Biosynthesis and cell-wall deposition of a pectin-xyloglucan complex in pea.
Golgi-enriched enzyme preparations prepared from etiolated pea epicotyls incorporated [U-(14)C]galactose from UDP-[U-(14)C]galactose into the 1,4-beta-galactan sidechains of a pectin-xyloglucan complex. This complex could bind to paper and was degraded both by pectin-degrading enzymes and by a xyloglucan-specific endoglucanase. Gel permeation chromatography was used to assess the molecular size of the complex and of enzymically-degraded, galactan-containing fragments of it. Etiolated pea stems were labelled with [U-(14)C]sucrose for 1 h, and the newly-synthesised cell wall polysaccharides were extracted with EDTA or NaOH and fractionated by ion-exchange chromatography. The NaOH-extracted, acidic radioactive polysaccharides obtained in this way were also degraded both by pectin-degrading enzymes and by xyloglucan-specific endoglucanase. Analysis of the radioactive sugar composition indicated that neutral sugars characteristic of both pectin and xyloglucan were present. Analysis of the total non-radioactive, neutral sugar composition of the NaOH-extracted, acidic cell-wall polysaccharides indicated that pectin-xyloglucan complexes were a general feature of the cell wall in this tissue.
Cumming
Carol M
CM
Institute of Biomedical and Life Sciences, Plant Science Group, Glasgow University, Bower Building, Glasgow, G12 8QQ, UK.
Rizkallah
Hind D
HD
McKendrick
Kimberley A
KA
Abdel-Massih
Roula M
RM
Baydoun
Elias A-H
EA
Brett
Christopher T
CT
D002473:Cell Wall / Q000378:metabolism*; D002480:Cellulase / Q000378:metabolism; D005696:Galactosidases / Q000378:metabolism; D005936:Glucans / Q000737:chemistry / Q000378:metabolism*; D018532:Pisum sativum / Q000166:cytology* / Q000378:metabolism*; D010368:Pectins / Q000737:chemistry / Q000378:metabolism*; D018547:Plant Stems / Q000166:cytology / Q000378:metabolism; D011096:Polygalacturonase / Q000378:metabolism; D013997:Time Factors; D014990:Xylans / Q000737:chemistry / Q000378:metabolism*
D005936:Glucans; D014990:Xylans; C029353:xyloglucan; D010368:Pectins; D005696:Galactosidases; D011096:Polygalacturonase; D002480:Cellulase