Modifications in Chemical, Physical and Mechanical Properties of Nebbiolo (Vitis vinifera L.) Grape Berries Induced by Mixed Virus Infection

Modifications in grape quality parameters induced by mixed infection with GFLV and GFkV, GLRaV-1and GVA, and GLRaV-3 and GVA in three Nebbiolo clones were compared against healthy plants of thesame clones in two experimental vineyards in Piemonte, northwest Italy. The aim of the study was toevaluate the effect of virus infection on the mechanical properties of the berry skin and the whole berry asassessed by texture analysis tests, and on the amount and quality of berry skin phenols. Differences wereobserved in grapevine vigour, yield and juice composition, depending on the viral status of the plants. Theanthocyanin profile of the vines infected with GFV and GFkV and those infected with GLRaV-1 and GVAshowed a lower percentage of the more stable tri-substituted malvidin-3-glucoside and a higher percentageof cyanidin and peonidin-3-glucosides. Texture analysis showed that the viruses may increase berry-skinthickness and reduce phenol extractability. These effects carry practical implications for wine quality

Talin-mediated force transmission and talin rod domain unfolding independently regulate adhesion signaling

Talin protein is one of the key components in integrin-mediated adhesion complexes. Talins transmit mechanical forces between beta-integrin and actin, and regulate adhesion complex composition and signaling through the force-regulated unfolding of talin rod domain. Using modified talin proteins, we demonstrate that these functions contribute to different cellular processes and can be dissected. The transmission of mechanical forces regulates adhesion complex composition and phosphotyrosine signaling even in the absence of the mechanically regulated talin rod subdomains. However, the presence of the rod subdomains and their mechanical activation are required for the reinforcement of the adhesion complex, cell polarization and migration. Talin rod domain unfolding was also found to be essential for the generation of cellular signaling anisotropy, since both insufficient and excess activity of the rod domain severely inhibited cell polarization. Utilizing proteomics tools, we identified adhesome components that are recruited and activated either in a talin rod-dependent manner or independently of the rod subdomains. This study clarifies the division of roles between the force-regulated unfolding of a talin protein (talin 1) and its function as a physical linker between integrins and the cytoskeleton.Peer reviewe

The Distal Cytoplasmic Tail Of The Influenza A M2 Protein Dynamically Extends From The Membrane

The influenza A M2 protein is a multifunctional membrane-associated homotetramer that orchestrates several essential events in the viral infection cycle. The monomeric subunits of the M2 homotetramer consist of an N-terminal ectodomain, a transmembrane domain, and a C-terminal cytoplasmic domain. The transmembrane domain forms a four-helix proton channel that promotes uncoating of virions upon host cell entry. The membrane-proximal region of the C-terminal domain forms a surface-associated amphipathic helix necessary for viral budding. The structure of the remaining ~34 residues of the distal cytoplasmic tail has yet to be fully characterized despite the functional significance of this region for influenza infectivity. Here, we extend structural and dynamic studies of the poorly characterized M2 cytoplasmic tail. We used SDSL-EPR to collect site-specific information on the mobility, solvent accessibility, and conformational properties of residues 61–70 of the full-length, cell-expressed M2 protein reconstituted into liposomes. Our analysis is consistent with the predominant population of the C-terminal tail dynamically extending away from the membranes surface into the aqueous medium. These findings provide insight into the hypothesis that the C-terminal domain serves as a sensor that regulates how M2 protein participates in critical events in the viral infection cycle