Molecular Characterization and Subcellular Localization of Arabidopsis Class VIII Myosin, ATM1

Abstract

Background: Molecular properties of class VIII myosin are not characterized. Results: Arabidopsis class VIII myosin, ATM1, has low enzymatic activity and high affinity for actin and is primarily localized at the cell cortex. Conclusion: Our data suggest that ATM1 functions as a tension sensor/generator. Significance: This is the first report of enzymatic and motile properties of class VIII myosin.

Class XI Myosins Move Specific Organelles in Pollen Tubes and are Required for Normal Fertility and Pollen Tube Growth in Arabidopsis

“…The localization of class VIII myosins, as determined by immunolocalization and the expression of fluorescently labeled full-length or tail constructs, has implicated these myosins in cell-to-cell communication, cell division, and endocytosis in angiosperms and moss (Reichelt et al, 1999;Van Damme et al, 2004;Avisar et al, 2008;Golomb et al, 2008;Sattarzadeh et al, 2008;Yuan et al, 2011;Haraguchi et al, 2014;Wu and Bezanilla, 2014). On the other hand, class XI myosin mutants have been studied extensively in Arabidopsis (Arabidopsis thaliana), which revealed roles for class XI myosins in cell expansion and organelle motility (Ojangu et al, 2007(Ojangu et al, , 2012Peremyslov et al, 2008Peremyslov et al, , 2010Prokhnevsky et al, 2008;Park and Nebenführ, 2013).…”

Update on Myosin Motors: Molecular Mechanisms and Physiological Functions

“…Specifically, slow motors are unlikely to contribute to fast organelle movements, as has been confirmed for Myo11G (Peremyslov et al, 2010). Interestingly, the slow motors Myo11G and Myo8C (ATM1) of Arabidopsis also have a high affinity for actin (Haraguchi et al, 2014(Haraguchi et al, , 2016. This property suggests that these motors may be more prone to holding onto filaments and generating (or responding to) tension in the actin network than to functioning as motors that move actively along filaments.…”

“…Combinations of myosin VIII mutants with mutants affected in the preprophase band-associated mechanism should help to identify possible overlapping functions. Given the localization of full-length Myo8C to actin filaments in interphase cells (Haraguchi et al, 2014), it also should be interesting to investigate possible changes in the actin cytoskeleton in the quadruple Myo8 mutant.…”

“…Evidence for the functional specialization of these subtypes is still limited. Myosin VIII motors are smaller in size than myosin XI and localize primarily to the cell surface, where they are thought to function in endocytosis and plasmodesmatal trafficking (Reichelt et al, 1999;Golomb et al, 2008;Sattarzadeh et al, 2008;Haraguchi et al, 2014). In angiosperms, myosin VIII has evolved into at least two subtypes, but the functional relevance of this separation has not been addressed so far.…”

Cytokinesis defect in BY-2 cells caused by ATP-competitive kinase inhibitors

“…7 Recently actomyosin driven phragmoplast guidance was suggested in moss. 8 In BY-2 cells, myosin proteins have been reported to co-localize to the phragmoplast [8][9][10][11] and further investigation of actomyosin complex in cytokinesis appears highly promising. Cytokinesis defect in BY-2 cells induced by 5-ITu was characterized by inhibition of the cell plate expansion and changes in AFs dynamics, which were no longer concentrated on the cell plate under 5-ITu treatment.…”