Identification of iron regulated genes in the fish pathogen Aeromonas salmonicida subsp. salmonicida: Genetic diversity and evidence of conserved iron uptake systems

Najimi, Mohsen; Lemos, Manuel L.; Osorio, Carlos R.

doi:10.1016/j.vetmic.2008.07.008

Cited by 25 publications

(23 citation statements)

References 23 publications

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“…In Aeromonas , as in other bacterial pathogens, the mechanism for obtaining iron can be siderophore dependent or siderophore independent (Janda ; Najimi et al . , ; Chopra et al . ).…”

Section: Virulence Factorsmentioning

confidence: 97%

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Aeromonas spp. whole genomes and virulence factors implicated in fish disease

Beaz-Hidalgo

Figueras

2013

Journal of Fish Diseases

249

187

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It is widely recognized that Aeromonas infections produce septicaemia, and ulcerative and haemorrhagic diseases in fish, causing significant mortality in both wild and farmed freshwater and marine fish species that damage the economics of the aquaculture sector. The descriptions of the complete genomes of Aeromonas species have allowed the identification of an important number of virulence genes that affect the pathogenic potential of these bacteria. This review will focus on the most relevant information derived from the available Aeromonas genomes in relation to virulence and on the diverse virulence factors that actively participate in host adherence, colonization and infection, including structural components, extracellular factors, secretion systems, iron acquisition and quorum sensing mechanisms.

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“…In Aeromonas , as in other bacterial pathogens, the mechanism for obtaining iron can be siderophore dependent or siderophore independent (Janda ; Najimi et al . , ; Chopra et al . ).…”

Section: Virulence Factorsmentioning

confidence: 97%

“…Iron is an essential nutrient for most bacteria, and in fact, many pathogenic bacteria depend on the acquisition of iron for their survival within the host, contributing significantly to their virulence (Hirst, Hastings & Ellis ; Janda ; Najimi, Lemos & Osorio , ; Chopra et al . ).…”

Section: Virulence Factorsmentioning

confidence: 99%

Aeromonas spp. whole genomes and virulence factors implicated in fish disease

Beaz-Hidalgo

Figueras

2013

Journal of Fish Diseases

249

187

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“…Furthermore, the amonabactin receptor of A. hydrophila shows low specificity, permitting the transport of an extraordinary ample range of siderophores, with various chelating groups like catecholate, hidroxamate and hydroxypyroridone [108]. Recently, the A. salmonicida gene cluster involved in the catechol-type siderophore biosynthesis has been described [112]. Using a proteomic approach, a recent study demonstrated that under iron-limited conditions A. salmonicida expresses three iron-regulated outer membrane receptors, and one of these receptors was proposed to be a putative heme receptor based on sequence homology [113].…”

Section: Iron-binding Systemsmentioning

confidence: 99%

“…A genetic screening known as the Fur titration assay on this bacterium identify Fur-regulated genes for siderophore biosynthesis and for ferrisiderophore transport previously described. A screening of gene distribution demonstrated that all the analyzed strains shared genes for siderophore biosynthesis and transport and for heme utilization, indicating that these two systems of iron acquisition are a conserved trait [112]. Iron-regulated A. salmonicida proteins have demonstrated to be protective antigens for fish and are good candidates for the improvement of vaccines [117].…”

Section: Iron-binding Systemsmentioning

confidence: 99%

The MainAeromonasPathogenic Factors

2012

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The members of the Aeromonas genus are ubiquitous, water-borne bacteria. They have been isolated from marine waters, rivers, lakes, swamps, sediments, chlorine water, water distribution systems, drinking water and residual waters; different types of food, such as meat, fish, seafood, vegetables, and processed foods. Aeromonas strains are predominantly pathogenic to poikilothermic animals, and the mesophilic strains are emerging as important pathogens in humans, causing a variety of extraintestinal and systemic infections as well as gastrointestinal infections. The most commonly described disease caused by Aeromonas is the gastroenteritis; however, no adequate animal model is available to reproduce this illness caused by Aeromonas. The main pathogenic factors associated with Aeromonas are: surface polysaccharides (capsule, lipopolysaccharide, and glucan), S-layers, iron-binding systems, exotoxins and extracellular enzymes, secretion systems, fimbriae and other nonfilamentous adhesins, motility and flagella.

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“…For example, molecules associated with the quorum sensing system have been described [25,26] and shown to play a role in regulating the production of proteases [26] including Asap1 [27]. Similarly, a correlation was demonstrated between iron depletion and the production of virulence factors such as superoxide-dismutase [28], hemin receptor HutE, and the expression levels of genes encoding a putative DapD and Flp/Fap-pilin proteins [29]. Finally, three iron-regulated outer membrane proteins (IROMPs) have been described in A. salmonicida [30], all were TonB dependent: The first IROMP was a ferric siderophore receptor of 85 kDa in size while the second was identified as a colicin receptor homologue (FstC) of 73 kDa and likely to also act as a ferric receptor homologue.…”

Section: Introductionmentioning

confidence: 99%

Protein expression and transcription profiles of three strains of Aeromonas salmonicida ssp. salmonicida under normal and iron-limited culture conditions

et al. 2014

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BackgroundAeromonas salmonicida is an important fish pathogen that produces a wide and varied array of virulence factors. Here we used iron deprivation by addition of the chelator 2’2-dipyridyl to induce the expression of several such virulence factors in three isolates of Aeromonas salmonicida (one avirulent and two virulent). By using SDS-PAGE followed by mass spectrometry, we identified proteins that appeared differentially expressed under these conditions. The differential transcription of the identified gene products were subsequently measured by reverse transcription quantitative real-time PCR (RT-qPCR).ResultsOur initial screening using SDS-PAGE identified five proteins that appeared differentially expressed in virulent and avirulent isolates or, within the same isolates, between bacteria cultivated under iron-rich or iron-deprived conditions. The transcription of the genes coding for these proteins were subsequently quantified by RT-qPCR. Results of this analysis demonstrated that the gene coding for alkyl hydroperoxide reductase (AhpC), a protein involved in oxidative stress response, was transcribed at a higher rate in the virulent strain as compared to the avirulent strain. Additionally, it was observed that addition of an iron chelator to the culture medium lead to a reduction of the transcription levels of the regulatory histone-like nucleoid structuring protein (H-NS). This was consistent in all three isolates. On the other hand, the transcription levels of the virulence array protein (VapA) and the protein ATP-synthetase F (ATPF) displayed only limited changes, despite being the dominant component of a protein fraction that displayed changes during the preliminary SDS-PAGE screening. This was true regardless of the culture conditions and of the isolates considered. Finally, transcription of the enzyme enolase was upregulated in the iron-deprived broths in all isolates.ConclusionsWe identified several genes differentially expressed under culture conditions known to lead to the overexpression of virulence factors. In addition, we identified alkyl hydroperoxide as being overexpressed in the virulent isolates compared to the avirulent isolates. The results from this study will contribute to enhance our understanding of the virulence of A. salmonicida and may suggest new directions for further research.

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Identification of iron regulated genes in the fish pathogen Aeromonas salmonicida subsp. salmonicida: Genetic diversity and evidence of conserved iron uptake systems

Cited by 25 publications

References 23 publications

Aeromonas spp. whole genomes and virulence factors implicated in fish disease

Aeromonas spp. whole genomes and virulence factors implicated in fish disease

The MainAeromonasPathogenic Factors

Protein expression and transcription profiles of three strains of Aeromonas salmonicida ssp. salmonicida under normal and iron-limited culture conditions

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