ABC transporter transcription regulation by Staphylococcus aureus SAOUHSC01313-01314 Two Component System

ALEJANDRA RAQUEL DIAZ; DIEGO DE MENDOZA; MARIA CECILIA MANSILLA

Buenos Aires

Congreso; LIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2017

SAIB

Staphylococcusaureus, a G+bacterium, is a frequent component of human microbiota that can turn into adangerous pathogen. The pathogenicity of this bacterium is caused by expressionof a myriad of virulence factors. Since two component systems (TCSs) are the principal mechanism involved in stressresponse, we studied two contiguous genes located in strain NCTC 8325,SAOUHSC01313-01314, coding for a membrane-histidine kinase (HK) and a responseregulator, respectively. These genes showed homology with Bacillus subtilis DesKR,which regulates transcription of its sole desaturase in response to changes inmembrane fluidity. The TCSsa is located downstream of genes encoding a putativeABC transporter (SAOUHSC01311-SAOUHSC01312) that carries in its promoter a boxvery similar to the regulatory region of des. This TCS/ABC link resemblesthe prototype detoxification module found in Firmicutes. In order tostudy the transcriptional activation of the ABC transporter by the TCS weconstructed a transcriptional fusion of SAOUHSC01311 promoter to lacZ,in plasmid pTCVlac. This plasmid, pARD22, was transformed in wild type strainsRN4220 and SH1000, and the derivatives ΔSAOUHSC01313-01314,strains ARD10 and ARD11, respectively. β-gal assaysof strains carrying pARD22 were conducted at different temperatures and mediacomposition. We found that the TCSsa regulates the transcription of the genes encodingthe ABC transporter in a temperature dependent fashion. However, in contrast tothe des gene, transcription was induced at 37°C rather than at lowtemperature. We also found that expression of the ABC transporter occurs instationary phase, and requires minerals and sugars in the culture medium. Theseresults show that, despite the similarity between DesK and SAOUHSC01313, theHKsa responds to different stimuli, and shed light on the possible role of thisHK in the membrane of S aureus exposed to environment cues verydifferent from those that B subtilis faces in its environment.