title: Arabinogalactan proteins are required for apical cell extension in the moss Physcomitrella patens.
abstract: Cell biological, structural, and genetic approaches have demonstrated the presence of arabinogalactan proteins (AGPs) in the moss Physcomitrella patens and provided evidence for their function in cell expansion and specifically in the extension of apical tip-growing cells. Inhibitor studies indicated that apical cell expansion in P. patens is blocked by synthetic AGP binding beta-glucosyl Yariv reagent (betaGlcYR). The anti-(1-->5)-alpha-L-arabinan monoclonal antibody LM6 binds to some AGPs in P. patens, to all plasma membranes, and to the cell wall surface at the most apical region of growing protonemal filaments. Moreover, LM6 labeling of cell walls at the tips of apical cells of P. patens was abolished in the presence of betaGlcYR, suggesting that the localized movement of AGPs from the plasma membrane to the cell wall is a component of the mechanism of tip growth. Biochemical and bioinformatic analyses were used to identify seven P. patens ESTs encoding putative AGP core proteins from homology with Arabidopsis thaliana, Brassica napus, and Oryza sativa sequences and from peptide fragments isolated from betaGlcYR-precipitated AGPs. Gene knockout by homologous recombination of one of these genes, P. patens AGP1, encoding a classical AGP core protein, resulted in reduced cell lengths in protonemal filaments, indicating a role for AGP1 in apical cell expansion in P. patens.
authors.affiliation: Centre for Plant Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom.
authors.forename: Kieran J D
authors.initials: KJ
authors.lastname: Lee
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Sakata
authors.forename: Shaio-Lim
authors.initials: SL
authors.lastname: Mau
authors.forename: Filomena
authors.initials: F
authors.lastname: Pettolino
authors.forename: Antony
authors.initials: A
authors.lastname: Bacic
authors.forename: Ralph S
authors.initials: RS
authors.lastname: Quatrano
authors.forename: Celia D
authors.initials: CD
authors.lastname: Knight
authors.forename: J Paul
authors.initials: JP
authors.lastname: Knox
mesh_terms: D017360:Arabidopsis / Q000378:metabolism; D029688:Brassica napus / Q000235:genetics / Q000378:metabolism; D019068:Bryopsida / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology*; D049108:Cell Enlargement; D002473:Cell Wall / Q000378:metabolism; D019295:Computational Biology; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D018745:Genome, Plant / Q000235:genetics; D015698:Genomic Library; D008969:Molecular Sequence Data; D009088:Mucoproteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012275:Oryza / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D011995:Recombination, Genetic / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D018076:DNA, Complementary; D009088:Mucoproteins; D010940:Plant Proteins; C006619:arabinogalactan proteins