title: Tubulin C-terminal Post-translational Modifications Do Not Occur in Wood Forming Tissue ofPopulus.
abstract: Cortical microtubules (MTs) are evolutionarily conserved cytoskeletal components with specialized roles in plants, including regulation of cell wall biogenesis. MT functions and dynamics are dictated by the composition of their monomeric subunits, α- (TUA) and β-tubulins (TUB), which in animals and protists are subject to both transcriptional regulation and post-translational modifications (PTM). While spatiotemporal regulation of tubulin gene expression has been reported in plants, whether and to what extent tubulin PTMs occur in these species remain poorly understood. We chose the woody perennialPopulusfor investigation of tubulin PTMs in this study, with a particular focus on developing xylem where high tubulin transcript levels support MT-dependent secondary cell wall deposition. Mass spectrometry and immunodetection concurred that detyrosination, non-tyrosination and glutamylation were essentially absent in tubulins isolated from wood-forming tissues ofP. deltoidesandP. tremula×alba. Label-free quantification of tubulin isotypes and RNA-Seq estimation of tubulin transcript abundance were largely consistent with transcriptional regulation. However, two TUB isotypes were detected at noticeably lower levels than expected based on RNA-Seq transcript abundance in bothPopulusspecies. These findings led us to conclude that MT composition during wood formation depends exclusively on transcriptional and, to a lesser extent, translational regulation of tubulin isotypes.
authors: Daniel B. Warnell School of Forestry and Natural Resources, University of GeorgiaAthens, GA, USA; Department of Genetics, University of GeorgiaAthens, GA, USA.
authors: Hao
authors: H
authors: Hu
authors: Institute of Bioinformatics, University of Georgia Athens, GA, USA.
authors: Xi
authors: X
authors: Gu
authors: Daniel B. Warnell School of Forestry and Natural Resources, University of GeorgiaAthens, GA, USA; Department of Genetics, University of GeorgiaAthens, GA, USA; Institute of Bioinformatics, University of GeorgiaAthens, GA, USA.
authors: Liang-Jiao
authors: LJ
authors: Xue
authors: Daniel B. Warnell School of Forestry and Natural Resources, University of Georgia Athens, GA, USA.
authors: Prashant S
authors: PS
authors: Swamy
authors: Daniel B. Warnell School of Forestry and Natural Resources, University of GeorgiaAthens, GA, USA; Department of Genetics, University of GeorgiaAthens, GA, USA.
authors: Scott A
authors: SA
authors: Harding
authors: Daniel B. Warnell School of Forestry and Natural Resources, University of GeorgiaAthens, GA, USA; Department of Genetics, University of GeorgiaAthens, GA, USA; Institute of Bioinformatics, University of GeorgiaAthens, GA, USA.
authors: Chung-Jui
authors: CJ
authors: Tsai
keywords: acetylation; detyrosination; glutamylation; microtubules; non-tyrosination; tension wood