉ transduction T he photoprotein aequorin is a stable luciferase intermediate formed from the reaction of the protein apoaequorin (luciferase) and the substrate coelenterazine (luciferin), which emits light upon Ca 2ϩ binding (1-5). Aequorin contains three EF-hand Ca 2ϩ -binding sites (6-8) located close to its N (EF1) or C terminus (EF2,3 pair). Aequorin mutagenesis and crystal structure suggest that these three EF hands indeed bind Ca 2ϩ , but their individual contribution to luminescence is still a matter of debate (9-13).The steep increase of luminescence intensity with [Ca 2ϩ ] makes aequorin a useful reporter of intracellular calcium signals (14). The formation of aequorin is a slow process (2), whereas the luminescence reaction is very fast and proceeds to completion in the continuous presence of Ca 2ϩ . The aequorin response thus occurs as a flash that decays exponentially and whose onset rate does not depend on [Ca 2ϩ ] (15). It has been observed early that the decay rate of this response increases with [Ca 2ϩ ], whereas the total light emitted (light integral) remains relatively constant (15). This suggests that the increase of luminescence intensity with [Ca 2ϩ ] is determined by variations of the decay rate but not of the light integral. In other words, the shorter the duration of the flash (i.e., the faster the decay), the larger the amplitude of the response (i.e., light intensity). However, the relationships among the intensity, the decay rate, and the integral of bioluminescence and their links to EF-hand occupancy have not been clearly established.To analyze the co...

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Section: Bright and Slodk Mutationsmentioning

confidence: 70%

Section: Bright and Slodk Mutationsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Calcium dependence of aequorin bioluminescence dissected by random mutagenesis

Tricoire¹,

Tsuzuki²,

Courjean³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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“…The data that are currently available support a structural role for the metal, which is not surprising given the extraordinary number and diversity of proteins in which it plays a central role in conferring structural stability (Kretsinger and Nelson 1976;Lewit-Bentley and Rety 2000;Strynadka and James 1989). The new structural information that's available showing the metal to be linked to Mn by carboxylate bridges is consistent with a structural function.…”

Section: Why Does the Oec Contain Ca 2+ ?mentioning

confidence: 82%

“…The signaling function of Ca 2+ is also essential as an intracellular ''second messenger'' that transduces signals received by the cell exterior (Bootman and Berridge 1995). In this system, the reversible binding of Ca 2+ (K d =~10 -6 -10 -7 M) to EF hand proteins (calmodulins, troponin C, calbindin, and so on (Strynadka and James 1989;Lewit-Bentley and Rety 2000)) provides a sensitive monitoring system, that couples cellular metabolism to signals arriving at the cell surface. Unfortunately, these functions and the wealth of structural and functional data derived from them provide little in the way of comparative information that can be used to sort out another major function of Ca 2+ , that of an essential cofactor of the inorganic ion complex (4Mn, Ca 2+ , Cl -) in PSII that oxidizes H 2 O to O 2 .…”

Section: Introductionmentioning

confidence: 99%

The PSII calcium site revisited

2007

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Oxidation of H 2 O by photosystem II is a unique redox reaction in that it requires Ca 2+ as well as Cl -as obligatory activators/cofactors of the reaction, which is catalyzed by Mn atoms. The properties of the binding site for Ca 2+ in this reaction resemble those of other Ca 2+ binding proteins, and recent X-ray structural data confirm that the metal is in fact ligated at least in part by amino acid side chain oxo anions. Removal of Ca 2+ blocks water oxidation chemistry at an early stage in the cycle of redox reactions that result in O-O bond formation, and the intimate involvement of Ca 2+ in this reaction that is implied by this result is confirmed by an ever-improving set of crystal structures of the cyanobacterial enzyme. Here, we revisit the photosystem II Ca 2+ site, in part to discuss the additional information that has appeared since our earlier review of this subject (van Gorkom HJ, Yocum CF In: Wydrzynski TJ, Satoh K (eds) Photosystem II: the light-driven water:plastoquinone oxidoreductase), and also to reexamine earlier data, which lead us to conclude that all S-state transitions require Ca 2+ .

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Parvalbumin

Nakayama

Kawasaki

Kretsinger

2004

Handbook of Metalloproteins

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Parvalbumin was the first EF‐hand protein to have been characterized and to have its crystal structure determined. This prototype consists of an α‐helix E (extended forefinger of a clenched right hand), loop around the Ca 2+ ion (clenched middle finger), and α‐helix F (extended thumb). Parvalbumin has provided a reference point for the analyses of 76 other subfamilies of proteins that contain 2 to 12 EF‐hands. Most, but not all, EF‐hands bind calcium. The Ca 2+ ion is almost always coordinated by seven oxygen atoms arranged in an approximate pentagonal bipyramid; usually one of the ligands is a carboxylate group that coordinates calcium with both its oxygen atoms. The affinities of EF‐hands for calcium range from p K d (Ca 2+ ) 6 to 8. The dissociation constant of parvalbumin for calcium ( K d ∼ 10 −8 M) reflects one of the highest affinities of all the EF‐hand proteins. All, or most, of the EF‐hand proteins bind calcium ∼10 4.0 more strongly than they bind the six‐coordinate magnesium. Most of this difference in affinity derives from the ∼10 3.4 greater on rate for calcium, which in turn derives from its faster dehydration rate. Parvalbumin functions in fast, white, skeletal muscle to soak up messenger calcium following a stimulus, thereby facilitating rapid relaxation. Whether it has an analogous function in neurons, thymus, or other tissues remains to be demonstrated. Most EF‐hand proteins change conformation upon binding calcium, thereby transducing the information content of a pulse of cytosolic messenger Ca 2+ ions. Although the binding of calcium to the two EF‐hands of monomeric parvalbumin is not (or only very weakly) cooperative, as is the case for other EF‐hand proteins, the interaction of a pair of EF‐hands is essential for the stability of these proteins. The angle between the two helices (E and F) of a single EF‐hand as well as the contact between the pair of EF‐hands is usually more open following binding of calcium, thereby exposing hydrophobic side chains. However, a survey of the known structures of all known EF‐hands proteins does not reveal a bimodal closed, open set of conformations reflecting either binding of calcium and/or binding of targets for those EF‐hand proteins involved in information transduction.

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EF-hand calcium-binding proteins

Cited by 483 publications

References 47 publications

Calcium dependence of aequorin bioluminescence dissected by random mutagenesis

Calcium dependence of aequorin bioluminescence dissected by random mutagenesis

The PSII calcium site revisited

Parvalbumin

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