Explore the vast range of titles available.

The Fasciclin 1 (FAS1) domain is an ancient structural motif in extracellular proteins present in all kingdoms of life and particularly abundant in plants. The FAS1 domain accommodates multiple interaction surfaces, enabling it to bind different ligands. The frequently observed tandem FAS1 arrangement might both positively and negatively regulate ligand binding. Additional protein domains and post-translational modifications are partially conserved between different evolutionary clades. Human FAS1 family members are associated with multiple aspects of health and disease. At the cellular level, mammalian FAS1 proteins are implicated in extracellular matrix structure, cell to extracellular matrix and cell to cell adhesion, paracrine signaling, intracellular trafficking and endocytosis. Mammalian FAS1 proteins bind to the integrin family of receptors and to protein and carbohydrate components of the extracellular matrix. FAS1 protein encoding plant genes exert effects on cellulosic and non-cellulosic cell wall structure and cellular signaling but to establish the modes of action for any plant FAS1 protein still requires biochemical experimentation. In fungi, eubacteria and archaea, the differential presence of FAS1 proteins in closely related organisms and isolated biochemical data suggest functions in pathogenicity and symbiosis. The inter-kingdom comparison of FAS1 proteins suggests that molecular mechanisms mediating interactions between cells and their environment may have evolved at the earliest known stages of evolution.

In a plant-specific mode of protein glycosylation, various sugars and glycans are attached to hydroxyproline giving rise to a variety of diverse glycoproteins. The sub-family of arabinogalactan proteins is implicated in a multitude of biological functions, however, the mechanistic role of glycosylation on AGPs by type II arabinogalactans is largely elusive. Some models suggest roles of the glycans such as in ligand-receptor interactions and as localized calcium ion store. Structurally different but possibly analogous types of protein glycosylation exist in animal and yeast models and roles for glycans were suggested in determining the fate of glycoproteins by affecting intracellular sorting or proteolytic activation and degradation. At present, only few examples exist that describe how the fate of artificial and endogenous arabinogalactan proteins is affected by glycosylation with type II arabinogalactans. In addition to other roles, these glycans might act as a molecular determinant for cellular localization and protein lifetime of many endogenous proteins.

Cell wall integrity control in plants involves multiple signaling modules that are mostly defined by genetic interactions. The putative co-receptors FEI1 and FEI2 and the extracellular glycoprotein FLA4 present the core components of a signaling pathway that acts in response to environmental conditions and insults to cell wall structure to modulate the balance of various growth regulators and, ultimately, to regulate the performance of the primary cell wall. Although the previously established genetic interactions are presently not matched by intermolecular binding studies, numerous receptor-like molecules that were identified in genome-wide interaction studies potentially contribute to the signaling machinery around the FLA4-FEI core. Apart from its function throughout the model plant Arabidopsis thaliana for the homeostasis of growth and stress responses, the FLA4-FEI pathway might support important agronomic traits in crop plants.

Background and AimsThe putative FASCICLIN-LIKE ARABINOGALACTAN PROTEIN 4 (At-FLA4) locus of Arabidopsis thaliana has previously been shown to be required for the normal growth of wild-type roots in response to moderately elevated salinity. However, the genetic and physiological pathway that connects At-FLA4 and normal root growth remains to be elucidated.MethodsThe radial swelling phenotype of At-fla4 was modulated with growth regulators and their inhibitors. The relationship of At-FLA4 to abscisic acid (ABA) signalling was analysed by probing marker gene expression and the observation of the At-fla4 phenotype in combination with ABA signalling mutants.Key ResultsApplication of ABA suppresses the non-redundant role of At-FLA4 in the salt response. At-FLA4 positively regulates the response to low ABA concentration in roots and is required for the normal expression of ABA- and abiotic stress-induced genes. The At-fla4 phenotype is enhanced in the At-abi4 background, while two genetic suppressors of ABA-induced gene expression are required for salt oversensitivity of At-fla4. Salt oversensitivity in At-fla4 is suppressed by the CYP707A inhibitor abscinazole E2B, and salt oversensitivity in At-fla4 roots is phenocopied by chemical inhibition of ABA biosynthesis.ConclusionsThe predicted lipid-anchored glycoprotein At-FLA4 positively regulates cell wall biosynthesis and root growth by modulating ABA signalling.

This article comments on: Zhao X, Liu N, Shang N, et al. 2018. Three UDP-xylose transporters (UXTs) participate in xylan biosynthesis by conveying cytosolic UDP-xylose into the Golgi lumen in Arabidopsis. Journal of Experimental Botany 69, 1125-1134..

Studying the biological roles of plant glycans enables a better understanding of plant growth and development under various environmental conditions in order to protect plants and exploit them for agriculture, forestry, or biotechnological products (De Coninck et al.,2021). Most O-glycans in plants, including microalgae (Mathieu-Rivet et al.) are attached to hydroxyproline (Hyp), an amino acid that is generated post-translationally by the action of prolyl-4-hydroxylases (P4H), as reported in two research articles in this Research Topic.Mócsai, Göritzer et al.take a long overdue new attempt at the substrate specificity of P4H isoforms, albeit with the result that four individual N. benthamiana P4H isoforms do not show differences in substrate selectivity in a non-plant expression system. [...]the mechanism of P4H selectivity remains an open question. [...]GALT8's biochemical function is consistent with the global growth phenotype of galt8 single mutants.

Background Understanding peoples’ evaluations of their health care is important to ensure appropriate health‐care services. Objectives To understand what factors influence peoples’ satisfaction with care and how interpersonal trust is established between doctors and cancer patients in Germany. Design A narrative interview study that included women with a diagnosis of breast cancer and men with a diagnosis of prostate cancer. A question‐focused analysis was conducted. Setting and participants Interviewees were sought across Germany through self‐help organizations, clinics, rehabilitation facilities, physicians and other health‐care professionals, in order to develop modules on experiencing cancer for the website krankheitserfahrungen.de (illness experiences.de). Results Satisfaction was related to the perception of having a knowledgeable and trusted physician. Trust was developed through particular interactions in which ‘medical expertise’ and ‘humaneness’ were enacted by physicians. Humaneness represents the ability of physicians to personalize medical expertise and thereby to convey working in the individual's best interest and to treat the patient as an individual and unique human being. This was fostered through contextual and relational factors including among others setting, time, information transfer, respect, availability, profoundness, sensitivity and understanding. Conclusion It was the ability to make oneself known to and know the patient in particular ways that allowed for satisfying care experiences by establishing interpersonal trust. This suggests the importance of conceptualizing the doctor‐patient relationship as a fundamentally reciprocal human interaction of caregiving and care‐receiving. At the core of the satisfying care experiences lies a doctor‐patient relationship with a profoundly humane quality.

Interactions between cell wall polymers are critical for establishing cell wall integrity and cell-cell adhesion. Here, we exploit the Arabidopsis (Arabidopsis thaliana) seed coat mucilage system to examine cell wall polymer interactions. On hydration, seeds release adherent mucilage layer strongly attached to the seed in addition to a nonadherent layer that can be removed by gentle agitation. Rhamnogalacturonan I (RG I) is the primary component of adherent mucilage, with homogalacturonan, cellulose, and xyloglucan constituting minor components. Adherent mucilage contains rays composed of cellulose and pectin that extend above the center of each epidermal cell. CELLULOSE SYNTHASE5 (CESA5) and the arabinogalactan protein SALT-OVERLY SENSITIVE5 (SOS5) required for mucilage adherence through unknown mechanisms. SOS5 has been suggested to mediate adherence by influencing cellulose biosynthesis. We, therefore, investigated the relationship between SOS5 and CESA5. cesa5-1 seeds show reduced cellulose, RG I, and ray size in adherent mucilage. In contrast, sos5-2 seeds have wild-type levels of cellulose but completely lack adherent RG and rays. Thus, relative to each other, cesa5-1 has a greater effect on cellulose, whereas sos5-2 mainly affects pectin. The double mutant cesa5-1 sos5-2 has a much more severe loss of mucilage adherence, suggesting that SOS5 and CESA5 function independently. Doublemutant analyses with mutations in MUCILAGE M0DIFIED2 and FLYING SAUCER1 that reduce mucilage release through pectin modification suggest that only SOS5 influences pectin-mediated adherence. Together, these findings suggest that SOS5 mediates adherence through pectins and does so independently of but in concert with cellulose synthesized by CESA5.