Enterohaemorrhagic Escherichia coli activates nitrate respiration to benefit from the inflammatory response for initiation of microcolony-formation
Background: For successful colonization, enterohaemorrhagic Escherichia coli (EHEC) injects virulence factors, called effectors, into target cells through the type three secretion system (T3SS), which is composed of a needle and basal body. Under anaerobic conditions, the T3SS machinery remains immature and does not have a needle structure. However, activation of nitrate respiration enhances the completion of the T3SS machinery. Because nitric oxide released by the host inflammatory response increases nitrate concentration, we sought to determine the effect of the inflammatory response on initiation of EHEC microcolony-formation.
Results: The colony-forming capacity was increased in accordance with the increase of nitrate in the medium. The addition of the nitric oxide-producing agent NOR-4 also enhanced the adherence capacity, which was dependent on nitrate reductase encoded by the narGHJI genes. Culture supernatant of epithelial cells, which was stimulated by a cytokine mixture, enhanced the colony-forming capacity of wild-type EHEC but not of the narGHJI mutant. Finally, colony formation by wild-type EHEC on epithelial cells, which were preincubated with heat-killed bacteria, was higher than the narGHJI mutant, and this effect was abolished by aminoguanidine hydrochloride, which is an iNOS (inducible nitric oxide synthase) inhibitor.
Conclusions: These results indicate that the inflammatory response enhances EHEC adherence by increasing nitrate concentration.
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Posted 17 Aug, 2020
On 20 Aug, 2020
On 12 Aug, 2020
On 12 Aug, 2020
On 10 Aug, 2020
On 04 Aug, 2020
On 21 Jul, 2020
On 20 Jul, 2020
On 20 Jul, 2020
Posted 29 Jul, 2020
On 06 Aug, 2020
On 05 Aug, 2020
On 05 Aug, 2020
On 10 Jul, 2020
Received 09 Jul, 2020
On 26 Jun, 2020
Received 06 Apr, 2020
On 28 Mar, 2020
Invitations sent on 27 Mar, 2020
On 23 Mar, 2020
On 20 Mar, 2020
On 19 Mar, 2020
Enterohaemorrhagic Escherichia coli activates nitrate respiration to benefit from the inflammatory response for initiation of microcolony-formation
Posted 17 Aug, 2020
On 20 Aug, 2020
On 12 Aug, 2020
On 12 Aug, 2020
On 10 Aug, 2020
On 04 Aug, 2020
On 21 Jul, 2020
On 20 Jul, 2020
On 20 Jul, 2020
Posted 29 Jul, 2020
On 06 Aug, 2020
On 05 Aug, 2020
On 05 Aug, 2020
On 10 Jul, 2020
Received 09 Jul, 2020
On 26 Jun, 2020
Received 06 Apr, 2020
On 28 Mar, 2020
Invitations sent on 27 Mar, 2020
On 23 Mar, 2020
On 20 Mar, 2020
On 19 Mar, 2020
Background: For successful colonization, enterohaemorrhagic Escherichia coli (EHEC) injects virulence factors, called effectors, into target cells through the type three secretion system (T3SS), which is composed of a needle and basal body. Under anaerobic conditions, the T3SS machinery remains immature and does not have a needle structure. However, activation of nitrate respiration enhances the completion of the T3SS machinery. Because nitric oxide released by the host inflammatory response increases nitrate concentration, we sought to determine the effect of the inflammatory response on initiation of EHEC microcolony-formation.
Results: The colony-forming capacity was increased in accordance with the increase of nitrate in the medium. The addition of the nitric oxide-producing agent NOR-4 also enhanced the adherence capacity, which was dependent on nitrate reductase encoded by the narGHJI genes. Culture supernatant of epithelial cells, which was stimulated by a cytokine mixture, enhanced the colony-forming capacity of wild-type EHEC but not of the narGHJI mutant. Finally, colony formation by wild-type EHEC on epithelial cells, which were preincubated with heat-killed bacteria, was higher than the narGHJI mutant, and this effect was abolished by aminoguanidine hydrochloride, which is an iNOS (inducible nitric oxide synthase) inhibitor.
Conclusions: These results indicate that the inflammatory response enhances EHEC adherence by increasing nitrate concentration.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5