Biogenesis of Cellulose Nanofibrils by a Biological Nanomachine

Abstract

Cellulose is synthesized by diverse organisms including prokaryotes, protists, animals, and plants. However, cellulose achieves its natural dominance within plants, where ß-1,4-linked glucan chains form long, semi-crystalline fibrils with nanoscale lateral dimensions. Although these fibrils have been conventionally called 'microfibrils', the term 'nanofibril' may be a more appropriate name in the age of nanoscience and nanotechnology (1). This term would reflect the fibril width (ranging between ∼1.5 and 25 nm in different cells) and the importance of surface properties in the chemistry and biological roles of cellulose. A main feature of nanomaterials (with 1-100 nm dimensions) is unique properties that: (a) often arise from a high surface-to-volume ratio; and (b) bridge between the molecular mechanics that applies to the molecular scale and the Newtonian physics that applies to larger objects (2, 3). The surface interactions of cellulose with other molecules are major determinants of its role as a scaffold for deposition of other wall components and the coherence and physical properties of the composite cell wall.In the plant cell wall, the cellulose nanofibrils are commonly 2-6 nm in diameter, with the larger nanofibrils usually occurring in secondary walls. All plant cells contain about ∼15% cellulose in the thin, extensible primary walls that surround growing cells. In this role, the cellulose nanofibrils are able to constrain the direction of plant cell expansion (as driven by isodiametric turgor pressure). This function derives from the high breaking strain energy (5 − 50 × 10 6 J/m 3 ) and tensile strength (∼GN/m 2 ) of cellulose fibrils, in the same range as high tensile steel. In proportion to its density, which is lower than steel,The Nanoscience and Technology of Renewable Biomaterials Edited

Phylogenetically Distinct Cellulose Synthase Genes Support Secondary Wall Thickening in Arabidopsis Shoot Trichomes and Cotton Fiber

“…Further work may reveal structural differences in cell walls that are deposited by proteins from the P1‐3 clades defined by AtCesA(1,3,6 or 6‐like proteins) vs. the S1‐3 clades defined by AtCesA(4,7,8) . This is a worthwhile goal for future research because uncovering potential common features of cellulose synthesized by different types of CesA proteins will aid the understanding of how particular cell wall properties are regulated at the nanoscale (Haigler and Roberts 2009). It is possible that cell wall types would be best defined by the clades of CesA proteins involved in their biosynthesis.…”

“…Although their precise role in the biochemical pathway of cellulose synthesis is still undefined, the cellulose synthases are UDP‐glucose: 1,4‐ß‐D‐glucosyltransferase enzymes in the glycosyltransferase family 2 (reviewed in Somerville 2006). In arabidopsis, members of a triplet of CesA isoforms (AtCesA1, 3, 6, or a 6‐like protein) have non‐redundant roles in primary wall cellulose synthesis (Persson et al 2007; Desprez et al 2007), whereas members of another triplet (AtCesA4, 7, 8) have non‐redundant roles in secondary wall cellulose synthesis in xylem cells (Taylor et al 2003) For convenience, the six clades that arabidopsis CesAs form with their orthologs from other seed plants have been designated P1, P2, and P3 (defined by AtCesA1, 3, and 6, respectively) and S1, S2, and S3 (defined by AtCesA 4, 7, and 8 , respectively) (Haigler and Roberts 2009). The remainder of the ten arabidopsis CesA genes appear to be relatively recently derived within P1 ( AtCesA10 ) and P3 ( AtCesA2, 5, and 9 ) in the crucifer lineage.…”

Application of rod-shaped cellulose nanocrystals in polyacrylamide hydrogels

“…Cellulose is usually biosynthesized by diverse organisms and deposited in a continuous elementary microfibrils, which can be about 5-10 nm in diameter and its length varies from 100 nm to several micrometers depending on the source of cellulose [1,2]. The elementary microfibrils were made up of amorphous and crystalline parts.…”

Cellulose Microfibril Formation by Surface-Tethered Cellulose Synthase Enzymes

“…It has previously been shown that the formation of cellulose by BcsA-B requires the presence of UDP-Glc, c-di-GMP, and a divalent cation such as Mg 2+ or Mn 2+ . − ,− However, the impact of BcsA-B surface immobilization on the nature and morphology of the synthesized cellulose has not been explored to date. Therefore, we immobilized polyhistidine-tagged BcsA-B on Ni surfaces at different surface densities and initiated cellulose biosynthesis upon addition of UDP-Glc, c-di-GMP, and Mg 2+ and imaged product formation by atomic force microscopy (AFM).…”