Disease relevance of CESA2

• The genes that synthesize cellulose in higher plants differ greatly from the well-characterized genes found in Acetobacter and Agrobacterium sp. More correctly designated as 'cellulose synthase catalytic subunits', plant cellulose synthase (CesA) proteins are integral membrane proteins, approximately 1,000 amino acids in length [1].
• Cellulose in cyanobacteria. Origin of vascular plant cellulose synthase [2]?

High impact information on CESA2

• Recent, simultaneous, live-cell imaging of cellulose synthase and microtubules indicates that the microtubules exert a direct influence on the orientation of cellulose deposition [3].
• Chemical and ultrastructural analyses together with map-based cloning indicate that the RSW1 locus of Arabidopsis encodes the catalytic subunit of cellulose synthase [4].
• Because cellulose synthase catalytic subunits do not appear to be N glycosylated, the N-glycan requirement apparently resides in other component(s) of the cellulose synthase machinery [5].
• By contrast, actin microfilaments do not colocalize with the CesA proteins and are unlikely to play a direct role in their localization [6].
• As critical determinants of growth anisotropy in plants, cortical microtubules are thought to constrain the movement of cellulose synthase complexes and thus align newly deposited cellulose microfibrils [7].

Biological context of CESA2

• Genetic complexity of cellulose synthase a gene function in Arabidopsis embryogenesis [8].
• Expressed sequence tag clone 75G11, which exhibits sequence similarity to cellulose synthase, was found to be tightly linked to irx3, and genomic clones containing the gene corresponding to clone 75G11 complemented the irx3 mutation [9].
• Interestingly, PtrCesA2 shares only 64% identity with our earlier reported PtrCesA1 from aspen suggesting its structural distinctness from the only other known CesA member from the aspen genome [10].
• Because RSW1 was previously shown to encode a catalytic subunit of cellulose synthase, the similar morphology of knf and rsw1-2 embryos suggests that the radially swollen phenotype of knf mutants is largely due to their cellulose deficiency [5].
• Based on elegant molecular genetic analyses, distinct classes of cellulose synthase (CesA) genes have been associated with either primary or secondary cell wall development in Arabidopsis [11].

Anatomical context of CESA2

• The irregular xylem3 locus of Arabidopsis encodes a cellulose synthase required for secondary cell wall synthesis [9].
• Spinning disk confocal microscopy revealed that CESA complexes in the plasma membrane moved at constant rates in linear tracks that were aligned and were coincident with cortical microtubules [12].
• Inhibition of microtubule polymerization changed the fine-scale distribution and pattern of moving CESA complexes in the membrane, indicating a relatively direct mechanism for guidance of cellulose deposition by the cytoskeleton [12].

Associations of CESA2 with chemical compounds

• Modifications of cellulose synthase confer resistance to isoxaben and thiazolidinone herbicides in Arabidopsis Ixr1 mutants [13].
• Resistance against herbicide isoxaben and cellulose deficiency caused by distinct mutations in same cellulose synthase isoform CESA6 [14].
• Treatment of the glucan fraction with cellulase digests the glucan and also releases protein that has been characterized as GhCesA-1 and GhCesA-2--proteins that are believed to represent the catalytic subunit of cellulose synthase [15].
• We show that reduced levels of cellulose synthesis, caused by mutations in cellulose synthase genes and in genes affecting cell expansion, activate lignin synthesis and defense responses through jasmonate and ethylene and other signaling pathways [16].
• Although Zn(2+) binding occurs only when the protein is in the reduced form, biochemical analyses show that under oxidative conditions, the GhCesA1 zinc-finger domain and also the full-length protein dimerize via intermolecular disulfide bonds, indicating CesA dimerization can be regulated by redox state [17].

Other interactions of CESA2

• Thus, the IRX3 gene encodes a cellulose synthase component that is specifically required for the synthesis of cellulose in the secondary cell wall [9].
• IRX1 shows homology to a previously described cellulose synthase (IRX3) [18].
• Based on the mutant phenotype and the functional conservation between CSLD3 and the genuine cellulose synthase proteins, we hypothesized that the CSLD3 protein is essential for the synthesis of polymers for the fast-growing primary cell wall at the root hair tip [19].
• Knockout of the AtCESA2 Gene Affects Microtubule Orientation and Causes Abnormal Cell Expansion in Arabidopsis [20].
• The most abundant transcripts encoded sucrose synthases that were specifically expressed in wood-forming tissues along with cellulose synthase and homologs of KORRIGAN and ELP1 [21].

Analytical, diagnostic and therapeutic context of CESA2

• We report here the molecular cloning and characterization of a new full-length cellulose synthase (CesA) cDNA, PtrCesA2 from aspen (Populus tremuloides) trees [10].
• Genetic mapping, complementation analysis, and sequence analysis revealed that CEV1 is the cellulose synthase CeSA3 [22].
• To define the specific cell types expressing these CesA genes, we explored the natural distribution patterns of PtrCesA3 and PtrCesA4 transcripts in a variety of aspen organs, such as leaves, petiole, stem, and roots, using in situ hybridization with hypervariable region-specific antisense riboprobes [23].

References