Neither the retinal ring nor the ring double bond is required for proton pumping in bacteriorhodopsin: acyclic retinal bacterioopsin analogs

Crouch, Rosalie K.; Or, Yat Sun; Ghent, Shawn; Chang, Chung Ho; Govindjee, Rajni; Ebrey, Thomas G.; Callender, Robert; Pande, A.

doi:10.1021/ja00338a070

Cited by 16 publications

(14 citation statements)

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“…This reconstitution behavior is similar to that of BR apoprotein with ring desmethyl analogues (Gartner et al, 1983;Courtin et al, 1987) and acyclic retinal analogues (J. Rao et al, 1985;Crouch et al, 1984) but differs from the behavior of bovine opsin (Crouch and Or, 1983) whose regenerability is sensitive to ring modifications (Kropf et al, 1973). The absorption maxima of SR-I analogues are shifted to longer wavelengths compared with those of corresponding model protonated Schiff bases measured as previously reported (Arnaboldi et al, 1979) (Table 1).…”

Section: Resultssupporting

confidence: 69%

“…Studies with modified conjugated systems and fl-ionone ring/ polyene chain conformations (Baselt et al, 1989) have shown that the steric and electrostatic properties of the retinal binding sites in SR-I and BR have been conserved despite their different functions. Ring-modified retinal analogues have been used to study the role of the ,3-ionone ring in BR and rhodopsin (Gartner et al, 1983;Courtin et al, 1987;Crouch and Or, 1983;Crouch et al, 1984;Kropf et al, 1973). These studies showed specific interactions between ring methyls and the protein binding site are essential for bovine rhodopsin but not for BR to form stable pigments, and that BR proton pumping is not sensitive to ring portion modifications.…”

Section: Introductionmentioning

confidence: 99%

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Effects of modifications of the retinal beta-ionone ring on archaebacterial sensory rhodopsin I

Yan¹,

Takahashi²,

McCain³

et al. 1990

Biophysical Journal

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Ring desmethyl and acyclic analogues of all-trans retinal were incorporated into the apoprotein of the phototaxis receptor sensory rhodopsin I (SR-I) in Halobacterium halobium membranes. All modified retinals generate SR-I analogue pigments which exhibit "opsin shifts," i.e., their absorption spectra are shifted to longer wavelengths compared with model protonated Schiff bases of the same analogues. Each SR-I pigment analogue exhibits cyclic photochemical reactions as monitored by flash spectroscopy, but the analogue photocycles differ from that of native SR-I by exhibiting pronounced biphasic recovery of flash-induced absorption changes and abnormal flash-induced absorption difference spectra. Despite perturbations in the photochemical properties, the SR-I pigment analogues are capable of both attractant (single photon) and repellent (two photon) phototaxis signaling in cells. Our interpretation is that the hydrophobic ring substituents interact with the binding pocket to maintain the correct configuration for native SR-I absorption and photochemistry, but these interactions are not essential for the physiological function of SR-I as a dual attractant/repellent phototaxis receptor. These results support the conclusion emerging from several studies that the photoactivation process that triggers the conformation changes of SR-I and the related proton pump bacteriorhodopsin is conserved despite the different biological functions of their photoactivation.

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Section: Resultssupporting

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Effects of modifications of the retinal beta-ionone ring on archaebacterial sensory rhodopsin I

Yan¹,

Takahashi²,

McCain³

et al. 1990

Biophysical Journal

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“…The chromophore binding site of bacteriorhodopsin is specific for the all-trans and 13-cis isomers of retinal (1) (Kohl & Sperling, 1979). We have previously shown that the cyclohexyl ring of retinal is not required for pigment formation, as acyclic retináis such as 2-4 can form stable pigments with bacterioopsin (Crouch et al, 1984). These results are in agreement with experiments showing that bacterioopsin does not have a specific cyclohexyl ring binding site (Towner et al, 1981).…”

supporting

confidence: 88%

The effect of variation of retinal polyene side-chain length on formation and function of bacteriorhodopsin analog pigments

Zingoni¹,

Or²,

Crouch³

et al. 1986

Biochemistry

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The effect of the length of the retinal polyene side chain on bacterioopsin pigment formation and function has been investigated with two series of synthetic retinal analogues. Cyclohexyl derivatives with polyene chains one carbon longer and one or more carbons shorter than retinal and linear polyenes with no ring have been synthesized and characterized. Compounds of six carbons or less in the polyene chain form pigments very poorly or not at all with bacterioopsin. Compounds containing at least seven carbons in the chain are found to form reasonably stable bacterioopsin pigments that show a small shift in absorbance on irradiation. However, photocycling and proton photorelease are not detected. The analogue with nine carbons in the polyene chain (one less than retinal) forms a stable pigment with an M-type intermediate but demonstrates reduced amounts of photocycling and light-activated proton release. The analogue with a polyene chain identical with that of retinal, but containing no ring, forms a pigment that shows both an efficient light-activated proton photocycle and release. The pigment containing the chromophore with the polyene chain one carbon longer than retinal is likewise fully active. We thus conclude that the length of the polyene chain must be at least 9 carbons for the formation of a stable pigment that photocycles and must be 10 carbons for both the photocycle and light-activated proton release to have a high quantum efficiency.

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“…We could not detect any pigment formation with all‐ trans phenyl retinal (PHE). The lack of a stable AR3:PHE pigment indicates that this analog cannot be stably contained in the retinal binding pocket of AR3, most probably due to the absence of methyl groups on the phenyl ring, which strongly contribute to correct positioning and stabilization in the retinal binding pocket . This mirrors results obtained with GR, which does not appear to bind PHE, and is in contrast to PR, which forms a stable blueshifted PHE pigment .…”

Section: Resultssupporting

confidence: 60%

Redshifted and Near‐infrared Active Analog Pigments Based upon Archaerhodopsin‐3

Ganapathy

Kratz

Chen

et al. 2019

Photochem & Photobiology

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Archaerhodopsin-3 (AR3) is a member of the microbial rhodopsin family of hepta-helical transmembrane proteins, containing a covalently bound molecule of all-trans retinal as a chromophore. It displays an absorbance band in the visible region of the solar spectrum (kmax 556 nm) and functions as a light-driven proton pump in the archaeon Halorubrum sodomense. AR3 and its mutants are widely used in neuroscience as optogenetic neural silencers and in particular as fluorescent indicators of transmembrane potential. In this study, we investigated the effect of analogs of the native ligand all-trans retinal A1 on the spectral properties and proton-pumping activity of AR3 and its single mutant AR3 (F229S). While, surprisingly, the 3-methoxyretinal A2 analog did not redshift the absorbance maximum of AR3, the analogs retinal A2 and 3-methylamino-16-nor-1,2,3,4-didehydroretinal (MMAR) did generate active redshifted AR3 pigments. The MMAR analog pigments could even be activated by near-infrared light. Furthermore, the MMAR pigments showed strongly enhanced fluorescence with an emission band in the near-infrared peaking around 815 nm. We anticipate that the AR3 pigments generated in this study have widespread potential for near-infrared exploitation as fluorescent voltage-gated sensors in optogenetics and artificial leafs and as proton pumps in bioenergy-based applications.

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Neither the retinal ring nor the ring double bond is required for proton pumping in bacteriorhodopsin: acyclic retinal bacterioopsin analogs

Cited by 16 publications

References 1 publication

Effects of modifications of the retinal beta-ionone ring on archaebacterial sensory rhodopsin I

Effects of modifications of the retinal beta-ionone ring on archaebacterial sensory rhodopsin I

The effect of variation of retinal polyene side-chain length on formation and function of bacteriorhodopsin analog pigments

Redshifted and Near‐infrared Active Analog Pigments Based upon Archaerhodopsin‐3

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