IADR Abstract Archives
Catecholamines Induce Genes Involved in Anaerobic Respiration and Oxidative Stress in Aggregatibacter actinomycetemcomitans
Objectives:
To determine if the qseBC two-component sytem in Aggregatibacter actinomycetemcomitans (Aa) responds to catecholamines (CAT) and/or ferrous iron or both (CAT-Fe), and if there are any physiological changes associated with CAT-Fe exposure.
Methods:
Aa was grown in a chemically defined media and supplemented with either ferrous chloride (100uM) and/or norepinephrine (50uM) or epinephrine (50uM). Expression of the ygiW-qseBC operon was measured using a lacZ reporter plasmid containing the ygiW-qseBC operon promoter. Changes in growth were measured by OD600. In addition, RNA was harvested at mid-log phase and hybridized to a custom Aa microarray. Results were confirmed by qRT-PCR and various biochemical assays.
Results:
Expression of qseBC was slightly induced by CAT or ferrous iron, but significantly increased in the presence of CAT-Fe. In addition, we show that Aa growth is enhanced in the presence of CAT-Fe. In the microarray, 185 genes were differentially regulated in the presence of norepinephrine, 228 genes in the presence of CAT-Fe, and 63 of these genes appeared in both arrays. The results were confirmed by qRT-PCR. Many of the genes that were highly induced in the presence of CAT or CAT-Fe encoded proteins involved in oxidative stress (e.g. catalase and oxyR) and anaerobic respiration (e.g. formate dehydrogenase, DMSO reductase and nitrate and nitrite reductases). A formate assay and an MTT reduction assay were used to confirm results.
Conclusions:
Exposure of Aa to CAT-Fe causes significant changes in gene transcription and growth. It is interesting to note that many of the CAT induced genes correspond to pathways that have been shown to be up-regulated in an in vivo model of Aa infection suggesting that the detection of CAT may contribute to adaptation of Aa to the host environment.
To determine if the qseBC two-component sytem in Aggregatibacter actinomycetemcomitans (Aa) responds to catecholamines (CAT) and/or ferrous iron or both (CAT-Fe), and if there are any physiological changes associated with CAT-Fe exposure.
Methods:
Aa was grown in a chemically defined media and supplemented with either ferrous chloride (100uM) and/or norepinephrine (50uM) or epinephrine (50uM). Expression of the ygiW-qseBC operon was measured using a lacZ reporter plasmid containing the ygiW-qseBC operon promoter. Changes in growth were measured by OD600. In addition, RNA was harvested at mid-log phase and hybridized to a custom Aa microarray. Results were confirmed by qRT-PCR and various biochemical assays.
Results:
Expression of qseBC was slightly induced by CAT or ferrous iron, but significantly increased in the presence of CAT-Fe. In addition, we show that Aa growth is enhanced in the presence of CAT-Fe. In the microarray, 185 genes were differentially regulated in the presence of norepinephrine, 228 genes in the presence of CAT-Fe, and 63 of these genes appeared in both arrays. The results were confirmed by qRT-PCR. Many of the genes that were highly induced in the presence of CAT or CAT-Fe encoded proteins involved in oxidative stress (e.g. catalase and oxyR) and anaerobic respiration (e.g. formate dehydrogenase, DMSO reductase and nitrate and nitrite reductases). A formate assay and an MTT reduction assay were used to confirm results.
Conclusions:
Exposure of Aa to CAT-Fe causes significant changes in gene transcription and growth. It is interesting to note that many of the CAT induced genes correspond to pathways that have been shown to be up-regulated in an in vivo model of Aa infection suggesting that the detection of CAT may contribute to adaptation of Aa to the host environment.