Tubulin tyrosine nitration regulates microtubule organization in plant cells

Yaroslav B Blume,Oleh M Demchuk,Yuliya A Krasylenko,Alla I Yemets

doi:10.3389/fpls.2013.00530

Abstract

During last years, selective tyrosine nitration of plant proteins gains importance as well-recognized pathway of direct nitric oxide (NO) signal transduction. Plant microtubules are one of the intracellular signaling targets for NO, however, the molecular mechanisms of NO signal transduction with the involvement of cytoskeletal proteins remain to be elucidated. Since biochemical evidence of plant α-tubulin tyrosine nitration has been obtained recently, potential role of this posttranslational modification in regulation of microtubules organization in plant cell is estimated in current paper. It was shown that 3-nitrotyrosine (3-NO2-Tyr) induced partially reversible Arabidopsis primary root growth inhibition, alterations of root hairs morphology and organization of microtubules in root cells. It was also revealed that 3-NO2-Tyr intensively decorates such highly dynamic microtubular arrays as preprophase bands, mitotic spindles and phragmoplasts of Nicotiana tabacum Bright Yellow-2 (BY-2) cells under physiological conditions. Moreover, 3D models of the mitotic kinesin-8 complexes with the tail of detyrosinated, tyrosinated and tyrosine nitrated α-tubulin (on C-terminal Tyr 450 residue) from Arabidopsis were reconstructed in silico to investigate the potential influence of tubulin nitrotyrosination on the molecular dynamics of α-tubulin and kinesin-8 interaction. Generally, presented data suggest that plant α-tubulin tyrosine nitration can be considered as its common posttranslational modification, the direct mechanism of NO signal transduction with the participation of microtubules under physiological conditions and one of the hallmarks of the increased microtubule dynamics.

Highlights

Nitric oxide (NO) is a key player in redox signaling pathways in plant cell revealing concentration-dependent effects—from the mild regulation of morphogenesis to the triggering of the programmed cell death (PCD) events (Neill et al, 2008; Baudouin, 2011)
Fluctuations of NO levels provided by its exogenous donors (SNP, SNAP, GSNO, NO gas), scavenger (c-PTIO) and inhibitor of the mammalian NO-synthase (L-NAME, Nω-nitro-L-arginine methyl ester) affect A. thaliana primary root growth (Fernández-Marcos et al, 2011) and modulate MTs organization in root epidermal cells (Yemets et al, 2009, 2011)
The existing data about the interrelation of reactive nitrogen species (RNS) and MTs suggest that the organization of these cytoskeleton components could be regulated by both direct (Lindermayr et al, 2005; Landino et al, 2007; Yemets et al, 2011; Lozano-Juste et al, 2011) and indirect [e.g., modulation of cytosolic Ca2+ levels (Zhang et al, 2008)] mechanisms of NO signal transduction that are supposed to coexist in a plant cell dependent on local environment in the microcompartments (Zachgo et al, 2013), ROS/RNS balance (Livanos et al, 2012), cell/tissue/organ type (Yadav et al, 2013) and plant developmental stage (Begara-Morales et al, 2013)

Summary

INTRODUCTION

Nitric oxide (NO) is a key player in redox signaling pathways in plant cell revealing concentration-dependent effects—from the mild regulation of morphogenesis to the triggering of the programmed cell death (PCD) events (Neill et al, 2008; Baudouin, 2011). The enzymatic machinery of the mammalian α-tubulin detyrosination/tyrosination cycle includes tubulinspecific carboxypeptidase (TCP) that cleaves Tyr residues from the labile C-tail with the formation of Glu-tubulin and tubulinspecific tyrosine ligase (TTL) that adds non-modified or modified Tyr residues to the initial site (Westermann and Weber, 2003) This evolutionary conservative posttranslational modification regulates the dynamicity/stability of distinct MTs populations as dynamic tyrosinated and relatively stable detyrosinated populations of microtubules can coexist in cell (Westermann and Weber, 2003). In silico spatial reconstruction of kinesin-8 interaction with tyrosinated, detyrosinated and tyrosine nitrated C-terminus of Arabidopsis as one of the putative mechanisms of the regulation of MTs dynamics is provided

MATERIALS AND METHODS

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DISCUSSION