Comparison of the O640 photo‐intermediate and acid‐induced species in membrane patches from Halobacterium halobium S9 and R1mW strains

Lam, Eric; Fry, Ian V.; Packer, Lester; Mukohata, Yasuo

doi:10.1016/0014-5793(82)80714-x

Cited by 12 publications

(5 citation statements)

References 17 publications

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“…Data by other groups (Chang et al, 1985(Chang et al, , 1986) and ourselves (Duñach et al, 1987a,b) indicate that BR carboxyl groups are involved in the high-affinity cation binding sites of purple membrane. However, a contribution of phospholipid head groups to the sites is suggested by the influence of the lipid environment on the purple-blue transition (Lind et al, 1981;Lam et al, 1982;Hiraki et al, 1984) and by the recent observation that cations do not affect this transition in partially delipidated purple membrane (Szundi & Stoeckenius, 1987). Our NMR data are consistent with this proposition, though we are aware that these do not constitute a definitive proof.…”

Section: Discussionsupporting

confidence: 69%

Phosphorus-31 NMR study of the interaction of cations with purple membrane and of the purple-blue transition

Roux¹,

Seigneuret²,

Rigaud³

1988

Biochemistry

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Section: Discussionsupporting

confidence: 69%

Phosphorus-31 NMR study of the interaction of cations with purple membrane and of the purple-blue transition

Roux¹,

Seigneuret²,

Rigaud³

1988

Biochemistry

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“…Since the Y185F mutation increases the pKa for the acid-induced blue transition from 2.7 to 3.7, the O-like species which forms at higher pH cannot be attributed to this low-pH acid-induced blue form of Y18 5 F. However, the acidinduced blue membrane consists of a mixture of two forms containing all-trans and 13-cis isomers of retinal (Fischer & Oesterhelt, 1979;Mowery et al, 1979;Fahmy & Siebert, 1990). Although it is unlikely that the the O intermediate is equivalent to the acid-induced blue membrane (Smith & Mathies, 1985) as previously suggested (Moore et al, 1978;Edgerton et al, 1978;Lam et al, 1982), the possibility remains that the all-trans component of the acid-induced blue membrane (BM7) is similar to both the O intermediate and the O-like species we observe here. In fact, FTIR difference spectra for pH titration of wild-type bR between the purple and acid-induced blue form (Marrero & Rothschild, 1987) and more recent studies on light-adapted blue membrane (Fahmy & Siebert, 1990) reveal similarities in the vibrational spectra between the all-trans species formed at low pH and the O-like species we observe at higher pH in Y185F (He et al, 1993;Rath et al, 1993).…”

Section: Discussionmentioning

confidence: 68%

Static and time-resolved absorption spectroscopy of the bacteriorhodopsin mutant Tyr-185 .fwdarw. Phe: Evidence for an equilibrium between bR570 and an O-like species

Sonar¹,

Krebs²,

Khorana³

et al. 1993

Biochemistry

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The light-dark adaptation, photocycle kinetics, and acid-induced blue formation of the bacteriorhodopsin (bR) mutant Tyr-185-->Phe (Y185F) expressed in Halobacterium halobium have been investigated by both static and time-resolved visible absorption spectroscopy. Evidence is presented that a pH-dependent equilibrium exists between a bR570-like form (bRY185F570) and a red-shifted species in the light-adapted form of Y185F. In two related papers, we show that this species has vibrational features similar to the O intermediate. Key findings are that light adaptation causes formation of a purple species similar to bR570 and a second long-lived red-shifted species with a lambda max near 630 nm, well above the pH for the acid-induced blue transition. The concentration of the red-shifted species is pH- and salt-dependent, decreasing reversibly at high pH and high ionic strength. The dark-adapted state of Y185F also contains a small amount of the red-shifted species which is reversibly titratable. Dark adaptation is much slower than wild-type bR and causes a parallel decay of light-adapted bR and the red-shifted species. Time-resolved visible absorption spectroscopy reveals that the purple and the red-shifted species undergo separate photocycles. The purple species exhibits a relatively normal photocycle except for an increased rate of M formation kinetics. The red-shifted species has a photocycle involving a red-shifted K intermediate and a second longer lived intermediate possibly similar to N. The apparent absence of an O intermediate in the late photocycle of Y185F is attributed to cancellation by depletion bands due to the photoreacting red-shifted species.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…The 0-state of BR and BR605 are spectroscopically very similar when comparing their respective difference spectra with BR (Fischer and Oesterhelt, 1979;Lam et al, 1982). Both occur in all-trans configuration of their chromophores (Smith et al, 1983;Fischer and Oesterhelt, 1979) and for the 0-state it has recently been shown that Asp85 is protonated (Mueller et al, 1991) and releases the proton through the extracellular channel during the transition to BR in completion of the photocycle.…”

Section: Discussionmentioning

confidence: 90%

Photochemical conversion of the O-intermediate to 9-cis-retinal-containing products in bacteriorhodopsin films

Popp¹,

Wolperdinger²,

Hampp³

et al. 1993

Biophysical Journal

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The photochemical activity of the O-state was investigated in bacteriorhodopsin (BR) films containing wildtype BR at pH 6.5 in the presence of glycerol. The formation of a photoproduct of O with an absorption maximum at 490 nm and 9-cis-retinal configuration was found. This 490-nm product was named P and shows a slow thermal reaction into a compound with a maximal absorption at 380 nm which was named Q and contains free 9-cis-retinal in the proteins binding site. The photoproducts of O, i.e., P and Q, are very similar, or even identical, to those previously observed in blue membranes. Common to the O-state and blue membrane forms of bacteriorhodopsin is a protonated aspartic acid 85, and we suggest that it is the reduced negative charge around the Schiff base which is responsible for the 9-cis photoisomerization. The release of a proton from aspartic acid 85 is linked to the conversion of the O-state back to the initial state of BR. Therefore the conditions of low proton mobility in BR films containing glycerol favor the accumulation of the O-state. For optical and holographic applications such BR films are very attractive. It is possible to create photoproducts with red light which are thermally stable at room temperature and that can be photochemically erased. Dependent on the light composition both properties can be realized in the same sample material. This feature may bridge the gap between information processing and short-term and long-term storage of information with BR.

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Comparison of the O₆₄₀ photo‐intermediate and acid‐induced species in membrane patches from Halobacterium halobium S₉ and R₁mW strains

Cited by 12 publications

References 17 publications

Phosphorus-31 NMR study of the interaction of cations with purple membrane and of the purple-blue transition

Phosphorus-31 NMR study of the interaction of cations with purple membrane and of the purple-blue transition

Static and time-resolved absorption spectroscopy of the bacteriorhodopsin mutant Tyr-185 .fwdarw. Phe: Evidence for an equilibrium between bR570 and an O-like species

Photochemical conversion of the O-intermediate to 9-cis-retinal-containing products in bacteriorhodopsin films

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