Characterization of the Urease Operon of
            <i>Brucella abortus</i>
            and Assessment of Its Role in Virulence of the Bacterium

Sangari, Félix J.; Seoane, Asunción; Rodrı́guez, Marı́a C.; Agüero, Jesús; Lobo, Juan M. García

doi:10.1128/iai.01244-06

Cited by 116 publications

(135 citation statements)

References 43 publications

(29 reference statements)

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“…In order for proper assembly of the urease metallocenter, all four of the accessory proteins must be functional. Although urease has been demonstrated to be an important virulence factor in a number of bacteria, such as Helicobacter pylori (11), Yersinia enterocolitica (10), Proteus mirabilis (9), Brucella species (1,45), and Klebsiella pneumoniae (27), the role of urease in EHEC pathogenesis is not defined. It is possible that, like some other bacteria, EHEC exploits the enzyme urease as an additional factor to aid with surviving the low pH conditions as it passes through the stomach.…”

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confidence: 99%

Functional and Phylogenetic Analysis of ureD in Shiga Toxin-Producing Escherichia coli

2011

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Enterohemorrhagic Escherichia coli (EHEC) is a food-borne pathogen that can cause severe health complications and utilizes a much lower infectious dose than other E. coli pathotypes. Despite having an intact ure locus, ureDABCEFG, the majority of EHEC strains are phenotypically urease negative under tested conditions. Urease activity potentially assists with survival fitness by enhancing acid tolerance during passage through the stomach or by aiding with colonization in either human or animal reservoirs. Previously, in the EHEC O157:H7 Sakai strain, a point mutation in ureD, encoding a urease chaperone protein, was identified, resulting in a substitution of an amber stop codon for glutamine. This single nucleotide polymorphism (SNP) is observed in the majority of EHEC O157:H7 isolates and correlates with a negative urease phenotype in vitro. We demonstrate that the lack of urease activity in vitro is not solely due to the amber codon in ureD. Our analysis has identified two additional SNPs in ureD affecting amino acid positions 38 and 205, in both cases determining whether the encoded amino acid is leucine or proline. Phylogenetic analysis based on Ure protein sequences from a variety of urease-encoding bacteria demonstrates that the proline at position 38 is highly conserved among Gram-negative bacteria. Experiments reveal that the L38P substitution enhances urease enzyme activity; however, the L205P substitution does not. Multilocus sequence typing analysis for a variety of Shiga toxin-producing E. coli isolates combined with the ureD sequence reveals that except for a subset of the O157:H7 strains, neither the in vitro urease-positive phenotype nor the ureD sequence is phylogenetically restricted.

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confidence: 99%

Functional and Phylogenetic Analysis of ureD in Shiga Toxin-Producing Escherichia coli

2011

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“…While the T4SS is required for intracellular survival and replication, defects in LPS structure that eliminate O antigen result in a number of phenotypes, including sensitivity to complement-mediated killing, increased sensitivity to killing by antimicrobial peptides, increased maturation of dendritic cells, and attenuation in tissue culture and animal infection models (9,25,31). Recent studies have demonstrated a potential role of urease and bile salt hydrolase in oral infection by Brucella abortus and Brucella suis in mice (4,18,52). However, the roles of T4SS and LPS during B. melitensis infection via the digestive tract are not known.…”

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confidence: 99%

Establishment of Systemic Brucella melitensis Infection through the Digestive Tract Requires Urease, the Type IV Secretion System, and Lipopolysaccharide O Antigen

Paixão

Roux²,

Hartigh³

et al. 2009

Infect Immun

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Human brucellosis is caused mainly by Brucella melitensis, which is often acquired by ingesting contaminated goat or sheep milk and cheese. Bacterial factors required for food-borne infection of humans by B. melitensis are poorly understood. In this study, a mouse model of oral infection was characterized to assess the roles of urease, the VirB type IV secretion system, and lipopolysaccharide for establishing infection through the digestive tract. B. melitensis strain 16M was consistently recovered from the mesenteric lymph node (MLN), spleen, and liver beginning at 3 or 7 day postinfection (dpi). In the gut, persistence of the inoculum was observed up to 21 dpi. No inflammatory lesions were observed in the ileum or colon during infection. Mutant strains lacking the ureABC genes of the ure1 operon, virB2, or pmm encoding phosphomannomutase were constructed and compared to the wild-type strain for infectivity through the digestive tract. Mutants lacking the virB2 and pmm genes were attenuated in the spleen (P < 0.05) and MLN (P < 0.001), respectively. The wild-type and mutant strains had similar levels of resistance to low pH and 5 or 10% bile, suggesting that the reduced colonization of mutants was not the result of reduced resistance to acid pH or bile salts. In an in vitro lymphoepithelial cell (M-cell) model, B. melitensis transited rapidly through polarized enterocyte monolayers containing M-like cells; however, transit through monolayers containing only enterocytes was reduced or absent. These results indicate that B. melitensis is able to spread systemically from the digestive tract after infection, most likely through M cells of the mucosa-associated lymphoid tissue.Brucella spp. are facultative intracellular gram-negative bacteria that cause chronic infections in mammalian hosts. Brucella melitensis infects mainly goats and sheep, causing abortion, placentitis, and infertility, and it is considered the most pathogenic species of Brucella to humans (15). Human brucellosis is an important worldwide zoonosis that causes social and economic impacts on public health and animal production. The disease is prevalent mostly in the Middle East, Mediterranean, Central Asia, Latin America, and North Africa, with over 500,000 new cases of human brucellosis registered annually (41).Human brucellosis usually does not present with specific clinical symptoms. It is frequently associated with intermittent fever, anorexia, weakness, soreness, and inflammation affecting several organs. Spondylitis, arthritis, osteomyelitis, and epididymo-orchitis are common manifestations of the infection. However, infection of the heart and brain may also occur and can result in death (34). Human brucellosis caused by B. melitensis results mostly from ingestion of unpasteurized milk and dairy products from infected goats, sheep, camels, and cattle. The importance of food-borne infection is underlined by a recent study in Mexico, which reported that in 98% of cases, the major risk factor for brucellosis was ingestion of contaminated dairy p...

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“…RD1 is located within the ORF BMEI1651, which encodes the urease accessory protein UreE1, leading to an in-frame deletion of His149-Gly157. Most members of the genus Brucella show strong urease activity [22], and it has been suggested that urease protects Brucella during their infection via the oral route, which is the major route of infection leading to human brucellosis [22]. Blat search analysis revealed a similar RD in B. canis and B. suis 1330.…”

Section: Resultsmentioning

confidence: 99%

Genomic analysis of the original Elberg Brucella melitensis Rev.1 vaccine strain reveals insights into virulence attenuation

2018

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The live attenuated Brucella melitensis Rev.1 Elberg-originated vaccine strain has been widely used to control brucellosis in small ruminants. However, despite extensive research, the molecular mechanisms underlying the attenuation of this strain are still unknown. In the current study, we conducted a comprehensive comparative analysis of the whole-genome sequence of Rev.1 against that of the virulent reference strain, B. melitensis 16M. This analysis revealed five regions of insertion and three regions of deletion within the Rev.1 genome, among which, one large region of insertion, comprising 3,951 bp, was detected in the Rev.1 genome. In addition, we found several missense mutations within important virulence-related genes, which may be used to determine the mechanism underlying virulence attenuation. Collectively, our findings provide new insights into the Brucella virulence mechanisms and, therefore, may serve as a basis for the rational design of new Brucella vaccines.

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Characterization of the Urease Operon of Brucella abortus and Assessment of Its Role in Virulence of the Bacterium

Cited by 116 publications

References 43 publications

Functional and Phylogenetic Analysis of ureD in Shiga Toxin-Producing Escherichia coli

Functional and Phylogenetic Analysis of ureD in Shiga Toxin-Producing Escherichia coli

Establishment of Systemic Brucella melitensis Infection through the Digestive Tract Requires Urease, the Type IV Secretion System, and Lipopolysaccharide O Antigen

Genomic analysis of the original Elberg Brucella melitensis Rev.1 vaccine strain reveals insights into virulence attenuation

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