康乃爾大學(xué)(Cornell University)的研究人員發(fā)現(xiàn)新的植物酵素,，能更有效的將纖維素(cellulose)等制造生質(zhì)能源的植物原料降解,，將比以玉米為原料的生質(zhì)能源更具經(jīng)濟(jì)效益。此研究發(fā)表于4月20日的Journal of Biological Chemistry期刊,。
Jocelyn Rose教授說：「從富含纖維素的植物來制造乙醇的過程中，最關(guān)鍵的步驟就是如何有效地利用生物轉(zhuǎn)化的過程,，將含有大量纖維素的植物細(xì)胞壁降解為小分子的糖,。目前的技術(shù)是使用來自于微生物分泌的酵素cellulases，這個(gè)酵素具有一個(gè)結(jié)構(gòu)叫作cellulose-binding module (簡稱為CBM),，能有效的與纖維素結(jié)合,，然后將纖維素分解成木質(zhì)纖維素(lignocellulose)，包含本質(zhì)素(lignin)以及纖維素(cellulose),。而植物中雖然有類似cellulase的酵素,，但卻不具有CBM的結(jié)構(gòu),，因此,，無法有效的將纖維素分解，成為后段生質(zhì)乙醇制造的瓶頸,?！?/p>
Jocelyn Rose教授表示：「這個(gè)發(fā)現(xiàn)于蕃茄中的酵素Endo- -1,4-glucanase,，已證明能有效的分解植物細(xì)胞壁等物質(zhì),，有利于生質(zhì)乙醇的后段制造,。研究人員并推敲這個(gè)酵素可能是在生長快速的蕃茄中,，能有效分解較堅(jiān)硬的纖維素，由于能將較硬的組織分解,，才能使得蕃茄的果實(shí)較為松軟,。而這項(xiàng)發(fā)現(xiàn)也有助于生質(zhì)能源發(fā)展的進(jìn)行,?！?/p>
（編譯/陳瑞娟） (資料來源 : Bio.com)
原始出處:
J. Biol. Chem., Vol. 282, Issue 16, 12066-12074, April 20, 2007
A Tomato Endo--1,4-glucanase, SlCel9C1, Represents a Distinct Subclass with a New Family of Carbohydrate Binding Modules (CBM49)*
Breeanna R. Urbanowicz1, Carmen Catalá, Diana Irwin, David B. Wilson, Daniel R. Ripoll¶, and Jocelyn K. C. Rose2
From the Departments of Plant Biology and Molecular Biology and Genetics and the ¶Computational Biology Service Unit at the Cornell Theory Center, Cornell University, Ithaca, New York 14853
A critical structural feature of many microbial endo--1,4-glucanases (EGases, or cellulases) is a carbohydrate binding module (CBM), which is required for effective crystalline cellulose degradation. However, CBMs are absent from plant EGases that have been biochemically characterized to date, and accordingly, plant EGases are not generally thought to have the capacity to degrade crystalline cellulose. We report the biochemical characterization of a tomato EGase, Solanum lycopersicum Cel8 (SlCel9C1), with a distinct C-terminal noncatalytic module that represents a previously uncharacterized family of CBMs. In vitro binding studies demonstrated that this module indeed binds to crystalline cellulose and can similarly bind as part of a recombinant chimeric fusion protein containing an EGase catalytic domain from the bacterium Thermobifida fusca. Site-directed mutagenesis studies show that tryptophans 559 and 573 play a role in crystalline cellulose binding. The SlCel9C1 CBM, which represents a new CBM family (CBM49), is a defining feature of a new structural subclass (Class C) of plant EGases, with members present throughout the plant kingdom. In addition, the SlCel9C1 catalytic domain was shown to hydrolyze artificial cellulosic polymers, cellulose oligosaccharides, and a variety of plant cell wall polysaccharides.
Received for publication, August 18, 2006 , and in revised form, January 26, 2007.
* This work was supported in part by United States Department of Agriculture NRI Award 2002-35304-12680 (to J. K. C. R. and C. C.) and by grants from the United States National Science Foundation Plant Genome Program (DBI-0606595) and New York State Office of Science, Technology, and Academic Research (NYSTAR). This research was conducted in part with the resources of the Cornell Theory Center, which receives funding from Cornell University, New York State, Federal agencies, foundations, and corporate partners. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The on-line version of this article (available at http://www.jbc.org) contains supplemental Tables S1 and S2.
1 Supported by United States Department of Agriculture Initiative for Future Agricultural and Food Systems Multidisciplinary Graduate Education Traineeship Fellowship 2001-52014-11484.
2 To whom correspondence should be addressed: Dept. of Plant Biology, 228 Plant Science Bldg., Cornell University, Ithaca, NY 14853. Tel.: 607-255-4781; Fax: 607-255-5407; E-mail: [email protected] .
