能源問題一直是現(xiàn)代社會(huì)的一個(gè)重要的問題,，不過美國(guó)羅徹斯特 (Rochester)大學(xué)的研究人員,，發(fā)表在最新一期美國(guó)國(guó)家科學(xué)院院刊 (PNAS)的一篇論文，揭露了該校的科學(xué)家,，找到了微生物用來生產(chǎn)乙醇 (Ethanol)的酵素基因,，將來很可能利用這種蛋白質(zhì)酵素的作用，分解原本像是除草或是稻桿這類的廢棄物,，轉(zhuǎn)換成干凈清潔的能源,。
據(jù)該校化學(xué)工程學(xué)系 David H. Wu教授表示,，這次研究人員以可以分解大量生物質(zhì)量 (biomass)的細(xì)菌為目標(biāo),，深入的分析細(xì)菌酵素的活動(dòng)，希望能夠找到加速產(chǎn)生乙醇的方法,，因?yàn)榫瓦^去的經(jīng)驗(yàn)來說,，細(xì)菌是可以透過分解代謝的方式，產(chǎn)生可以作為能源使用的乙醇,，但這個(gè)轉(zhuǎn)化的過程過于緩慢,，特別是屬于大質(zhì)量廢棄物的木質(zhì)材料，質(zhì)地非常的堅(jiān)硬,，不容易被酵素蛋白質(zhì)所分解,，其它像是玉米這類較軟的材質(zhì)，雖然可以較容易的轉(zhuǎn)換成為酒精,，但卻擁有較高的經(jīng)濟(jì)價(jià)值,，因此找出細(xì)菌到底用那一類酵素，透過怎樣的過程來有效率的產(chǎn)生酒精,，就成了研究人員首要的目標(biāo),。
研究人員把目標(biāo),，放在一種稱為 C. thermocellum的細(xì)菌身上，因?yàn)榫拖惹暗牧私?，該?xì)菌只利用一個(gè)步驟,，就可以產(chǎn)生酒精，不過該細(xì)菌身上有多達(dá) 100多種的酵素,，光憑排列組合,，很難找出真正的作用者，研究人員仔細(xì)的分析,，終于發(fā)現(xiàn)細(xì)菌會(huì)透過少量的特殊酵素，藉由產(chǎn)生一種稱為 laminaribiose的糖類,，來感應(yīng)周遭大量纖維素的出現(xiàn),，因而啟動(dòng)稱為 CelC和 LicA的木質(zhì)分解酵素。
研究人員找到了這兩個(gè)酵素蛋白質(zhì),，就等于開了一扇大門,，目前透過定序的過程，探究酒精代謝的關(guān)鍵,，也許在未來,，光憑腐蝕的樹干，就可以獲得推動(dòng)汽車的燃料,。
(資料來源 : Bio.com)
部分英文原文：
Published online before print February 27, 2007, 10.1073/pnas.0700087104
PNAS | March 6, 2007 | vol. 104 | no. 10 | 3747-3752
Induction of the celC operon of Clostridium thermocellum by laminaribiose
Michael Newcomb, Chun-Yu Chen, and J. H. David Wu*
Department of Chemical Engineering, University of Rochester, Rochester, NY 14627-0166
Communicated by Arnold L. Demain, Drew University, Madison, NJ, January 5, 2007 (received for review December 12, 2006)
Clostridium thermocellum is an anaerobic, thermophilic, cellulolytic, and ethanogenic bacterium. It produces an extracellular multiprotein complex termed the cellulosome, which consists of >70 subunits, most of them glycosyl hydrolases. It also produces many free glycosyl hydrolases. How the organism commands such a large number of genes and proteins for biomass degradation is an intriguing yet unresolved question. We identified glyR3, which is cotranscribed with the cellulase/hemicellulase genes celC and licA, as a potential cellulase transcription regulator. The gel-shift assay (EMSA) revealed that the recombinant GlyR3 bound specifically to the celC promoter region. GlyR3 was also identified from the lysate of the lichenan-grown cells, which bound to the same sequence. DNase I footprinting and competitive EMSA showed the binding site to be an 18-bp palindromic sequence with one mismatch. The DNA-binding activity was specifically inhibited by laminaribiose, a -1-3 linked glucose dimer, in a dose-dependent manner. In in vitro transcription analysis, celC expression was repressed by rGlyR3 in a dose-dependent manner. The repression was relieved by laminaribiose, also in a dose-dependent manner. These results indicate that GlyR3 is a negative regulator of the celC operon consisting of celC, glyR3, and licA, and inducible by laminaribiose. Thus, the bacterium may modulate the biosynthesis of its enzyme components to optimize its activity on an available biomass substrate, in this case, -1-3 glucan, because both CelC and LicA are active on the substrate. The results further indicate that, despite the insolubility of the biomass substrate, regulation of the degradative enzymes can be accomplished through soluble sugars generated by the action of the enzymes.
