Anomalous pH Effect of Blue Proteorhodopsin.
J Phys Chem Lett
; 3(7): 800-4, 2012 Apr 05.
Article
em En
| MEDLINE
| ID: mdl-26286400
ABSTRACT
Proteorhodopsin (PR) is a light-driven proton pump found in marine bacteria, and thousands of PRs are classified into blue-absorbing PR (B-PR; λmax ≈ 490 nm) and green-absorbing PR (G-PR; λmax ≈ 525 nm). In this report, we present conversion of B-PR into G-PR using anomalous pH effect. B-PR in LC1-200, marine γ-proteobacteria, absorbs 497 and 513 nm maximally at pH 7 and 4, respectively, whose pH titration was reversible (pKa = 4.8). When pH was lowered from 4, the λmax was further red-shifted (528 nm at pH 2). This is unusual because blue shift occurs by chloride binding in the case of bacteriorhodopsin. Surprisingly, when pH was increased from 2 to 7, the λmax of this B-PR was further red-shifted to 540 nm, indicating that green-absorbing PR (PR540) is created only by changing pH. The present study reports the conformational flexibility of microbial rhodopsins, leading to the switch of absorbing color by a simple pH change.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
J Phys Chem Lett
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Japão