title: Exo- and endoglucanases of maize coleoptile cell walls: their interaction and possible regulation.
abstract: Glucanase-mediated degradation of beta-(1,3)(1,4)-glucans has been attributed to auxin-induced cell wall loosening and thus tissue growth in cereal plants, but the regulatory mechanisms for the auxin-enhancement of glucanase activities in situ are not fully understood. Here, we report evidence for possible mechanisms which might account for auxin-induced changes in glucanase activities. A likely cause for acceleration of wall glucan degradation is the change in the ratio of exo- and endoglucanases. The combined enzymes synergistically promote beta-(1,3)(1,4)-glucan hydrolysis. In addition, these enzyme activities are enhanced by other enzymic and non-enzymic proteins and are also partially stimulated by divalent cations such as Ca(2+) and Mg(2+) at certain pH values. The acceleration of glucan degradation mediated by auxin may be mediated by changes and/or interactions of any of these factors in situ.
authors.affiliation: Department of Biology and Earth Sciences, Faculty of Science, Ehime University, Matsuyama, Ehime, Japan. inouhe@sci.ehime-u.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Inouhe
authors.forename: K
authors.initials: K
authors.lastname: Hayashi
authors.forename: B R
authors.initials: BR
authors.lastname: Thomas
authors.forename: D J
authors.initials: DJ
authors.lastname: Nevins
mesh_terms: D002412:Cations / Q000494:pharmacology; D002473:Cell Wall / Q000201:enzymology; D002480:Cellulase / Q000378:metabolism*; D043326:Glucan 1,3-beta-Glucosidase; D005936:Glucans / Q000378:metabolism*; D007210:Indoleacetic Acids; D007700:Kinetics; D018515:Plant Leaves; D003313:Zea mays / Q000201:enzymology* / Q000254:growth & development; D001617:beta-Glucosidase / Q000378:metabolism*
chemical_list: D002412:Cations; D005936:Glucans; D007210:Indoleacetic Acids; D001617:beta-Glucosidase; D002480:Cellulase; D043326:Glucan 1,3-beta-Glucosidase