4frz | pdb_00004frz

Arabidopsis KCBP motor domain dimerized via regulatory domain

spinqualitylabelsall models 4frz, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4frz is a 2 chain structure with sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ADP, EDO, IMD, MG Related: 3h4s Gene: KCBP, ZWI, At5g65930, K14B20.10 (Arabidopsis thaliana) Resources: FirstGlance, OCA, RCSB, PDBsum Function [KCBP_ARATH] Minus-end microtubule-dependent motor protein involved in the regulation of cell division and trichome morphogenesis. Possesses basal and microtubule-stimulated ATPase activities. Publication Abstract from PubMed Kinesin-like calmodulin binding protein (KCBP), a Kinesin-14 family motor protein, is involved in the structural organization of microtubules during mitosis and trichome morphogenesis in plants. The molecular mechanism of microtubule bundling by KCBP remains unknown. KCBP binding to microtubules is regulated by Ca2+-binding proteins that recognize its C-terminal regulatory domain. In this work, we have discovered a new function of the regulatory domain. We present a crystal structure of an Arabidopsis KCBP fragment showing that the C-terminal regulatory domain forms a dimerization interface for KCBP. This dimerization site is distinct from the dimerization interface within the N-terminal domain. Side chains of hydrophobic residues of the calmodulin binding helix of the regulatory domain form the C-terminal dimerization interface. Biochemical experiments show that another segment of the regulatory domain located beyond the dimerization interface, its negatively charged coil, is unexpectedly and absolutely required to stabilize the dimers. The strong microtubule bundling properties of KCBP are unaffected by deletion of the C-terminal regulatory domain. The slow minus-end directed motility of KCBP is also unchanged in vitro. Although the C-terminal domain is not essential for microtubule bundling, we suggest that KCBP may use its two independent dimerization interfaces to support different types of bundled microtubule structures in cells. Two distinct dimerization sites may provide a mechanism for microtubule rearrangement in response to Ca2+ signaling since Ca2+- binding proteins can disengage KCBP dimers dependent on its C-terminal dimerization interface. Plant Kinesin-Like Calmodulin Binding Protein Employs Its Regulatory Domain for Dimerization.,Vinogradova MV, Malanina GG, Waitzman JS, Rice SE, Fletterick RJ PLoS One. 2013 Jun 21;8(6):e66669. Print 2013. PMID:23805258 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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