Interactions among three distinct CesA proteins essential for cellulose synthesis

Abstract

In a screen to identify novel cellulose deficient mutants, three lines were shown to be allelic and define a novel complementation group, irregular xylem5 (irx5). IRX5 was cloned and encodes a member of the CesA family of cellulose synthase catalytic subunits (AtCesA4). irx5 plants have an identical phenotype to previously described mutations in two other members of this gene family (IRX1 and IRX3). IRX5, IRX3, and IRX1 are coexpressed in exactly the same cells, and all three proteins interact in detergent solubilized extracts, suggesting that three members of this gene family are required for cellulose synthesis in secondary cell walls. The association of IRX1 and IRX3 was reduced to undetectable levels in the absence of IRX5. Consequently, these data suggest that IRX5, IRX3, and IRX1 are all essential components of the cellulose synthesizing complex and the presence of all three subunits is required for the correct assembly of this complex.

Structure, organization, and functions of cellulose synthase complexes in higher plants

“…At least three types of CESA isoforms, called α 1 , α 2 , and β, may be necessary for the spontaneous arrangement of CESAs in each CelS Ding and Himmel, 2006). Consistent with this hypothesis, different types of CesA isoforms have been found to be coexpressed in Arabidopsis thaliana: AtCesA4, AtCesA7, and AtCesA8 (Taylor et al, 2003); barley: HvCesA1, HvCesA2, and HvCesA6 (Burton et al, 2004); poplar: PtrCesA1, PtrCesA2, and PtrCesA3 Bhandari et al, 2006); and rice: OsCesA4, OsCesA7, and OsCesA9 (Tanaka et al, 2003). However, expression of several CesA isoforms in the same cell does not necessarily indicate that they interact and are part of the same CelS.…”

Patterning of plant cell wall deposition by cortical microtubules

“…Whereas libriform fibres have a uniformly deposited secondary cell wall, tracheary elements have patterned secondary cell wall thickenings. Besides structural support for the plant as a whole, these patterned secondary wall thickenings resist forces during transport, preventing collapse of the vessel as mentioned previously 6,[9][10][11][12] . Secondary cell wall thickenings in tracheary elements are deposited in different patterns, such as rings, spirals, reticulated or pitted patterns 1,13-15 ( Fig.…”

“…Mutants in these secondary CesAs result in dwarfed Arabidopsis plants, caused by collapsed vessel elements indicating the importance of the secondary cell wall thickenings [9][10][11][12] . Tracheary elements are characterized by typical patterned secondary cell wall thickenings.…”

“…Cellulose synthase complexes responsible for cellulose microfibril synthesis in Arabidopsis (Arabidopsis thaliana) is a protein complex of the cellulose synthases CesA4, -7 and -8 9 . Mutants in these secondary CesAs result in dwarfed Arabidopsis plants, caused by collapsed vessel elements indicating the importance of the secondary cell wall thickenings [9][10][11][12] .…”

Cultura de células em suspensão como ferramenta para estudos em parede celular secundária em gramí­neas C4

“…Os dados de expressão por RT-qPCR demonstraram que a expressão de determinados genes foi mais fortemente induzida ao longo da transdiferenciação, enquanto para outros, este aumento na expressão relativa foi modesto, porém estatisticamente significativo (Fig. 10) (Burton et al, 2004) que estaria implicado na síntese de parede celular primária, enquanto o homólogo de CesA12 estaria envolvido na síntese de parede celular secundária tanto em cevada (Burton et al, 2004) quanto em A. thaliana (Taylor et al, 2000;Taylor et al, 2003). Contudo, ambos os genes apresentaram expressão significativa no entrenó de cana-de-açúcar com ativa deposição de parede celular secundária, indicando que, nesta espécie, os dois genes poderiam participar dos mesmos processos (Casu et al, 2007).…”