Quorum sensing network in clinical strains of A. baumannii: AidA is a new quorum quenching enzyme.
Acinetobacter baumannii is an important pathogen that causes nosocomial infections generally associated with high mortality and morbidity in Intensive Care Units (ICUs). Currently, little is known about the Quorum Sensing (QS)/Quorum Quenching (QQ) systems of this pathogen. We analyzed these mechanisms in seven clinical isolates of A. baumannii. Microarray analysis of one of these clinical isolates, Ab1 (A. baumannii ST-2_clon_2010), previously cultured in the presence of 3-oxo-C12-HSL (a QS signalling molecule) revealed a putative QQ enzyme (α/ß hydrolase gene, AidA). This QQ enzyme was present in all non-motile clinical isolates (67% of which were isolated from the respiratory tract) cultured in nutrient depleted LB medium. Interestingly, this gene was not located in the genome of the only motile clinical strain growing in this medium (A. baumannii strain Ab421_GEIH-2010 [Ab7], isolated from a blood sample). The AidA protein expressed in E. coli showed QQ activity. Finally, we observed downregulation of the AidA protein (QQ system attenuation) in the presence of H2O2 (ROS stress). In conclusion, most of the A. baumannii clinical strains were not surface motile (84%) and were of respiratory origin (67%). Only the pilT gene was involved in surface motility and related to the QS system. Finally, a new QQ enzyme (α/ß hydrolase gene, AidA protein) was detected in these strains.
Department of Microbiology, Complejo Hospitalario Universitario A Coruña (CHUAC)-INIBIC, A Coruña, Spain.|Spanish Network for Research in Infectious Diseases (REIPI), Virgen Macarena, Seville, Spain.
María
M
López
Department of Microbiology, Faculty of Biology-CIBUS, University of Santiago de Compostela, Santiago de Compostela, Spain.
Celia
C
Mayer
Department of Microbiology, Complejo Hospitalario Universitario A Coruña (CHUAC)-INIBIC, A Coruña, Spain.
Laura
L
Fernández-García
Department of Microbiology, Complejo Hospitalario Universitario A Coruña (CHUAC)-INIBIC, A Coruña, Spain.
Lucía
L
Blasco
Department of Microbiology, Faculty of Biology-CIBUS, University of Santiago de Compostela, Santiago de Compostela, Spain.
Andrea
A
Muras
Biological Research Center (CIB-CSIC), Madrid, Spain.
Federico Martín
FM
Ruiz
Department of Microbiology, Complejo Hospitalario Universitario A Coruña (CHUAC)-INIBIC, A Coruña, Spain.|Spanish Network for Research in Infectious Diseases (REIPI), Virgen Macarena, Seville, Spain.
German
G
Bou
Department of Microbiology, Faculty of Biology-CIBUS, University of Santiago de Compostela, Santiago de Compostela, Spain.
Ana
A
Otero
Department of Microbiology, Complejo Hospitalario Universitario A Coruña (CHUAC)-INIBIC, A Coruña, Spain.|Spanish Network for Research in Infectious Diseases (REIPI), Virgen Macarena, Seville, Spain.
María
http://orcid.org/0000-0003-4501-0387
M
Tomás
D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000235:genetics; D040981:Acinetobacter baumannii / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D003428:Cross Infection / Q000235:genetics / Q000382:microbiology; D015536:Down-Regulation / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D006714:Homoserine / Q000031:analogs & derivatives / Q000235:genetics; D053038:Quorum Sensing / Q000235:genetics*
D001426:Bacterial Proteins; C109860:N-(3-oxododecanoyl)homoserine lactone; D006714:Homoserine; D015107:4-Butyrolactone