1ugu
From Proteopedia
(New page: 200px<br /><applet load="1ugu" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ugu, resolution 1.20Å" /> '''Crystal structure of...) |
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| - | [[Image:1ugu.jpg|left|200px]]<br /><applet load="1ugu" size=" | + | [[Image:1ugu.jpg|left|200px]]<br /><applet load="1ugu" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1ugu, resolution 1.20Å" /> | caption="1ugu, resolution 1.20Å" /> | ||
'''Crystal structure of PYP E46Q mutant'''<br /> | '''Crystal structure of PYP E46Q mutant'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Photoactive yellow protein from Ectothiorhodospira halophila is a | + | Photoactive yellow protein from Ectothiorhodospira halophila is a photoreceptor protein involved in the negative phototaxis of this bacterium. Its chromophore (p-coumaric acid) is deprotonated in the ground state, which is stabilized by a hydrogen-bond network between Tyr42, Glu46 and Thr50. Glu46 is a key residue as it has been suggested that the proton at Glu46 is transferred to the chromophore during its photoconversion from the dark state to the signalling state. The structure of E46Q mutant protein was determined at 1.2 A resolution, revealing that the phenolic O atom of p-coumaric acid is hydrogen bonded to NH(2) of Gln46 in E46Q with a longer distance (2.86 +/- 0.02 A) than its distance (2.51 A) to Glu46 OH in the wild type. This and the decreased thermal stability of E46Q relative to the wild type show that this hydrogen bond is weakened in the E46Q mutant compared with the corresponding bond in the wild type. Several characteristic features of E46Q such as an alkali shift in the pK(a) and the rapid photocycle can be explained by this weakened hydrogen bond. Furthermore, the red shift in the absorption maximum in E46Q can be explained by the delocalization of the electron on the phenolic oxygen of p-coumaric acid owing to the weakening of this hydrogen bond. |
==About this Structure== | ==About this Structure== | ||
| - | 1UGU is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Halorhodospira_halophila Halorhodospira halophila] with HC4 as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1UGU is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Halorhodospira_halophila Halorhodospira halophila] with <scene name='pdbligand=HC4:'>HC4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1UGU OCA]. |
==Reference== | ==Reference== | ||
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[[Category: photorecepter]] | [[Category: photorecepter]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:24:32 2008'' |
Revision as of 13:24, 21 February 2008
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Crystal structure of PYP E46Q mutant
Overview
Photoactive yellow protein from Ectothiorhodospira halophila is a photoreceptor protein involved in the negative phototaxis of this bacterium. Its chromophore (p-coumaric acid) is deprotonated in the ground state, which is stabilized by a hydrogen-bond network between Tyr42, Glu46 and Thr50. Glu46 is a key residue as it has been suggested that the proton at Glu46 is transferred to the chromophore during its photoconversion from the dark state to the signalling state. The structure of E46Q mutant protein was determined at 1.2 A resolution, revealing that the phenolic O atom of p-coumaric acid is hydrogen bonded to NH(2) of Gln46 in E46Q with a longer distance (2.86 +/- 0.02 A) than its distance (2.51 A) to Glu46 OH in the wild type. This and the decreased thermal stability of E46Q relative to the wild type show that this hydrogen bond is weakened in the E46Q mutant compared with the corresponding bond in the wild type. Several characteristic features of E46Q such as an alkali shift in the pK(a) and the rapid photocycle can be explained by this weakened hydrogen bond. Furthermore, the red shift in the absorption maximum in E46Q can be explained by the delocalization of the electron on the phenolic oxygen of p-coumaric acid owing to the weakening of this hydrogen bond.
About this Structure
1UGU is a Single protein structure of sequence from Halorhodospira halophila with as ligand. Full crystallographic information is available from OCA.
Reference
Structure of photoactive yellow protein (PYP) E46Q mutant at 1.2 A resolution suggests how Glu46 controls the spectroscopic and kinetic characteristics of PYP., Sugishima M, Tanimoto N, Soda K, Hamada N, Tokunaga F, Fukuyama K, Acta Crystallogr D Biol Crystallogr. 2004 Dec;60(Pt 12 Pt 2):2305-9. Epub, 2004 Nov 26. PMID:15583378
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