| Abstract Detail
Cytoskeleton Structure and Dynamics Li, Jian-Feng [1], Nebenführ, Andreas [2]. Organelle binding of myosin XI depends on two interacting globular tail subdomains. Myosin XI are actin-based molecular motors that are thought to drive organelle movements in plants, analogous to myosin V in animals and fungi. Similar domain organization of these myosins suggests that binding to organelles may occur via the globular tail domain in both types of motor, even though sequence similarity is low. To address this hypothesis, we developed a structure homology model for the globular tail of MYA1, a myosin XI isoform from Arabidopsis, based on the known structure of myosin V (Myo2p) globular tail. This model suggested an interaction between two subdomains of the globular tail which was verified by yeast two-hybrid assays and by an in vivo bimolecular fluorescence complementation (BiFC). Interface mapping demonstrated that this subdomain interaction depends critically on the C-terminus of helix H6 as well as three specific residues in helices H3 and H15, consistent with the structure prediction. The reconstituted globular tails of several Arabidopsis myosin XIs in BiFC assays targeted to peroxisomes in plant cells, identifying this domain as sufficient for cargo binding. Unlike myosin V, either tail subdomain of myosin XI alone was targeting-competent and responsible for association with different organelles. In addition, our data suggest the organelle binding is regulated by an allosteric interaction between two tail subdomains which is switched by the loop region between them. We conclude that the globular tail of myosin XI shares similar structure with that of myosin V, but has evolved plant-specific mechanisms in organelle binding.
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1 - The University of Tennessee, Department of Biochemistry, Cellular and Molecular Biology, Walters Life Sciences, M407, 1414 Cumberland Avenue, Knoxville, Tennessee, 37996, USA
2 - The University of Tennessee, Department of Biochemistry, Cellular and Molecular Biology
Keywords:
organelle targeting
myosin XI
structure homology model
tail subdomain
reconstituted tail.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P23007
Abstract ID:1155 |
