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Aggregatibacter actinomycetemcomitans Qse BC is activated by catecholamines and iron and regulates genes encoding proteins associated with anaerobic respiration and metabolism
Author(s) -
Weigel W.A.,
Demuth D.R.,
TorresEscobar A.,
JuárezRodríguez M.D.
Publication year - 2015
Publication title -
molecular oral microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 77
eISSN - 2041-1014
pISSN - 2041-1006
DOI - 10.1111/omi.12101
Subject(s) - biology , gene , operon , regulon , genetics , periplasmic space , microbiology and biotechnology , gene expression , escherichia coli
Summary Aggregatibacter actinomycetemcomitans Qse BC regulates its own expression and is essential for biofilm growth and virulence. However, the signal that activates the QseC sensor has not been identified and the qse BC regulon has not been defined. In this study, we show that QseC is activated by catecholamine hormones and iron but not by either component alone. Activation of QseC requires an EYRDD motif in the periplasmic domain of the sensor and site‐specific mutations in EYRDD or the deletion of the periplasmic domain inhibits catecholamine/iron‐dependent induction of the ygiW‐qse BC operon. Catecholamine/iron‐dependent induction of transcription also requires interaction of the QseB response regulator with its binding site in the ygiW‐qse BC promoter. Whole genome microarrays were used to compare gene expression profiles of A. actinomycetemcomitans grown in a chemically defined medium with and without catecholamine and iron supplementation. Approximately 11.5% of the A. actinomycetemcomitans genome was differentially expressed by at least two‐fold upon exposure to catecholamines and iron. The expression of ferritin was strongly induced, suggesting that intracellular iron storage capacity is increased upon Qse BC activation. Consistent with this, genes encoding iron binding and transport proteins were down‐regulated by Qse BC . Strikingly, 57% of the Qse BC up‐regulated genes (56/99) encode proteins associated with anaerobic metabolism and respiration. Most of these up‐regulated genes were recently reported to be induced during in vivo growth of A. actinomycetemcomitans . These results suggest that detection of catecholamines and iron by Qse BC may alter the cellular metabolism of A. actinomycetemcomitans for increased fitness and growth in an anaerobic host environment.