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首页> 外文期刊>Biochemistry >Bifurcation in the Ultrafast Dynamics of the Photoactive Yellow Proteins from Leptospira biflexa and Halorhodospira halophila
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Bifurcation in the Ultrafast Dynamics of the Photoactive Yellow Proteins from Leptospira biflexa and Halorhodospira halophila

机译：分枝杆菌钩端螺旋体和嗜盐嗜盐菌的光敏黄色蛋白的超快速动力学中。

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摘要

We explored the photoisomerization mechanisms in novel homologues of photoactive yellow protein (PYP) from Leptospira biflexa (Lbif) to identify conserved features and functional diversity in the primary photochemistry of this family of photoreceptors. In close agreement with the prototypical PYP from Halorhodospira halophila (Hhal), we observe excited-state absorbance near 375 nm and stimulated emission near 500 nm, with triphasic excited-state decay. While the excited-state decay for Lbif PYP is the slowest among those of known PYPs due to the redistribution of the amplitudes of the three decay components, the quantum yield for productive photocycle entry is very similar to that of Hhal PYP. Pro68 is highly conserved in PYPs and is important for the high photochemical quantum yield in Hhal PIT, but this residue is Ile in wild-type Lbif PIT. The level of photoproduct formation is slightly increased in I68P Lbif PYP, indicating that this residue regulates the photochemical quantum yield in the entire PIT family. Lbif PYP also exhibited a blue-shifted photoproduct previously undiscovered in ultrafast studies of PYP, which we have named pUV. We posit that pUV is a detour in the PIT photocycle with a twisted protonated pCAH configuration. Cryokinetic experiments with Hhal PIT confirmed the presence of pUV, but the population of this state in room-temperature ultrafast experiments is very small. These results resolve the long-standing inconsistency in the literature regarding the existence of a bifurcation in the room-temperature photocycle of PYP.
机译：我们探索了双侧钩端螺旋体（Lbif）的光敏黄色蛋白（PYP）的新同源物中的光异构化机制，以鉴定该家族感光细胞的主要光化学中的保守特征和功能多样性。与卤代嗜盐菌（Hallohodospira halophila，Hhal）的原型PYP紧密一致，我们观察到375 nm附近的激发态吸收和500 nm附近的激发发射，并出现三重激发态衰减。尽管由于三个衰变分量幅度的重新分布，Lbif PYP的激发态衰减最慢，但已知PYP的激发态衰减却很小，但用于生产性光循环进入的量子产率与Hhal PYP非常相似。 Pro68在PYP中高度保守，对于Hhal PIT中的高光化学量子产率非常重要，但是该残基在野生型Lbif PIT中是Ile。 I68P Lbif PYP中光产物形成的水平略有增加，表明该残基调节整个PIT家族中的光化学量子产率。 Lbif PYP还显示了蓝移的光产物，该产物以前在PYP的超快速研究中未被发现，我们将其命名为pUV。我们假设pUV是扭曲的质子化pCAH配置的PIT光循环中的绕道。用Hhal PIT进行的冰冻运动实验证实了pUV的存在，但是在室温超快实验中这种状态的数量非常少。这些结果解决了有关PYP室温光循环中分叉的存在的文献中长期存在的矛盾。

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