This Article Full Text Full Text (PDF) All Versions of this Article: 145/3/616    most recent pp.107.105049v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (15) Citing Articles via Google Scholar Google Scholar Articles by Le Roy, K. Articles by Van den Ende, W. Search for Related Content PubMed PubMed Citation Articles by Le Roy, K. Articles by Van den Ende, W. Agricola Articles by Le Roy, K. Articles by Van den Ende, W.

BIOCHEMICAL PROCESSES AND MACROMOLECULAR STRUCTURES

Unraveling the Difference between Invertases and Fructan Exohydrolases: A Single Amino Acid (Asp-239) Substitution Transforms Arabidopsis Cell Wall Invertase1 into a Fructan 1-Exohydrolase^1,[C]

Laboratory of Molecular Plant Physiology, Institute of Botany and Microbiology (K.L.R., W.L., B.D.C., A.V.L., W.V.d.E.) and Laboratory of Biocrystallography (W.L., M.V., A.R.), Katholieke Universiteit Leuven, B–3000 Leuven, Belgium

Plant cell wall invertases and fructan exohydrolases (FEHs) are very closely related enzymes at the molecular and structural level (family 32 of glycoside hydrolases), but they are functionally different and are believed to fulfill distinct roles in plants. Invertases preferentially hydrolyze the glucose (Glc)-fructose (Fru) linkage in sucrose (Suc), whereas plant FEHs have no invertase activity and only split terminal Fru-Fru linkages in fructans. Recently, the three-dimensional structures of Arabidopsis (Arabidopsis thaliana) cell wall Invertase1 (AtcwINV1) and chicory (Cichorium intybus) 1-FEH IIa were resolved. Until now, it remained unknown which amino acid residues determine whether Suc or fructan is used as a donor substrate in the hydrolysis reaction of the glycosidic bond. In this article, we present site-directed mutagenesis-based data on AtcwINV1 showing that the aspartate (Asp)-239 residue fulfills an important role in both binding and hydrolysis of Suc. Moreover, it was found that the presence of a hydrophobic zone at the rim of the active site is important for optimal and stable binding of Suc. Surprisingly, a D239A mutant acted as a 1-FEH, preferentially degrading 1-kestose, indicating that plant FEHs lacking invertase activity could have evolved from a cell wall invertase-type ancestor by a few mutational changes. In general, family 32 and 68 enzymes containing an Asp-239 functional homolog have Suc as a preferential substrate, whereas enzymes lacking this homolog use fructans as a donor substrate. The presence or absence of such an Asp-239 homolog is proposed as a reliable determinant to discriminate between real invertases and defective invertases/FEHs.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Wim Van den Ende (wim.vandenende{at}bio.kuleuven.be).

^[C] Some figures in this article are displayed in color online but in black and white in the print edition.

www.plantphysiol.org/cgi/doi/10.1104/pp.107.105049

^* Corresponding author; e-mail wim.vandenende{at}bio.kuleuven.be.

Received July 3, 2007; accepted September 7, 2007; published September 14, 2007.

This article has been cited by other articles:

				L. Vandesteene, M. Ramon, K. Le Roy, P. Van Dijck, and F. Rolland A Single Active Trehalose-6-P Synthase (TPS) and a Family of Putative Regulatory TPS-Like Proteins in Arabidopsis Mol Plant, January 28, 2010; (2010): ssp114v2 - ssp114. [Abstract] [Full Text] [PDF]

				L. Schroeven, W. Lammens, A. Kawakami, M. Yoshida, A. Van Laere, and W. Van den Ende Creating S-type characteristics in the F-type enzyme fructan:fructan 1-fructosyltransferase of Triticum aestivum L. J. Exp. Bot., September 1, 2009; 60(13): 3687 - 3696. [Abstract] [Full Text] [PDF]

				W. Lammens, K. Le Roy, L. Schroeven, A. Van Laere, A. Rabijns, and W. Van den Ende Structural insights into glycoside hydrolase family 32 and 68 enzymes: functional implications J. Exp. Bot., March 1, 2009; 60(3): 727 - 740. [Abstract] [Full Text] [PDF]

				B. Lasseur, L. Schroeven, W. Lammens, K. Le Roy, G. Spangenberg, H. Manduzio, R. Vergauwen, J. Lothier, M.-P. Prud'homme, and W. Van den Ende Transforming a Fructan:Fructan 6G-Fructosyltransferase from Perennial Ryegrass into a Sucrose:Sucrose 1-Fructosyltransferase Plant Physiology, January 1, 2009; 149(1): 327 - 339. [Abstract] [Full Text] [PDF]

				R. Valluru and W. Van den Ende Plant fructans in stress environments: emerging concepts and future prospects J. Exp. Bot., August 1, 2008; 59(11): 2905 - 2916. [Abstract] [Full Text] [PDF]

				A. F. Asega, J. R. O. do Nascimento, L. Schroeven, W. Van den Ende, and M. A. M. Carvalho Cloning, Characterization and Functional Analysis of a 1-FEH cDNA from Vernonia herbacea (Vell.) Rusby Plant Cell Physiol., August 1, 2008; 49(8): 1185 - 1195. [Abstract] [Full Text] [PDF]

				G.-P. Xue, C. L. McIntyre, C. L.D. Jenkins, D. Glassop, A. F. van Herwaarden, and R. Shorter Molecular Dissection of Variation in Carbohydrate Metabolism Related to Water-Soluble Carbohydrate Accumulation in Stems of Wheat Plant Physiology, February 1, 2008; 146(2): 441 - 454. [Abstract] [Full Text] [PDF]