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Auto-inhibitory effects of an IQ motif on protein structure and function

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Item Type:Article
Title:Auto-inhibitory effects of an IQ motif on protein structure and function
Creators Name:Petzhold, D. and Lossie, J. and Behlke, J. and Keller, S. and Haase, H. and Morano, I.
Abstract:The denuded IQ2 domain, i.e. myosin heavy chain not associated with regulatory light chains, exerts an inhibitory effect on myosin ATPase activity. In this study, we elaborated a structural explanation for this auto-inhibitory effect of IQ2 on myosin function. We employed analytical ultracentrifugation, circular dichroism, and surface plasmon resonance spectroscopy to investigate structural and functional properties of a myosin heavy chain (MYH) head-rod fragment aa664-915. MYH(664-915) was monomeric, adopted a closed shape, and bound essential myosin light chains (HIS-MLC-1) with low affinity to IQ1. Deletion of IQ2, however opened MYH(664-915). Four amino acids present in IQ2 could be identified to be responsible for this auto-inhibitory structural effect: alanine mutagenesis of I814, Q815, R819, and W827 stretched MYH(664-915) and increased 30fold the binding affinity of HIS-MLC-1 to IQ1. In this study we show, that denuded IQ2 favours a closed conformation of myosin with a low HIS-MLC-1 binding affinity. The collapsed structure of myosin with denuded IQ2 could explain the auto-inhibitory effects of IQ2 on enzymatic activity of myosin.
Keywords:IQ Motif, Myosin, Myosin Light Chains, Analytical Ultracentrifugation, Protein Structure, Protein–Protein-Interaction, Animals, Rats
Source:Biochemical and Biophysical Research Communications
Publisher:Academic Press
Page Range:939-943
Date:11 June 2010
Official Publication:https://doi.org/10.1016/j.bbrc.2010.05.027
PubMed:View item in PubMed

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