Crystal structures of two tandem malectin-like receptor kinases involved in plant reproduction.

Complex cell-to-cell communication between the male pollen tube and the female reproductive organs is required for plant fertilization. A family of Catharanthus roseus receptor kinase 1-like (CrRLK1L) membrane receptors has been genetically implicated in this process. Here, crystal structures of the CrRLK1Ls ANXUR1 and ANXUR2 are reported at 1.48 and 1.1 Å resolution, respectively. The structures reveal a novel arrangement of two malectin-like domains connected by a short β-hairpin linker and stabilized by calcium ions. The canonical carbohydrate-interaction surfaces of related animal and bacterial carbohydrate-binding modules are not conserved in plant CrRLK1Ls. In line with this, the binding of chemically diverse oligosaccharides to ANXUR1 and HERCULES1 could not be detected. Instead, CrRLK1Ls have evolved a protein-protein interface between their malectin domains which forms a deep cleft lined by highly conserved aromatic and polar residues. Analysis of the glycosylation patterns of different CrRLK1Ls and their oligomeric states suggests that this cleft could resemble a binding site for a ligand required for receptor activation of CrRLK1Ls

Evolution of Moisture Distribution During Storage in a Composite Food Modelling and Simulation

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Effect of Temperature on Moisture Barrier Efficiency of Monoglyceride Edible Films in Cereal-Based Composite Foods

International audienceThe effects of temperature on moisture transfer within a composite food consisting of a sponge cake (SC) separated from a high moisture content agar gel (AG) by an acetylated monoglyceride (AMG1 and AMG2) film were investigated through moisture content profile experiments. A diffusion model was successfully used to predict moisture transfer within various composite foods (AG/SC, AG/AMG1/SC, and AG/AMG2/SC). The barrier efficiencies of the two hydrophobic films studied were reduced by temperature increase due to activation of diffusivity and equilibrium water sorption. Despite the low melting point of highly acetylated monoglyceride films, their barrier efficiency appeared to be less sensitive to temperature than monoglyceride films with a lower degree of acetylation. Consequently, in poor storage temperature conditions, these latter monoglyceride films seemed to be more effective in enhancing the shelf-life of the composite food studied here

Preventing Moisture Transfer in a Composite Food Using Edible Films: Experimental and Mathematical Study

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Modelling of Moisture Transfer in a Composite Food: Dynamic Water Properties in an Intermediate aw Porous Product in Contact with High aw Filling

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HSL1 and BAM1/2 impact epidermal cell development by sensing distinct signaling peptides.

The membrane receptor kinases HAESA and HSL2 recognize a family of IDA/IDL signaling peptides to control cell separation processes in different plant organs. The homologous HSL1 has been reported to regulate epidermal cell patterning by interacting with a different class of signaling peptides from the CLE family. Here we demonstrate that HSL1 binds IDA/IDL peptides with high, and CLE peptides with lower affinity, respectively. Ligand sensing capability and receptor activation of HSL1 require a SERK co-receptor kinase. Crystal structures with IDA/IDLs or with CLE9 reveal that HSL1-SERK1 complex recognizes the entire IDA/IDL signaling peptide, while only parts of CLE9 are bound to the receptor. In contrast, the receptor kinase BAM1 interacts with the entire CLE9 peptide with high affinity and specificity. Furthermore, the receptor tandem BAM1/BAM2 regulates epidermal cell division homeostasis. Consequently, HSL1-IDLs and BAM1/BAM2-CLEs independently regulate cell patterning in the leaf epidermal tissue