Direct zinc binding to purified rhodopsin and disc membranes

Shuster, Terrence A.; Nagy, Ágnes; Conly, D C; Farber, Débora B.

doi:10.1042/bj2820123

Cited by 69 publications

(37 citation statements)

References 22 publications

(21 reference statements)

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“…Although these results show that fusion proteins containing the VSP metal-binding domain, the VSP metal-binding domain alone, or portions of this domain (1-5, 7, 8.1, 9.1 (32) in CRP170, adpribose in VSPH7 (32), and the iron binding motifs CX6CX2CX5C in CRP170 (34) and CX2CX16CX13C in TSA417 (35 (24,25,31). The surface location of proteins containing similar motifs is unprecedented (26-28, 30, 36-44).…”

Section: Resultsmentioning

confidence: 99%

Variant-specific surface proteins of Giardia lamblia are zinc-binding proteins.

Nash

Mowatt

1993

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

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GiardYa lamblia undergoes surface antigenic variation. The variant-specific surface proteins (VSPs) are a distinct family of cysteine-rich proteins. Characteristically, cysteine residues occur mostly as CXXC tetrapeptides. Four of the reported five VSPs contain a putative metal-binding domain that resembles other metal-binding motifs; the fifth is closely related but lacks an essential histidine. Three different native VSPs bound Zn2+. Co2+, Cu2+, and Cd2+ inhibited Zn2+ binding. Analysis of recombinant VSP fusion proteins showed that the putative binding motif bound Zn2+. Surprisingly, peptide fragments from other regions of the VSP contain numerous CXXCX,CXXC motifs that also bound Zn2+. Analysis of deduced amino acid sequences showed well-conserved CXXC spacing in three out of five VSPs, suggesting conservation of structure despite amino acid sequence divergence. The function of VSPs is unknown, but by binding Zn2+ or other metals in the intestine, VSPs may contribute to Zn2+ malnutrition or inhibition of metal-dependent intestinal enzymes, which would lead to malabsorption, a well-known consequence of giardiasis.

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Section: Resultsmentioning

confidence: 99%

Variant-specific surface proteins of Giardia lamblia are zinc-binding proteins.

Nash

Mowatt

1993

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

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“…This binding occurs in the dark and it increases upon illumination of the protein (27). Also, previous reports indicated that Zn 2ϩ enhanced azido-[␣-32 P]ATP binding to rat ROS, suggesting a structural effect of Zn 2ϩ on rhodopsin (29).…”

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confidence: 98%

“…These include the dopamine transporter (24) Previous reports showed direct Zn 2ϩ binding to rhodopsin, both in ROS membranes and in detergent-solubilized-purified protein systems, by means of 65 Zn competition binding experiments, indicating that there may be coordination sites for Zn 2ϩ in native rhodopsin (27). This binding occurs in the dark and it increases upon illumination of the protein (27).…”

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confidence: 99%

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Zinc-induced Decrease of the Thermal Stability and Regeneration of Rhodopsin

Valle

Ramon

Cañavate

et al. 2003

Journal of Biological Chemistry

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Zinc is present at high concentrations in the photoreceptor cells of the retina where it has been proposed to play a role in the visual phototransduction process. In order to obtain more information about this role, the study of the effect of zinc on several properties of the visual photoreceptor rhodopsin has been investigated. A specific effect of Zn 2؉ on the thermal stability of rhodopsin, obtained from bovine retinas and solubilized in dodecyl maltoside detergent, in the dark is reported. Rhodopsin is the photoreceptor protein of the vertebrate retina (1-3) belonging to the G-protein-coupled receptor (GPCR) 1 superfamily (4 -6). It is the main protein component of the rod outer segments (ROS) of the retinal photoreceptor cells, and its easy isolation from bovine retinas has made of this receptor a widely used model for the GPCR superfamily. Rhodopsin is a key molecule in the biochemistry of vision and alterations in its sequence have been associated with retinal disease. In particular, a high number of mutations in the opsin gene have been associated with the autosomal form of the retinal degenerative disease retinitis pigmentosa (7,8). A number of factors have been proposed to be related to retinal function, and among them a possible role for Zn 2ϩ in the retina and its metabolism has been proposed (9). Zn 2ϩ is present at particularly high concentrations in the retina (10) being a component of the disc membranes in the rod outer segments of the photoreceptor cells (11). Zn 2ϩ has been histochemically localized to ROS (12) and it has been shown to copurify with ROS proteins as well (13). Despite this presence, the role of Zn 2ϩ in the visual cycle and specifically in its interaction with rhodopsin remains unclear.Zn 2ϩ is required for the function of numerous proteins, serving both as a part of the active site in, for example, metalloenzymes, and acting to stabilize protein domains, such as the Zn 2ϩ fingerbinding motif in transcription factors (14, 15). The structure of many Zn 2ϩ -binding sites is known from x-ray crystallography of Zn 2ϩ -binding proteins and, thus, the geometry of the interaction between Zn 2ϩ and different coordinating residues is well characterized (14, 15). This, together with the small size of the zinc (II) ion, makes artificially generated Zn 2ϩ -binding sites a highly useful approach for probing structure-function relationships in proteins. In GPCRs, for example, construction of bis-His Zn 2ϩ -binding sites has led to important information about both the organization of the transmembrane helices and their movements during receptor activation to be obtained (16 -22). Therefore, engineered Zn 2ϩ binding sites created by site-directed mutagenesis is an interesting tool for probing intramolecular interactions in these types of receptors (23). Particularly in the case of rhodopsin, important structural information about helical orientation, connectivities, and the conformational change upon light activation, has been obtained from engineered Zn 2ϩ -binding sites in this visual photore...

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“…Zn 2ϩ occurs at high concentrations in the retina (Grahn et al, 2001) and zinc deficiency in humans can lead to vision-related disorders such as poor dark adaptation, night blindness, and retinal degeneration (Ugarte and Osborne, 2001). The role of Zn 2ϩ in vision probably relates to rhodopsin because it directly associates with this receptor (Shuster et al, 1992;Stojanovic et al, 2004) and increases its phosphorylation (Shuster et al, 1996). Furthermore, the presence and absence of Zn 2ϩ changes the pattern of thermal bleaching and regeneration of rhodopsin by 11-cis-retinal (del Valle et al, 2003;Stojanovic et al, 2004).…”

Section: E Detecting How Intramolecular Interactions Of a G Protein-mentioning

confidence: 99%