The Gecko visual pigment: The anion hypsochromic effect

Crescitelli, Frederick; Karvaly, Béla

doi:10.1016/0042-6989(91)90202-g

Cited by 10 publications

(11 citation statements)

References 20 publications

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“…Comparison of the mouse green pigment amino acid sequence with the sequences of other long-wave pigments suggests that a loss of chloride sensitivity (23)(24)(25)(26)(27) could account for the blue shift produced by sequence differences in the second extracellular loop. The mouse green pigment is the only member of the long-wave subfamily of visual pigments sequenced to date that does not have a histidine at position 197 in the second extracellular loop, a residue which has been shown by site-directed mutagenesis to mediate a chloridedependent red shift of 30 nm in the human long-wave family (28).…”

Section: Resultsmentioning

confidence: 99%

“…Fig. 2f shows that the mouse green pigment differs from other pigments in the long-wave subfamily in that its spectrum is not changed upon replacement of chloride by iodide, an anion that does not produce a chloride-type red shift (23)(24)(25)(26)(27). To determine whether this difference in spectral behavior could be attributed solely to a difference at residue 197, we examined the properties of single amino acid substitution mutations at this position.…”

Section: Resultsmentioning

confidence: 99%

“…In keeping with these models, sequence comparisons and spectroscopic studies of site-directed mutants have identified a glutamate counterion that is present in all vertebrate photoreceptor pigments sequenced to date and is required for protonation of the retinylidene Schiff base (16)(17)(18), and three positions where increases in side-chain polarity lead to red shifts of 5-14 nm that together account for most of the variation in absorption maxima among previously characterized members of the longwave subfamily (19)(20)(21)(22). A third red-shifting mechanism involves an interaction between chloride and a histidine in the second putative extracellular loop in members of the longwave pigment subfamily (23)(24)(25)(26)(27)(28); the mechanistic basis of the chloride effect is unclear.…”

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confidence: 99%

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Mechanisms of spectral tuning in the mouse green cone pigment

Sun

Macke

Nathans

1997

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

184

153

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Diversification of cone pigment spectral sensitivities during evolution is a prerequisite for the development of color vision. Previous studies have identified two naturally occurring mechanisms that produce variation among vertebrate pigments by red-shifting visual pigment absorbance: addition of hydroxyl groups to the putative chromophore binding pocket and binding of chloride to a putative extracellular loop. In this paper we describe the use of two blue-shifting mechanisms during the evolution of rodent long-wave cone pigments. The mouse green pigment belongs to the long-wave subfamily of cone pigments, but its absorption maximum is 508 nm, similar to that of the rhodopsin subfamily of visual pigments, but blue-shifted 44 nm relative to the human red pigment, its closest homologue. We show that acquisition of a hydroxyl group near the retinylidene Schiff base and loss of the chloride binding site mentioned above fully account for the observed blue shift. These data indicate that the chloride binding site is not a universal attribute of long-wave cone pigments as generally supposed, and that, depending upon location, hydroxyl groups can alter the environment of the chromophore to produce either red or blue shifts.Visual pigments differ between species and between different photoreceptor cells within the same species in their wavelengths of maximal absorption. This diversity of visual pigment absorption spectra is determined by interactions between the 11-cis-retinal chromophore and the particular opsin to which it binds, or in rare instances by the alternate use of an 11-cis-dehydroretinal chromophore (1). Among vertebrate visual pigments that use 11-cis-retinal, absorption maxima have been identified throughout the wavelength interval from 360 nm (2, 3) to 570 nm (4). Sequencing of visual pigments from diverse species shows a limited range of wavelengths of maximal absorption among members of each of the three major branches of the visual pigment family: the short-wave subfamily absorbs maximally at wavelengths less than 500 nm, the rhodopsin subfamily absorbs maximally at wavelengths near 500 nm, and the long-wave subfamily absorbs at wavelengths greater than 500 nm (5-7).Experiments with retinal and its derivatives in solution have led to a number of plausible mechanisms for spectral tuning in visual pigments (8-11). The two photochemical properties of retinal that are most relevant are the shift in absorption maximum from 360 nm to 440 nm upon formation of a protonated Schiff base (12, 13) and the increase in -electron delocalization and the concomitant change in dipole moment that accompanies photoexcitation (14,15). Therefore, amino acids from the apoprotein that alter the polarity, polarizability, or charge density around either the conjugated -electron system or the retinylidene Schiff base would be expected to shift the absorption spectrum of the pigment. In keeping with these models, sequence comparisons and spectroscopic studies of site-directed mutants have identified a glutamate counterio...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Mechanisms of spectral tuning in the mouse green cone pigment

Sun

Macke

Nathans

1997

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

184

153

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“…A straightforward method is the isolation of cone pigments from the retina of organisms of interest. This method can only reasonably be applied to retinas where cone cells are abundant, for example chicken [1,2] and lizard (Gecko gecko) [3][4][5]. In most higher vertebrates, however, the rod cells by far outnumber the cones and isolation of native cone pigments from these species has not been reported.…”

Section: Introductionmentioning

confidence: 99%

Functional expression of human cone pigments using recombinant baculovirus: compatibility with histidine tagging and evidence for N‐glycosylation

Vissers

DeGrip

1996

FEBS Letters

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Mammalian color vision is mediated by fight-sensitive pigments in retinal cone cells. Biochemical studies on native mammalian cone visual pigments are seriously hampered by their low levels and instability. We describe a novel approach for their functional expression, employing the baculovirus system in combination with histidine tagging to allow future purification and structural analysis. The human red and green cone pigments are produced in relatively large amounts and can be detected by immunocytochemistry as well as by immunoblotting. Histidine tagging has no significant effect on the absorhance maxima. The first evidence is presented that these pigments are N-glycosylated.

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“…Evidence for this possibility was first provided for the gecko P521 pigment (10)(11)(12), then for chicken iodopsin (13,14), and recently for the red-absorbing cone pigment in frog (15). For example, when the gecko pigment was studied in a Cl--free environment, its Amax was found to be '500 nm; when Clwas added, Amax shifted to the native value of 521 nm (10,11). A similar Cl--induced shift from 520 to 565 nm was found in chicken iodopsin (13,14).…”

mentioning

confidence: 99%

Anion sensitivity and spectral tuning of cone visual pigments in situ.

Kleinschmidt

Hárosi

1992

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

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We tested the effect of anions on the absorbance spectrum of native visual pigments as measured by microspectrophotometry in individual cone outer segments of four species of fish and one species of amphibian. In all species tested, the long-wavelength-absorbing cone pigments were anion sensitive, and their A.. could be tuned over a range of 55 nm depending on the identity of the anion present. Cl-and Br-were the only anions that produced native pigment spectra by red shifting A.. from its value under anion-free conditions. Lyotropic anions such as NO-, SCN-, BF4, and ClIO caused substantial and graded blue shifts of A... The apparent Kd of binding sites on the pigment for Cl-and for CIO4 was -2 mM. Taken together with previous findings on three visual pigments from the reptilian, avian, and amphibian classes, our results support the hypothesis that all long-wavelength-absorbing vertebrate visual pigments are spectrally tuned in part through the binding of a chloride ion. We propose that the site of anion tuning is near the protonated Schiff base of the chromophore, whose counterion may be complex and include Cl-as an exchangeable anion. This counterion configuration may resemble the one present in the light-driven Cl-pump halorhodopsin.Color vision in vertebrates is based on sets of two, three, or four different photopigments that reside in separate classes of cone photoreceptors. The wavelength of peak absorbance (Amax) of these pigments ranges from the UV (360 nm) to the far red (635 nm). All vertebrate visual pigments are integral membrane proteins and contain 11-cis-retinal or 11-cisdehydroretinal as the chromophore that is covalently bound through a Schiffbase linkage to a lysine residue on the protein (opsin) moiety ofthe pigment (1). Although great progress has been made in recent years in unraveling the structure of visual pigments, the molecular basis of spectral tuning is still only incompletely understood.A variety of mechanisms have been invoked to account for photopigment tuning (for reviews, see refs. 2 and 3). For example, protonation of the retinal Schiff base shifts Amax from 360 to 430 nm (4). Blue-absorbing pigments may contain an unperturbed chromophore behaving much like a protonated retinal Schiff base in a nonpolar solvent (5). Closer interaction of the chromophore with the protein perturbs the electronic structure of the chromophore and results in an additional red shift of Am,,,. This shift is commonly called the "opsin shift" and very likely comprises multiple components. For example, Amax is extremely sensitive to the charge environment provided by the counterion, which is paired with the protonated Schiff base (3). A decreased interaction between protonated Schiff base and counterion, perhaps caused by an increased distance between the two, may be responsible for the opsin shift in green-absorbing rhodopsins (Amax, "500 nm). Amino acid side chains, which form the hydrophobic binding pocket for the chromophore, also can interact with and perturb the chromophore. In fact, much ...

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The Gecko visual pigment: The anion hypsochromic effect

Cited by 10 publications

References 20 publications

Mechanisms of spectral tuning in the mouse green cone pigment

Mechanisms of spectral tuning in the mouse green cone pigment

Functional expression of human cone pigments using recombinant baculovirus: compatibility with histidine tagging and evidence for N‐glycosylation

Anion sensitivity and spectral tuning of cone visual pigments in situ.

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