Peter Albersheim

Bio: Peter Albersheim is an academic researcher from University of Georgia. The author has contributed to research in topics: Cell wall & Xyloglucan. The author has an hindex of 93, co-authored 269 publications receiving 30805 citations. Previous affiliations of Peter Albersheim include Sapienza University of Rome & Institut national de la recherche agronomique.

Isolation and characterization of plant cell walls and cell wall components

Abstract: Publisher Summary This chapter describes the methods used for isolating and characterizing the noncellulosic polysaccharides of the primary walls of suspension-cultured sycamore cells These procedures are applicable to the study of other types of cell walls Cell walls form the basic structural framework of the plant, defining the shape and size of plant cells and tissues Cell walls are classified as either primary or secondary, depending upon their mechanical properties and chemical composition The primary cell wall is a mechanically dynamic structure encasing the cell during the period of rapid expansion that follows cell division The secondary cell wall is, relative to the primary cell wall, a mechanically static structure that determines the shape and size of the mature cell The chapter presents the experiments for the isolation of plant cell walls and the isolation of polysaccharides from cell walls and from extracellular polysaccharides of suspension-cultured plant cells and the chemical methods used for characterizing polysaccharides

Structure and function of the primary cell walls of plants.

Abstract: 1 Abbreviations and conventions used: AceA, aceric acid (3-C-carboxy-5-deoxy-L-xylose); Api, apiose; Ara, arabinose; Fuc, fucose; Gal, galactose; GalVA, galacturonic acid; Glc, glucose; GlcA, glucuronic acid; Rha, rhamnose; Xyl, xylose; PGA lyase, endo-IX-I,4polygalacturonic acid lyase; and PIIF, Proteinase Inhibitor Inducing Factor. All glycosyl residues are in the pyranoid ring form unless the furanoid form is indicated, e.g. Ara! Standard D and L notations are used when the absolute configuration of a particular glycosyl residue has been experimentally determined. When the absolute configuration has not been experiment­ ally determined, we omit the D or L notation, although in all cases studied the glycosyl residues Gal, Glc, Xyl, GalA, and GlcA have been found in the D configuration, and the glycosyl residues Fuc, Ara, and Rha in the L configuration. We use in this review a simplified linkage notation. All glycosyl residues (except the residue at the reducing end of an oligosaccharide, which is called a glycose residue) are glycosidically linked at C-l. This fact is assumed in the notation used, and, thus, C-\ is not mentioned. For example, a glycosyl residue designated as "terminal" (T) is glycosidically linked to another glycosyl or glycose residue only through C-J and contains no glycosyl residues linked to it. A glycosyl residue designated as 2-linked is glycosidicaUy linked to another glycosyl or glycose residue through C-J and has another glycosyl residue linked to it at 0-2. A glycosyl residue designated as 3,6-linked is glycosidically linked to another sugar through C-l and has glycosyl residues linked to it at 0-3 and 0-6; therefore, such a residue represents a branch point in a complex carbohydrate. The linkage from C l is also assumed in the notation for oligosac­ charides. Thus, L-Fuc � 2-D-Gal is a disaccharide in which an L-fucosyl residue is attached by an ()(-glycosidic bond from its C-l to 0-2 of a D-galactose residue. 2 Present address: Department of Bot

PHYTOALEXINS AND THEIR ELICITORS-A Defense Against Microbial Infection in Plants

Abstract: Some of the more important evidence is presented which supports the view that accumulation of phytoalexins at the site of attempted infection in plants. The accumulation of phytoalexins represents only one of a number of disease-resistance mechanisms in plants. Experiments are described demonstrating that the enzymes that catalyze the synthesis of phytoalexins are themselves synthesized de novo when plant cells are exposed to microbes of other effective stimuli. Evidence is also presented showing that phytoalexins, once accumulated, are catabolized or detoxified by many microorganisms as well as by the plants themselves. Elicitors are the major concern of this review. The literature is summarized in which elicitors are shown to be not only constituents of some microbes but also to be present in the cell walls of plants. A hypothesis is presented that suggests that all of the abiotic and some of the biotic elicitors stimulate phytoalexin accumulation by causing the release of an endogenous elicitor from the cell walls of plants. 108 references, 9 figures.

RHAMNOGALACTURONAN II: Structure and Function of a Borate Cross-Linked Cell Wall Pectic Polysaccharide

Abstract: ▪ Abstract Rhamnogalacturonan II (RG-II) is a structurally complex pectic polysaccharide that was first identified in 1978 as a quantitatively minor component of suspension-cultured sycamore cell walls. Subsequent studies have shown that RG-II is present in the primary walls of angiosperms, gymnosperms, lycophytes, and pteridophytes and that its glycosyl sequence is conserved in all vascular plants examined to date. This is remarkable because RG-II is composed of at least 12 different glycosyl residues linked together by more than 20 different glycosidic linkages. However, only a few of the genes and proteins required for RG-II biosynthesis have been identified. The demonstration that RG-II exists in primary walls as a dimer that is covalently cross-linked by a borate diester was a major advance in our understanding of the structure and function of this pectic polysaccharide. Dimer formation results in the cross-linking of the two homogalacturonan chains upon which the RG-II molecules are constructed and ...

The KEGG resource for deciphering the genome

Abstract: A grand challenge in the post-genomic era is a complete computer representation of the cell and the organism, which will enable computational prediction of higher-level complexity of cellular processes and organism behavior from genomic information. Toward this end we have been developing a knowledge-based approach for network prediction, which is to predict, given a complete set of genes in the genome, the protein interaction networks that are responsible for various cellular processes. KEGG at http://www.genome.ad.jp/kegg/ is the reference knowledge base that integrates current knowledge on molecular interaction networks such as pathways and complexes (PATHWAY database), information about genes and proteins generated by genome projects (GENES/SSDB/KO databases) and information about biochemical compounds and reactions (COMPOUND/GLYCAN/REACTION databases). These three types of database actually represent three graph objects, called the protein network, the gene universe and the chemical universe. New efforts are being made to abstract knowledge, both computationally and manually, about ortholog clusters in the KO (KEGG Orthology) database, and to collect and analyze carbohydrate structures in the GLYCAN database.

Structural models of primary cell walls in flowering plants: consistency of molecular structure with the physical properties of the walls during growth

Abstract: Advances in determination of polymer structure and in preservation of structure for electron microscopy provide the best view to date of how polysaccharides and structural proteins are organized into plant cell walls. The walls that form and partition dividing cells are modified chemically and structurally from the walls expanding to provide a cell with its functional form. In grasses, the chemical structure of the wall differs from that of all other flowering plant species that have been examined. Nevertheless, both types of wall must conform to the same physical laws. Cell expansion occurs via strictly regulated reorientation of each of the wall's components that first permits the wall to stretch in specific directions and then lock into final shape. This review integrates information on the chemical structure of individual polymers with data obtained from new techniques used to probe the arrangement of the polymers within the walls of individual cells. We provide structural models of two distinct types of walls in flowering plants consistent with the physical properties of the wall and its components.

Growth of the plant cell wall

Abstract: Plant cells encase themselves within a complex polysaccharide wall, which constitutes the raw material that is used to manufacture textiles, paper, lumber, films, thickeners and other products. The plant cell wall is also the primary source of cellulose, the most abundant and useful biopolymer on the Earth. The cell wall not only strengthens the plant body, but also has key roles in plant growth, cell differentiation, intercellular communication, water movement and defence. Recent discoveries have uncovered how plant cells synthesize wall polysaccharides, assemble them into a strong fibrous network and regulate wall expansion during cell growth.

A Renaissance of Elicitors: Perception of Microbe-Associated Molecular Patterns and Danger Signals by Pattern-Recognition Receptors

Abstract: Microbe-associated molecular patterns (MAMPs) are molecular signatures typical of whole classes of microbes, and their recognition plays a key role in innate immunity. Endogenous elicitors are similarly recognized as damage-associated molecular patterns (DAMPs). This review focuses on the diversity of MAMPs/DAMPs and on progress to identify the corresponding pattern recognition receptors (PRRs) in plants. The two best-characterized MAMP/PRR pairs, flagellin/FLS2 and EF-Tu/EFR, are discussed in detail and put into a phylogenetic perspective. Both FLS2 and EFR are leucine-rich repeat receptor kinases (LRR-RKs). Upon treatment with flagellin, FLS2 forms a heteromeric complex with BAK1, an LRR-RK that also acts as coreceptor for the brassinolide receptor BRI1. The importance of MAMP/PRR signaling for plant immunity is highlighted by the finding that plant pathogens use effectors to inhibit PRR complexes or downstream signaling events. Current evidence indicates that MAMPs, DAMPs, and effectors are all perceived as danger signals and induce a stereotypic defense response.