Architecture of a catalytically active homotrimeric plant cellulose synthase complex

Cellulose is an essential plant cell wall component and represents the most abundant biopolymer on Earth. Supramolecular plant cellulose synthase complexes organize multiple linear glucose polymers into microfibrils as load-bearing wall components. We determined the structure of a poplar cellulose synthase CesA homotrimer that suggests a molecular basis for cellulose microfibril formation. This complex, stabilized by cytosolic plant-conserved regions and helical exchange within the transmembrane segments, forms three channels occupied by nascent cellulose polymers. Secretion steers the polymers toward a common exit point, which could facilitate protofibril formation. CesA’s N-terminal domains assemble into a cytosolic stalk that interacts with a microtubule-tethering protein and may thus be involved in CesA localization. Our data suggest how cellulose synthase complexes assemble and provide the molecular basis for plant cell wall engineering.

Strong, tough, and repeatable adhesion of an alternating peptide comprising phenyl glycine as a repeating unit

An alternating peptide comprising phenyl glycine as a repeating unit skeleton shows strong, tough, and repeatable adhesion originating from its viscoelastic properties and microfibril formation.

Functional analysis of zebrafish microfibril-associated glycoprotein-1 (Magp1) in vivo reveals roles for microfibrils in vascular development and function

Mutations in fibrillin-1 (FBN1) result in Marfan syndrome, demonstrating a critical requirement for microfibrils in vessel structure and function. However, the identity and function of many microfibril-associated molecules essential for vascular development and function have yet to be characterized. In our morpholino-based screen for members of the secretome required for vascular development, we identified a key player in microfibril formation in zebrafish embryogenesis. Microfibril-associated glycoprotein-1 (MAGP1) is a conserved protein found in mammalian and zebrafish microfibrils. Expression of magp1 mRNA is detected in microfibril-producing cells. Analysis of a functional Magp1-mRFP fusion protein reveals localization along the midline and in the vasculature during embryogenesis. Underexpression and overexpression analyses demonstrate that specific Magp1 protein levels are critical for vascular development. Integrin function is compromised in magp1 morphant embryos, suggesting that reduced integrin–matrix interaction is the main mechanism for the vascular defects in magp1 morphants. We further show that Magp1 and fibrillin-1 interact in vivo. This study implicates MAGP1 as a key player in microfibril formation and integrity during development. The essential role for MAGP1 in vascular morphogenesis and function also supports a wide range of clinical applications, including therapeutic targets in vascular disease and cardiovascular tissue engineering.