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عنوان فارسی مقاله:
خصوصیات فتوشیمیایی رودوپسین اکتین و وجود عملکردی آن در میزبان طبیعی
عنوان انگلیسی مقاله:
Photochemical characterization of actinorhodopsin and its functional existence in the natural host
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Microbial rhodopsins are ubiquitous membrane proteins in unicellular microorganisms [1,2]. They commonly consist of seven transmembrane helices surrounding a chromophore retinal, which binds to a conserved lysine residue in the last helix via a protonated Schiff base (PSB; the deprotonated Schiff base is abbreviated as SB). Upon illumination, the retinal undergoes isomerization from an all-trans to a 13-cis configuration. This change elevates the protein to the excited state, which is thermally relaxed to the original state via various photochemical intermediates. During this cyclic reaction, called the photocycle, microbial rhodopsin performs various roles, including light-driven ion pumps, ion channels, and photosensory transductions. In 1971, the first microbial rhodopsin was discovered in an extremely halophilic archaeon, Halobacterium salinarum, and named bacteriorhodopsin (BR) [3]. Subsequently, it was proven that BR acts as an outward H+ pump and can drive cellular ATP synthesis by creating an H+-electrochemical gradient across the cell membrane [4]. Later, three relatives with different functions were discovered from the same archaeon: inward Cl− pump halorhodopsin [5], phototaxis sensors sensory rhodopsin I [6], and sensory rhodopsin II (also called phoborhodopsin) [7]. For approximately 30 years, research on microbial rhodopsins was confined to these four archaeal rhodopsins [8]. Since 1999, however, the genes for other microbial rhodopsins have been identified in various microorganisms, including eubacteria, fungi, algae, and even viruses. Some new members have the same functions as the archaeal rhodopsins, whereas others perform novel roles, acting as outward Na+ pumps [9,10], cation and anion channels [11–14], and sensors for the regulation of gene expression [15]. Thus, microbial rhodopsins are now identified as a large and diverse family. H+ pumps define the largest functional class in the microbial rhodopsins and are widespread in various microorganisms inhabiting a broad range of environments. For aqueous environments, their abundances have been clarified through metagenomic analyses. For marine environments, the gene encoding the H+ pump was first identified in 2000 in a DNA fragment from an uncultivated γ-proteobacterium (the SAR86 group), which is one of the most abundant marine bacterioplankton [16]. This H+ pump was named proteorhodopsin (PR). The expression of photoactive PR was verified in native planktonic membrane preparations [17]. Later, PR genes were identified in other oceanic microbial groups, and it was established that PRencoding microorganisms are common in the world oceans (for reviews, see [8,18]). The cellular expression of PR and its H+-pumping activity were also proven in cultivated host strains. In some strains, lightactivated PR conferred observable benefits on the cells, such as growth enhancement, fuel CO2 fixation, and extended survival under starvation. Functional PR is available from the heterologous Escherichia coli system with exogenous retinal [16]. Thus, the photochemistry of PR has been examined in detail (for reviews, see refs [2,19,20]). For non-marine aqueous environments, metagenomic analysis revealed that a PR-related but phylogenetically distinct gene group is present in high abundance [21]. This predicted H+-pump group was named actinorhodopsin (ActR) because these genes are exclusively associated with actinobacteria, which are common inhabitants of freshwater environments [22]. Later, ActR genes were indeed found in cultivated freshwater actinobacteria [23] and further identified in other freshwater bacterioplankton [24]. Thus, it is now established that ActR genes are widespread in freshwater environments. In contrast to PR, ActR genes are almost completely absent in marine environments [21].
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کلمات کلیدی:
Photochemical characterization of actinorhodopsin and its functional ... https://meta.science/.../27659506_photochemical_characterization_of_actinorhodopsin_... Oct 26, 2016 - Makoto Demura | Actinorhodopsin (ActR) is a light-driven outward H(+) pump. Although the genes of ActRs are widely spread among ... Photochemical characterization of actinorhodopsin and its functional ... www.zoodyab.ir/.../128111-photochemical-characterization-of-acti... - Translate this page Sep 20, 2016 - Although the genes of ActRs are widely spread among freshwater bacterioplankton, there are no prior data on their functional expression in ... Photochemical characterization of actinorhodopsin and its functional ... test.pubpharm.de/vufind/Record/NLM261132741?institution... - Translate this page Sep 24, 2016 - Actinorhodopsin (ActR) is a light-driven outward H(+) pump. Although the genes of ActRs are widely spread among freshwater bacterioplankton ... Photochemical characterization of actinorhodopsin and its functional ... www.scilit.net/article/10.1016/j.bbabio.2016.09.006 Sep 20, 2016 - Photochemical characterization of actinorhodopsin and its functional existence in the natural host. Shintaro Nakamura, Takashi Kikukawa, Jun ... Photochemical characterization of actinorhodopsin and its functional ... jglobal.jst.go.jp/en/public/201602242226806909 Article“Photochemical characterization of actinorhodopsin and its functional existence in the natural host” Detailed information of the J-GLOBAL is a service ... Characterization of an Unconventional Rhodopsin from the ... jb.asm.org/content/197/16/2704.full by JL Keffer - 2015 - Cited by 7 - Related articles In addition, rhodopsins may differ in their maximum absorption peaks (480 to ... To date, no study has characterized the function of the actinorhodopsins, ...... Spectroscopic and photochemical characterization of a deep ocean proteorhodopsin. Neue Publikation am ILIM/New publication... - Research Institute for ... https://www.facebook.com/Mondseelimnology/posts/916170261848369 Photochemical characterization of actinorhodopsin and its functional existence in the natural host. Biochimica et Biophysica Acta-Bioenergetics 1857: ...
