Journal article
Arabidopsis thaliana β-Glucosidases BGLU45 and BGLU46 hydrolyse monolignol glucosides
Phytochemistry (Oxford), Vol.67(15), pp.1651-1660
2006
DOI: 10.1016/j.phytochem.2006.05.022
PMID: 16814332
Abstract
Biochemical and molecular evidence are provided to support the hypothesis that
Arabidopsis thaliana β-glucosidases BGLU45 (At1g61810) and BGLU46 (At1g61820) participate in a monolignol glucoside/β-glucosidase system in lignification.
In higher plants, β-glucosidases belonging to glycoside hydrolase (GH) Family 1 have been implicated in several fundamental processes including lignification. Phylogenetic analysis of
Arabidopsis thaliana GH Family 1 has revealed that At1g61810 (BGLU45), At1g61820 (BGLU46), and At4g21760 (BGLU47) cluster with
Pinus contorta coniferin β-glucosidase, leading to the hypothesis that their respective gene products may be involved in lignification by hydrolysing monolignol glucosides. To test this hypothesis, we cloned cDNAs encoding BGLU45 and BGLU46 and expressed them in
Pichia pastoris. The recombinant enzymes were purified to apparent homogeneity by ammonium sulfate fractionation and hydrophobic interaction chromatography. Among natural substrates tested, BGLU45 exhibited narrow specificity toward the monolignol glucosides syringin (
K
m, 5.1
mM), coniferin (
K
m, 7
mM), and
p-coumaryl glucoside, with relative hydrolytic rates of 100%, 87%, and 7%, respectively. BGLU46 exhibited broader substrate specificity, cleaving salicin (100%),
p-coumaryl glucoside (71%;
K
m, 2.2
mM), phenyl-β-
d-glucoside (62%), coniferin (8%), syringin (6%), and arbutin (6%). Both enzymes also hydrolysed
p- and
o-nitrophenyl-β-
d-glucosides. Using RT-PCR, we showed that
BGLU45 and
BGLU46 are expressed strongly in organs that are major sites of lignin deposition. In inflorescence stems, both genes display increasing levels of expression from apex to base, matching the known increase in lignification.
BGLU45, but not
BGLU46, is expressed in siliques, whereas only
BGLU46 is expressed in roots. Taken together with recently described monolignol glucosyltransferases [Lim et al., J. Biol. Chem. (2001) 276, 4344–4349], our enzymological and molecular data support the possibility of a monolignol glucoside/β-glucosidase system in
Arabidopsis lignification.
Details
- Title: Subtitle
- Arabidopsis thaliana β-Glucosidases BGLU45 and BGLU46 hydrolyse monolignol glucosides
- Creators
- Luis L Escamilla-TreviñoWei ChenMarcella L CardMing-Che ShihChi-Lien ChengJonathan E Poulton
- Resource Type
- Journal article
- Publication Details
- Phytochemistry (Oxford), Vol.67(15), pp.1651-1660
- Publisher
- Elsevier Ltd
- DOI
- 10.1016/j.phytochem.2006.05.022
- PMID
- 16814332
- ISSN
- 0031-9422
- eISSN
- 1873-3700
- Language
- English
- Date published
- 2006
- Academic Unit
- Biology
- Record Identifier
- 9984217417702771
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