title: An update on post-translational modifications of hydroxyproline-rich glycoproteins: toward a model highlighting their contribution to plant cell wall architecture.
abstract: Plant cell walls are composite structures mainly composed of polysaccharides, also containing a large set of proteins involved in diverse functions such as growth, environmental sensing, signaling, and defense. Research on cell wall proteins (CWPs) is a challenging field since present knowledge of their role into the structure and function of cell walls is very incomplete. Among CWPs, hydroxyproline (Hyp)-rich O-glycoproteins (HRGPs) were classified into three categories: (i) moderately glycosylated extensins (EXTs) able to form covalent scaffolds; (ii) hyperglycosylated arabinogalactan proteins (AGPs); and (iii) Hyp/proline (Pro)-Rich proteins (H/PRPs) that may be non-, weakly- or highly-glycosylated. In this review, we provide a description of the main features of their post-translational modifications (PTMs), biosynthesis, structure, and function. We propose a new model integrating HRGPs and their partners in cell walls. Altogether, they could form a continuous glyco-network with non-cellulosic polysaccharides via covalent bonds or non-covalent interactions, thus strongly contributing to cell wall architecture.
authors.affiliation: Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, UPS, UMR 5546 Castanet-Tolosan, France ; CNRS, UMR 5546 Castanet-Tolosan, France.
authors.forename: May
authors.initials: M
authors.lastname: Hijazi
authors.affiliation: Facultad de Ciencias Exactas y Naturales, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-CONICET), Universidad de Buenos Aires Buenos Aires, Argentina.
authors.forename: Silvia M
authors.initials: SM
authors.lastname: Velasquez
authors.affiliation: Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, UPS, UMR 5546 Castanet-Tolosan, France ; CNRS, UMR 5546 Castanet-Tolosan, France.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Jamet
authors.affiliation: Facultad de Ciencias Exactas y Naturales, Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-CONICET), Universidad de Buenos Aires Buenos Aires, Argentina.
authors.forename: José M
authors.initials: JM
authors.lastname: Estevez
authors.affiliation: Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, UPS, UMR 5546 Castanet-Tolosan, France ; CNRS, UMR 5546 Castanet-Tolosan, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Albenne
keywords: O-glycosylation; arabinogalactan protein; extensin; hydroxyproline; proline-rich protein