Integration of Temperature and Blue-Light Sensing in Acinetobacter baumannii Through the BlsA Sensor

VALLE LORENA; CABRUJA M.; MUSSI M. A.; ABATEDAGA INÉS; MÜLLER G.L.; JAIME P.; GOLIC A.E.; MORÁN VIEYRA F.; BORSARELLI C.

Cordoba

Congreso; XIII Encuentro Latinoamericano de Fotoquímica y Fotobiología (XIII ELAFOT); 2017

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. 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.This work has been supported in part by grants from Agencia Nacional de Promoción Científica y Tecnológica de Argentina (PICT 2012-2666, PICTO-UNSE 2012-0013, PICT 2013-0018 and CT 2014-1161).35