| Conformational heterogeneity and propagation of structural changes in the LOV2/Jalpha domain from Avena sativa phototropin 1 as recorded by temperature-dependent FTIR spectroscopy. | |
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MedLine Citation:
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PMID: 19580761 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Phototropins control phototropism, chloroplast movement, stomatal opening, and leaf expansion in plants. Phototropin 1 (phot1) is composed of a kinase domain linked to two blue light-sensing domains, LOV2 and LOV1, which bind flavin mononucleotide. Disruption of the interaction between the LOV2 domain and a helical segment named Jalpha, joining LOV to the kinase domain, induces the subsequent kinase activity of phototropin 1 and further-downstream signal transduction. Here we study the effects of temperature and hydration on the light-triggered signal propagation in the phot1 LOV2 domain of Avena sativa (AsLOV2/Jalpha), using Fourier transform infrared spectroscopy to unravel part of the molecular mechanism of phototropin 1. We report that AsLOV2/Jalpha shows an intense signal in the amide I and II regions, arising mainly from beta-sheet changes and the unbinding of the Jalpha helix from the Per-ARNT-Sim core and its subsequent partial unfolding. Importantly, these structural changes only occur under conditions of full hydration and at temperatures above 280 K. We characterized a newly isolated low-hydration intermediate that shows a downshift of high-frequency amide I signals and that possibly corresponds to loop tightening, without large beta-sheet or Jalpha structural changes. In addition, we report a heterogeneity in AsLOV2/Jalpha involving two different C(4)=O conformer populations, coexisting in the dark state and characterized by C(4)=O carbonyl frequencies at 1712 cm(-1) and 1694 cm(-1) that are attributable to a single H-bond and two H-bonds at this site, respectively. Such conformers display slightly shifted absorption spectra and cause a splitting of the 475-nm band in the ultraviolet/visible spectra of LOV domains at low temperature. |
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Authors:
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Maxime T A Alexandre; Rienk van Grondelle; Klaas J Hellingwerf; John T M Kennis |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Biophysical journal Volume: 97 ISSN: 1542-0086 ISO Abbreviation: Biophys. J. Publication Date: 2009 Jul |
Date Detail:
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Created Date: 2009-07-07 Completed Date: 2009-10-13 Revised Date: 2010-09-27 |
Medline Journal Info:
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Nlm Unique ID: 0370626 Medline TA: Biophys J Country: United States |
Other Details:
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Languages: eng Pagination: 238-47 Citation Subset: IM |
Affiliation:
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Department of Biophysics, Faculty of Sciences, Vrije Universiteit, 1081HV Amsterdam, The Netherlands. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Avena sativa Cryptochromes Flavoproteins / chemistry* Hot Temperature Hydrogen Bonding Light Models, Chemical Models, Molecular Plant Proteins / chemistry* Protein Conformation Protein Folding Protein Structure, Secondary Protein Structure, Tertiary Spectroscopy, Fourier Transform Infrared Temperature Water / chemistry |
| Chemical | |
Reg. No./Substance:
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0/Cryptochromes; 0/Flavoproteins; 0/Plant Proteins; 7732-18-5/Water |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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