Longevity in vivo of primary cell wall cellulose synthases
Our work focuses on understanding the lifetime and thus stability of the three main cellulose synthase (CESA) proteins involved in primary cell wall synthesis of Arabidopsis. It had long been thought that a major means of CESA regulation was via their rapid degradation. However, our studies here have uncovered that AtCESA proteins are not rapidly degraded. Rather, they persist for an extended time in the plant cell.
Plant cellulose is synthesized by membrane-embedded cellulose synthase complexes (CSCs). The CSC is composed of cellulose synthases (CESAs), of which three distinct isozymes form the primary cell wall CSC and another set of three isozymes form the secondary cell wall CSC. We determined the stability over time of primary cell wall (PCW) CESAs in Arabidopsis thaliana seedlings, using immunoblotting after inhibiting protein synthesis with cycloheximide treatment. Our work reveals very slow turnover for the Arabidopsis PCW CESAs in vivo. Additionally, we show that the stability of all three CESAs within the PCW CSC is altered by mutations in individual CESAs, elevated temperature, and light conditions. Together, these results suggest that CESA proteins are very stable in vivo, but that their lifetimes can be modulated by intrinsic and environmental cues.
KeywordsArabidopsis thaliana Cellulose synthase Western blot Primary cell wall CESA Cycloheximide Protein lifetime
The authors thank Abhinaya Srikanth for the gift of Anti-UBIQUITIN antibody. This work was supported as part of The Center for Lignocellulose Structure and Formation, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0001090. The authors declare no conflict of interest.
CJ and WJB contributed equally as second and third authors. Conceived and designed the experiments: JLH WJB CTA MT. Performed the experiments: JLH WJB CJ. Analyzed the data: JLH WJB CTA MT. Wrote the paper: JLH WJB CTA MT.
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