Diverse roles of glycine residues conserved in photoactive yellow proteins
Yasushi Imamoto1, Sanae Tatsumi, Miki Harigai
1Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan. imamoto@vision-kyoto-u.jp
Abstract:
The role of glycine residues was studied by alanine-scanning mutagenesis using photoactive yellow protein, a structural prototype of PER ARNT SIM domain proteins, as a template. Mutation of glycine located close to the end of beta-strands with dihedral angles disallowed for alanine (Gly-37, Gly-59, Gly-86, and Gly-115) induces destabilization of the protein structure. On the other hand, substitution for Gly-77 and Gly-82, incorporated into the fifth alpha-helix, slows the photocycle by 15-20 times, suggesting that these residues regulate the light-induced structural switch between dark-state structure and signaling-state structure. Most importantly, a significant amount of G29A is in the bleached state and showed a 1000-fold slower photocycle. As O(epsilon2) of the carboxylic acid of Glu-46 is close enough for contact with C(alpha) of Gly-29, alanine mutation perturbs this packing. Fourier transform infrared spectroscopy demonstrated that the C=O(epsilon2) stretching mode of Glu-46 is 6 cm(-1) upshifted in G29A, suggesting that C(alpha) of Gly-29 acts as a proton donor for the C(alpha)-H...O(epsilon2) hydrogen bond with Glu-46, which stabilizes the dark-state structure. During the photocycle, Glu-46 becomes negatively charged by donating a proton to the chromophore, resulting in breakage of this hydrophobic packing and consequent conformational change of the protein.
More Related Videos
11:51Engineering 'Golden' Fluorescence by Selective Pressure Incorporation of Non-canonical Amino Acids and Protein Analysis by Mass Spectrometry and Fluorescence
Published on: April 27, 2018
16:16Genetically-encoded Molecular Probes to Study G Protein-coupled Receptors
Published on: September 13, 2013
Related Concept Videos
Activation and Inactivation of G Proteins
Conserved Binding Sites
Binding sites are often located in large pockets, and if their location on a protein’s surface is unknown, it can be predicted using various approaches. The energetic method computationally analyses the...
Amino acids
Protein Folding
Protein Folding
Protein Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
What are Proteins?
