Instituto de Bionanotecnología del NOA (INBIONATEC), Universidad Nacional de Santiago del Estero (UNSE), CONICET, Santiago del Estero, Argentina.
Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET), Universidad Nacional de Rosario (UNR), Rosario, Argentina.
Photochem Photobiol. 2017 May;93(3):805-814. doi: 10.1111/php.12760.
BlsA is a BLUF photoreceptor present in Acinetobacter baumannii, responsible for modulation of motility, biofilm formation and virulence by light. In this work, we have combined physiological and biophysical evidences to begin to understand the basis of the differential photoregulation observed as a function of temperature. Indeed, we show that blsA expression is reduced at 37°C, which correlates with negligible photoreceptor levels in the cells, likely accounting for absence of photoregulation at this temperature. Another point of control occurs on the functionality of the BlsA photocycle itself at different temperatures, which occurs with an average quantum yield of photoactivation of the signaling state of 0.20 ± 0.03 at 15°C < T < 25°C, but is practically inoperative at T > 30°C, as a result of conformational changes produced in the nanocavity of FAD. This effect would be important when the photoreceptor is already present in the cell to avoid almost instantaneously further signaling process when it is no longer necessary, for example under circumstances of temperature changes possibly faced by the bacteria. This complex interplay between light and temperature would provide the bacteria clues of environmental location and dictate/modulate light photosensing in A. baumannii.
BlsA 是鲍曼不动杆菌中的一种 BLUF 光受体，负责通过光照调节运动性、生物膜形成和毒力。在这项工作中，我们结合生理和生物物理证据，开始理解温度依赖性光调节差异的基础。事实上，我们表明，blsA 的表达在 37°C 时减少，这与细胞中几乎不存在光受体水平相关，这可能是在该温度下不存在光调节的原因。另一个控制点是不同温度下 BlsA 光循环本身的功能，在 15°C<T<25°C 时，其信号状态的光激活量子产率平均为 0.20±0.03，但在 T>30°C 时实际上不起作用，这是由于 FAD 纳米腔中产生的构象变化所致。当光受体已经存在于细胞中时，这种效应很重要，以避免在不再需要时几乎立即进行进一步的信号传递过程，例如在细菌可能面临的温度变化情况下。这种光和温度之间的复杂相互作用将为细菌提供环境位置的线索，并在鲍曼不动杆菌中决定/调节光感测。
