細(xì)菌視紫紅質(zhì)的魔術(shù)內(nèi)幕
細(xì)菌視紫紅質(zhì)是存在于Halobacterium
salinarum中的一個(gè)膜上的蛋白質(zhì),它能夠僅僅依賴光的能量就將質(zhì)子泵出胞外。這項(xiàng)魔術(shù)的內(nèi)幕經(jīng)過(guò)30年的研究,終于將完全的展現(xiàn)在人們面前。我們現(xiàn)在可以從原子水平上看一看轉(zhuǎn)運(yùn)是怎樣進(jìn)行的了。
細(xì)菌視紫紅質(zhì)在泵出質(zhì)子的循環(huán)中會(huì)有五個(gè)不同的中間體,KCMNO。由于細(xì)菌視紫紅質(zhì)發(fā)光基團(tuán)視黃醛的顏色變化,這五種中間體很容易區(qū)分。為了進(jìn)一步研究,科學(xué)家希望得到細(xì)菌視紫紅質(zhì)的結(jié)晶結(jié)構(gòu)。因?yàn)槟さ鞍椎碾y結(jié)晶化及細(xì)菌視紫紅質(zhì)中間體的不穩(wěn)定,這些技術(shù)難題直到去年才得以解決,Nature報(bào)道的三個(gè)結(jié)構(gòu)已經(jīng)能將謎團(tuán)最后解開了。
細(xì)菌視紫紅質(zhì)包含了7個(gè)跨膜螺旋,環(huán)形排列形成質(zhì)子通道,視黃醛位于通道中央,與G螺旋216位賴氨酸通過(guò)質(zhì)子化希氏堿結(jié)合,當(dāng)視黃醛與光子發(fā)生碰撞后,它將從全反式轉(zhuǎn)變?yōu)?3順,然后引起周圍側(cè)鏈的構(gòu)象變化,由于新環(huán)境的不穩(wěn)定,希式堿的質(zhì)子移至C螺旋85位的天冬氨酸,接著C螺旋96位天冬氨酸將希式堿質(zhì)子化,這時(shí)質(zhì)子通道的胞質(zhì)入口擴(kuò)大,一個(gè)質(zhì)子進(jìn)入,將96位天冬氨酸質(zhì)子化,85位的質(zhì)子于是通過(guò)氫鍵和水送至胞外,最終,視黃醛恢復(fù)全反構(gòu)象,各螺旋回復(fù)起始位置,開始新的循環(huán)。
知其結(jié)構(gòu)知其功能,這句老話再一次得到驗(yàn)證,雖然不能將每一個(gè)感興趣的蛋白質(zhì)都這么研究一番,但細(xì)菌視紫紅質(zhì)的研究還是會(huì)讓我們了解關(guān)于同是7螺旋跨膜結(jié)構(gòu)的G蛋白偶聯(lián)受體的許多信息。
相關(guān)文章:Original research paper
Royant, A. et al. Helix deformation is coupled to
vectorial proton transport in the photocycle of bacteriorhodopsin.
Nature 406, 645–648 (2000).
Sass, H. J. et al. Structural alterations for proton
translocation in the M state of wild-type bacteriorhodopsin. Nature
406, 649–653 (2000)
Subramaniam S. & Henderson, R. Molecular mechanism
of vectorial proton translocation by bacteriorhodopsin. Nature 406,653–657 (2000).
Further reading
Henderson, R. et al. Model for the structure of bacteriorhodopsin based on high-resolution electron cryo-microscopy. J. Mol. Biol. 213, 899–929 (1990).
Vonck, J. Structure of the bacteriorhodopsin mutant
F219L N intermediate revealed by electron crystallography. EMBO J. 19,2152–2160 (2000).
Edman, K. et al. High-resolution X-ray structure of an
early intermediate in the bacteriorhodopsin photocycle. Nature 401,822–826 (1999).
Luecke, H., Schobert, B., Richter, H. T., Cartailler, J. P. & Lanyi, J. K. Structural changes in bacteriorhodopsin
during ion transport at 2 angstrom resolution. Science 286, 255–261 (1999).
News & Views
Kuhlbrandt, W. Bacteriorhodopsin — the movie. Nature
406, 569–570 (2000)., 百拇醫(yī)藥
salinarum中的一個(gè)膜上的蛋白質(zhì),它能夠僅僅依賴光的能量就將質(zhì)子泵出胞外。這項(xiàng)魔術(shù)的內(nèi)幕經(jīng)過(guò)30年的研究,終于將完全的展現(xiàn)在人們面前。我們現(xiàn)在可以從原子水平上看一看轉(zhuǎn)運(yùn)是怎樣進(jìn)行的了。
細(xì)菌視紫紅質(zhì)在泵出質(zhì)子的循環(huán)中會(huì)有五個(gè)不同的中間體,KCMNO。由于細(xì)菌視紫紅質(zhì)發(fā)光基團(tuán)視黃醛的顏色變化,這五種中間體很容易區(qū)分。為了進(jìn)一步研究,科學(xué)家希望得到細(xì)菌視紫紅質(zhì)的結(jié)晶結(jié)構(gòu)。因?yàn)槟さ鞍椎碾y結(jié)晶化及細(xì)菌視紫紅質(zhì)中間體的不穩(wěn)定,這些技術(shù)難題直到去年才得以解決,Nature報(bào)道的三個(gè)結(jié)構(gòu)已經(jīng)能將謎團(tuán)最后解開了。
細(xì)菌視紫紅質(zhì)包含了7個(gè)跨膜螺旋,環(huán)形排列形成質(zhì)子通道,視黃醛位于通道中央,與G螺旋216位賴氨酸通過(guò)質(zhì)子化希氏堿結(jié)合,當(dāng)視黃醛與光子發(fā)生碰撞后,它將從全反式轉(zhuǎn)變?yōu)?3順,然后引起周圍側(cè)鏈的構(gòu)象變化,由于新環(huán)境的不穩(wěn)定,希式堿的質(zhì)子移至C螺旋85位的天冬氨酸,接著C螺旋96位天冬氨酸將希式堿質(zhì)子化,這時(shí)質(zhì)子通道的胞質(zhì)入口擴(kuò)大,一個(gè)質(zhì)子進(jìn)入,將96位天冬氨酸質(zhì)子化,85位的質(zhì)子于是通過(guò)氫鍵和水送至胞外,最終,視黃醛恢復(fù)全反構(gòu)象,各螺旋回復(fù)起始位置,開始新的循環(huán)。
知其結(jié)構(gòu)知其功能,這句老話再一次得到驗(yàn)證,雖然不能將每一個(gè)感興趣的蛋白質(zhì)都這么研究一番,但細(xì)菌視紫紅質(zhì)的研究還是會(huì)讓我們了解關(guān)于同是7螺旋跨膜結(jié)構(gòu)的G蛋白偶聯(lián)受體的許多信息。
相關(guān)文章:Original research paper
Royant, A. et al. Helix deformation is coupled to
vectorial proton transport in the photocycle of bacteriorhodopsin.
Nature 406, 645–648 (2000).
Sass, H. J. et al. Structural alterations for proton
translocation in the M state of wild-type bacteriorhodopsin. Nature
406, 649–653 (2000)
Subramaniam S. & Henderson, R. Molecular mechanism
of vectorial proton translocation by bacteriorhodopsin. Nature 406,653–657 (2000).
Further reading
Henderson, R. et al. Model for the structure of bacteriorhodopsin based on high-resolution electron cryo-microscopy. J. Mol. Biol. 213, 899–929 (1990).
Vonck, J. Structure of the bacteriorhodopsin mutant
F219L N intermediate revealed by electron crystallography. EMBO J. 19,2152–2160 (2000).
Edman, K. et al. High-resolution X-ray structure of an
early intermediate in the bacteriorhodopsin photocycle. Nature 401,822–826 (1999).
Luecke, H., Schobert, B., Richter, H. T., Cartailler, J. P. & Lanyi, J. K. Structural changes in bacteriorhodopsin
during ion transport at 2 angstrom resolution. Science 286, 255–261 (1999).
News & Views
Kuhlbrandt, W. Bacteriorhodopsin — the movie. Nature
406, 569–570 (2000)., 百拇醫(yī)藥
百拇醫(yī)藥網(wǎng) http://www.www.srpcoatings.com/Html/Info/News/67/06701.htm