BfmRS encodes a regulatory system involved in light signal transduction modulating motility and desiccation tolerance in the human pathogen Acinetobacter baumannii

Abstract

We have previously shown that Acinetobacter baumannii as well as other relevant clinical bacterial pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa, perceive and respond to light at 37 °C, the normal temperature in mammal hosts. In this work, we present evidence indicating that the two-component system BfmRS transduces a light signal in A. baumannii at this temperature, showing selective involvement of the BfmR and BfmS components depending on the specific cellular process. In fact, both BfmR and BfmS participate in modulation of motility by light, while only BfmR is involved in light regulation of desiccation tolerance in this microorganism. Neither BfmR nor BfmS contain a photoreceptor domain and then most likely, the system is sensing light indirectly. Intriguingly, this system inhibits blsA expression at 37 °C, suggesting antagonistic functioning of both signaling systems. Furthermore, we present evidence indicating that the phosphorylatable form of BfmR represses motility. Overall, we provide experimental evidence on a new biological function of this multifaceted system that broadens our understanding of A. baumannii’s physiology and responses to light.

Molecular mechanism of siderophore regulation by the Pseudomonas aeruginosa BfmRS two-component system in response to osmotic stress

“…BfmR has been shown to be crucial for pellicle and biofilm formation in Acinetobacter baumannii and P. aeruginosa 24 , 27 . Additionally, it plays a pivotal role in the bacterium’s survival at the mammalian host temperature in multiple animal models, contributing significantly to chronic infections 25 , 26 , 29 . It has been reported that BfmR has a potential extensive downstream regulatory network, and BfmS influences the tolerance to certain antibiotics, outer membrane vesicle (OMV) production, and cytotoxicity toward host cells 43 .…”

“…It has been reported that BfmR has a potential extensive downstream regulatory network, and BfmS influences the tolerance to certain antibiotics, outer membrane vesicle (OMV) production, and cytotoxicity toward host cells 43 . Studies have also begun to shed light on the signals sensed by BfmS, such as light or pressure 29 . Despite these advances, a comprehensive understanding of its complete functional repertoire and its intricate regulatory mechanisms in complex biological processes remains an area necessitating further exploration.…”

Genome Sequence of Clinical Acinetobacter baumannii Strain V15

“…V15 forms robust biofilms, produces a capsule, and generates large amounts of extracellular compounds ( 5 ). Moreover, it responds to light at both environmental temperatures and those of warm-blooded hosts ( 6 ). Furthermore, V15 is sensitive to multiple antibiotics and genetically manipulable.…”

Roles of DJ41_1407 and DJ41_1408 in Acinetobacter baumannii ATCC19606 Virulence and Antibiotic Response

“…baumannii commonly employs two-component systems (TCSs) to regulate adaptive responses and virulence-related traits. Most TCSs in bacteria can regulate gene expression related to antibiotic resistance, virulence, biofilm formation [8], and motility [9], and 16 sensor kinases and 17 response regulators have been annotated in A. baumannii to date, with studies previously conducted on one hybrid sensor kinase, A1S_2811 [10], and nine TCS, AdeSR [11], BaeSR [12], BfmSR [13], CntAB [14], EmaSR [15], GacSA [16], OmpR-EnvZ [17,18], PmrAB [19], and StkSR [20] (AmsSR [21]). Of these TCSs, many were found to regulate gene expression related to antibiotic resistance.…”