Characterization of BLUF-photoreceptors present in Acinetobacter nosocomialis

PÉREZ MORA, BÁRBARA; BIANCOTTI, DAIANA ; MUSSI, MARÍA ALEJANDRA; TUTTOBENE, MARISEL; BORSARELLI, CLAUDIO D.; ABATEDAGA, INÉS; MÜLLER, GABRIELA L.; VALLE, LORENA

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2022 vol. 17 p. 1 - 27

1932-6203

Acinetobacter nosocomialis is a Gram-negative opportunistic pathogen, whose ability tocause disease in humans is well recognized. Blue light has been shown to modulate important physiological traits related to persistence and virulence in this microorganism. In thiswork, we characterized the three Blue Light sensing Using FAD (BLUF) domain-containingproteins encoded in the A. nosocomialis genome, which account for the only canonical lightsensors present in this microorganism. By focusing on a light-modulated bacterial processsuch as motility, the temperature dependence of light regulation was studied, as well as theexpression pattern and spectroscopic characteristics of the different A. nosocomialisBLUFs. Our results show that the BLUF-containing proteins AnBLUF65 and AnBLUF46encode active photoreceptors in the light-regulatory temperature range when expressedrecombinantly. In fact, AnBLUF65 is an active photoreceptor in the temperature range from15˚C to 37˚C, while AnBLUF46 between 15˚C to 32˚C, in vitro. In vivo, only the Acinetobacter baumannii BlsA?s ortholog AnBLUF65 was expressed in A. nosocomialis cells recoveredfrom motility plates. Moreover, complementation assays showed that AnBLUF65 is able tomediate light regulation of motility in A. baumannii ΔblsA strain at 30˚C, confirming its roleas photoreceptor and in modulation of motility by light. Intra-protein interactions analyzedusing 3D models built based on A. baumannii´s BlsA photoreceptor, show that hydrophobic/aromatic intra-protein interactions may contribute to the stability of dark/light- adapted statesof the studied proteins, reinforcing the previous notion on the importance of these interactions in BLUF photoreceptors. Overall, the results presented here reveal the presence ofBLUF photoreceptors in A. nosocomialis with idiosyncratic characteristics respect to the previously characterized A. baumannii?s BlsA, both regarding the photoactivity temperaturedependency as well as expression patterns, contributing thus to broaden our knowledge onthe BLUF family.