title: Exploring the Plant-Microbe Interface by Profiling the Surface-Associated Proteins of Barley Grains.
abstract: Cereal grains are colonized by a microbial community that actively interacts with the plant via secretion of various enzymes, hormones, and metabolites. Microorganisms decompose plant tissues by a collection of depolymerizing enzymes, including β-1,4-xylanases, that are in turn inhibited by plant xylanase inhibitors. To gain insight into the importance of the microbial consortia and their interaction with barley grains, we used a combined gel-based (2-DE coupled to MALDI-TOF-TOF MS) and gel-free (LC-MS/MS) proteomics approach complemented with enzyme activity assays to profile the surface-associated proteins and xylanolytic activities of two barley cultivars. The surface-associated proteome was dominated by plant proteins with roles in defense and stress-responses, while the relatively less abundant microbial (bacterial and fungal) proteins were involved in cell-wall and polysaccharide degradation and included xylanases. The surface-associated proteomes showed elevated xylanolytic activity and contained several xylanases. Integration of proteomics with enzyme assays is a powerful tool for analysis and characterization of the interaction between microbial consortia and plants in their natural environment.
authors.affiliation: Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark , Elektrovej, Building 375, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Abida
authors.initials: A
authors.lastname: Sultan
authors.affiliation: Agricultural and Environmental Proteomics, Department of Systems Biology, Technical University of Denmark , Søltofts Plads, Building 224, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Birgit
authors.initials: B
authors.lastname: Andersen
authors.affiliation: Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark , Elektrovej, Building 375, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Birte
authors.initials: B
authors.lastname: Svensson
authors.affiliation: Agricultural and Environmental Proteomics, Department of Systems Biology, Technical University of Denmark , Søltofts Plads, Building 224, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Christine
authors.initials: C
authors.lastname: Finnie
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis* / Q000378:metabolism; D002523:Edible Grain / Q000378:metabolism* / Q000382:microbiology; D015180:Electrophoresis, Gel, Two-Dimensional; D043364:Endo-1,4-beta Xylanases / Q000032:analysis* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000032:analysis / Q000378:metabolism; D005656:Fungal Proteins / Q000032:analysis* / Q000378:metabolism; D001467:Hordeum / Q000378:metabolism* / Q000382:microbiology; D055442:Metabolome; D059013:Microbial Consortia / Q000502:physiology; D064307:Microbiota / Q000502:physiology; D010940:Plant Proteins / Q000032:analysis* / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013499:Surface Properties
chemical_list: D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D010940:Plant Proteins; D043364:Endo-1,4-beta Xylanases
keywords: cereal proteins; environmental proteomics; mass spectrometry; metaproteome; microbial communities; proteome analysis; xylanase activity