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Supplementary Material 3

June 2018

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CC BY 4.0

Authors:

Felipe Velasquez

University of Chile

Fernando A. Amaya

University of Chile

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Figure S2.- Mass spectrometry analysis of lipid A species produced by S. Enteritidis ∆arcA

mutant. Lipid A samples were obtained from cultures of a ∆arcA mutant (Silva-Valenzuela et al., 2016.

doi: 10.1016/j.bbrc.2016.06.074) grown under aerobic conditions. MALDI-TOF mass spectrometry

analysis of lipid A preparations was performed and experimental m/z values are indicated.

1717

1734

1798

1813

2052

1587 1828

30

60

90

Relative intensity

1500 1800 2100

m/z

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Fnr and ArcA Regulate Lipid A Hydroxylation in Salmonella Enteritidis by Controlling lpxO Expression in Response to Oxygen Availability

Article

June 2018

Paulina A. Fernández · Felipe Velasquez · Héctor Garcias-Papayani · Fernando A. Amaya · Sergio A Álvarez

Data

Full-text available

Supplementary Material 1

June 2018

Article

Full-text available

Fnr and ArcA Regulate Lipid A Hydroxylation in Salmonella Enteritidis by Controlling lpxO Expression...

June 2018 · Frontiers in Microbiology

Lipid A is the bioactive component of lipopolysaccharide, and presents a dynamic structure that undergoes modifications in response to environmental signals. Many of these structural modifications influence Salmonella virulence. This is the case of lipid A hydroxylation, a modification catalyzed by the dioxygenase LpxO. Although it has been established that oxygen is required for lipid A ... [Show full abstract] hydroxylation acting as substrate of LpxO in Salmonella, an additional regulatory role for oxygen in lpxO expression has not been described. The existence of this regulation could be relevant considering that Salmonella faces low oxygen tension during infection. This condition leads to an adaptive response by changing the expression of numerous genes, and transcription factors Fnr and ArcA are major regulators of this process. In this work, we describe for the first time that lipid A hydroxylation and lpxO expression are modulated by oxygen availability in Salmonella enterica serovar Enteritidis (S. Enteritidis). Biochemical and genetic analyses indicate that this process is regulated by Fnr and ArcA controlling the expression of lpxO. In addition, according to our results, this regulation occurs by direct binding of both transcription factors to specific elements present in the lpxO promoter region. Altogether, our observations revealed a novel role for oxygen acting as an environment signal controlling lipid A hydroxylation in S. Enteritidis.

Data

Full-text available

Supplementary Material 2

June 2018

Article

O-antigen chain-length distribution in Salmonella enterica serovar Enteritidis is regulated by oxyge...

June 2016 · Biochemical and Biophysical Research Communications

Lipopolysaccharide (LPS) consists of three covalently linked domains: the lipid A, the core region and the O antigen (OAg), consisting of repeats of an oligosaccharide. S. Enteritidis produces a LPS with two OAg preferred chain lengths: a long (L)-OAg controlled by WzzSE and a very long (VL)-OAg controlled by WzzfepE. In this work, we show that OAg produced by S. Enteritidis grown in E minimal ... [Show full abstract] medium also presented two preferred chain-lengths. However, a simultaneous and opposing change in the production of L-OAg and VL-OAg was observed in response to oxygen availability. Biochemical and genetics analyses indicate that this process is regulated by transcriptional factors Fnr and ArcA by means of controlling the transcription of genes encoding WzzSE and WzzfepE in response to oxygen availability. Thus, our results revealed a sophisticated regulatory mechanism involved in the adaptation of S. Enteritidis to one of the main environmental cues faced by this pathogen during infection.