Document Detail


Mutational and structural studies of the PixD BLUF output signal that affects light-regulated interactions with PixE.
MedLine Citation:
PMID:  21688827     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PixD (Slr1694) is a BLUF (blue-light-using FAD) photoreceptor used by the cyanobacterium Synechocystis sp. PCC6803 to control phototaxis toward blue light. In this study, we probe the involvement of a conserved Tyr8-Gln50-Met93 triad in promoting an output signal upon blue light excitation of the bound flavin. Analysis of acrylamide quenching of Trp91 fluorescence shows that the side chain of this residue remains partially solvent exposed in both the lit and dark states. Mutational analysis demonstrates that substitution mutations at Tyr8 and Gln50 result in the loss of the photocycle while a mutation of Met93 does not appreciably disturb the formation of the light-excited state and only minimally accelerates its decay from 5.7 to 4.5 s. However, mutations of Tyr8, Gln50, and Met93 disrupt the ability of PixD dimers to interact with PixE to form a higher-order PixD(10)-PixE(5) complex, which is indicative of a lit conformational state. Solution nuclear magnetic resonance spectroscopy and X-ray crystallographic analyses confirm that a Tyr8 to Phe mutation is locked in a pseudo-light-excited state revealing flexible areas in PixD that likely constitute part of an output signal upon light excitation of wild-type PixD.
Authors:
Hua Yuan; Vladimira Dragnea; Qiong Wu; Kevin H Gardner; Carl E Bauer
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2011-06-28
Journal Detail:
Title:  Biochemistry     Volume:  50     ISSN:  1520-4995     ISO Abbreviation:  Biochemistry     Publication Date:  2011 Jul 
Date Detail:
Created Date:  2011-07-19     Completed Date:  2011-09-19     Revised Date:  2011-09-26    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  United States    
Other Details:
Languages:  eng     Pagination:  6365-75     Citation Subset:  IM    
Copyright Information:
© 2011 American Chemical Society
Affiliation:
Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, USA.
Data Bank Information
Bank Name/Acc. No.:
PDB/3MZI
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MeSH Terms
Descriptor/Qualifier:
Acrylamide
Amino Acid Sequence
Bacterial Proteins / chemistry*,  genetics*,  metabolism
Chromatography, Gel
Crystallography, X-Ray
Darkness
Flavin-Adenine Dinucleotide / metabolism*
Fluorescence
Light*
Light Signal Transduction / radiation effects*
Magnetic Resonance Spectroscopy
Models, Molecular
Molecular Sequence Data
Mutant Proteins / chemistry
Mutation / genetics*
Peptides / chemistry
Photoreceptors, Microbial / chemistry*,  genetics,  metabolism
Protein Binding / radiation effects
Protein Structure, Tertiary
Sequence Alignment
Solvents
Spectrophotometry, Ultraviolet
Synechocystis / metabolism,  radiation effects
Tryptophan / metabolism
Grant Support
ID/Acronym/Agency:
GM40941/GM/NIGMS NIH HHS; R37 GM040941-24/GM/NIGMS NIH HHS
Chemical
Reg. No./Substance:
0/Bacterial Proteins; 0/Mutant Proteins; 0/Peptides; 0/Photoreceptors, Microbial; 0/Solvents; 146-14-5/Flavin-Adenine Dinucleotide; 73-22-3/Tryptophan; 79-06-1/Acrylamide

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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