Identification and isolation of a pectin methylesterase isoform that could be involved in flax cell wall stiffening.
Pectin methylesterases (PMEs) are ubiquitous enzymes present in the plant cell wall. They catalyse the demethylesterification of homogalacturonic acid units of pectins, which, in turn, can be associated with different physiological phenomena. In this study, different flax (Linum usitatissimum L.) PME isoforms were observed: neutral (pI 7.0 and 7.5, MW: 110 kDa), basic (pI 8.3 and 8.5, MW: 110 kDa) and very basic (pI>9.5, MW: 38 kDa). In an attempt to identify most of the expressed cell wall LuPME isoforms, polyclonal antibodies were raised against a conserved region of PME. These antibodies allowed the purification of the very basic PME isoform (pI 9.5, MW: 36 kDa) from flax cells, designated LuPME5. This isoform corresponds to the Lupme5 cDNA isolated, at the same time, from flax hypocotyls, by using the RACE-PCR technique. Semi-quantitative PCR experiments showed that the Lupme5 transcript was highly expressed in the hypocotyl zones where elongation is being achieved. Thus, this enzyme may be involved in cell wall stiffening.
Al-Qsous
Suha
S
Laboratoire Signaux et régulation chez les végétaux, CNRS UMR 6037, IFRMP 23, Université de Rouen, 76821 Mont-Saint-Aignan Cedex, France.
Carpentier
Emilie
E
Klein-Eude
Dominique
D
Burel
Carole
C
Mareck
Alain
A
Dauchel
Hélène
H
Gomord
Véronique
V
Balangé
Alain Pierre
AP
D000595:Amino Acid Sequence; D001483:Base Sequence; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry* / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D002478:Cells, Cultured; D019597:Flax / Q000201:enzymology* / Q000235:genetics; D015870:Gene Expression; D018546:Hypocotyl / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism; D007527:Isoenzymes / Q000737:chemistry; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
D007527:Isoenzymes; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase