Article

Identification of two small regulatory RNAs linked to virulence in Brucella abortus 2308

Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville, NC 27834, USA.
Molecular Microbiology (Impact Factor: 5.03). 06/2012; 85(2):345-60. DOI: 10.1111/j.1365-2958.2012.08117.x
Source: PubMed

ABSTRACT Hfq is an RNA-binding protein that functions in post-transcriptional gene regulation by mediating interactions between mRNAs and small regulatory RNAs (sRNAs). Two proteins encoded by BAB1_1794 and BAB2_0612 are highly over-produced in a Brucella abortus hfq mutant compared with the parental strain, and recently, expression of orthologues of these proteins in Agrobacterium tumefaciens was shown to be regulated by two sRNAs, called AbcR1 and AbcR2. Orthologous sRNAs (likewise designated AbcR1 and AbcR2) have been identified in B. abortus 2308. In Brucella, abcR1 and abcR2 single mutants are not defective in their ability to survive in cultured murine macrophages, but an abcR1 abcR2 double mutant exhibits significant attenuation in macrophages. Additionally, the abcR1 abcR2 double mutant displays significant attenuation in a mouse model of chronic Brucella infection. Quantitative proteomics and microarray analyses revealed that the AbcR sRNAs predominantly regulate genes predicted to be involved in amino acid and polyamine transport and metabolism, and Northern blot analyses indicate that the AbcR sRNAs accelerate the degradation of the target mRNAs. In an Escherichia coli two-plasmid reporter system, overexpression of either AbcR1 or AbcR2 was sufficient for regulation of target mRNAs, indicating that the AbcR sRNAs from B. abortus 2308 perform redundant regulatory functions.

Download full-text

Full-text

Available from: K. Sayood, Dec 11, 2014
1 Follower
 · 
115 Views
  • Source
    • "Small non-coding RNAs (ncRNAs) are transcripts that function in a bacterial cell structurally as RNA molecules rather than as templates for translation into polypeptides (Majdalani et al., 2005). ncRNAs play important regulatory roles in bacterial stress responses to diverse environmental signals, such as changes in temperature, osmolarity, iron and oxidative stress (Gottesman, 2005; Gottesman et al., 2006; Massé et al., 2007; Romby et al., 2006; Silvaggi et al., 2006), and have key roles in the regulation of virulence factors in a variety of pathogens (Altier et al., 2000; Caswell et al., 2012; De Lay & Gottesman, 2012; Hébrard et al., 2012; Kreikemeyer et al., 2001; Le Rhun & Charpentier, 2012; Lenz et al., 2005, 2004; Mangold et al., 2004; Sonnleitner et al., 2012), including Pseudomonas aeruginosa (Burrowes et al., 2005; Heurlier et al., 2004). A single ncRNA species can directly regulate multiple genes, leading to pleiotropic effects (Gottesman et al., 2006). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Bacteria contain small non-coding RNAs (ncRNAs) that are responsible for altering transcription, translation, or mRNA stability. ncRNAs are important because they regulate virulence factors and susceptibility to various stresses. Here, the regulation of a recently described ncRNA of Pseudomonas syringae pv. tomato DC3000, P16 was investigated. We determined that RpoS regulates the expression of P16. We found that deletion of P16 results in increased sensitivity to hydrogen peroxide compared to the wild-type strain, suggesting that P16 plays a role in the bacteria's susceptibility to oxidative stress. Additionally the P16 mutant displayed enhanced resistance to heat stress. Our findings provide new information on the regulation and role of this ncRNA in P. syringae.
    Microbiology 12/2012; 159(Pt 2). DOI:10.1099/mic.0.063826-0 · 2.84 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Hfq protein mediates gene regulation by small RNAs (sRNAs) in about 50% of all bacteria. Depending on the species, phenotypic defects of an hfq mutant range from mild to severe. Here, we document that the purified Hfq protein of the plant pathogen and natural genetic engineer Agrobacterium tumefaciens binds to the previously described sRNA AbcR1 and its target mRNA atu2422, which codes for the substrate binding protein of an ABC transporter taking up proline and γ-aminobutyric acid (GABA). Several other ABC transporter components were overproduced in an hfq mutant compared to their levels in the parental strain, suggesting that Hfq plays a major role in controlling the uptake systems and metabolic versatility of A. tumefaciens. The hfq mutant showed delayed growth, altered cell morphology, and reduced motility. Although the DNA-transferring type IV secretion system was produced, tumor formation by the mutant strain was attenuated, demonstrating an important contribution of Hfq to plant transformation by A. tumefaciens.
    Journal of bacteriology 07/2012; 194(19):5209-17. DOI:10.1128/JB.00510-12 · 2.69 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Riboregulation stands for RNA-based control of gene expression. In bacteria, small non-coding RNAs (sRNAs) are a major class of riboregulatory elements, most of which act at the post-transcriptional level by base-pairing target mRNA genes. The RNA chaperone Hfq facilitates antisense interactions between target mRNAs and regulatory sRNAs, thus influencing mRNA stability and/or translation rate. In the α-proteobacterium Sinorhizobium meliloti strain 2011, the identification and detection of multiple sRNAs genes and the broadly pleitropic phenotype associated to the absence of a functional Hfq protein both support the existence of riboregulatory circuits controlling gene expression to ensure the fitness of this bacterium in both free living and symbiotic conditions. In order to identify target mRNAs subject to Hfq-dependent riboregulation, we have compared the proteome of an hfq mutant and the wild type S. meliloti by quantitative proteomics following protein labelling with (15)N. Among 2139 univocally identified proteins, a total of 195 proteins showed a differential abundance between the Hfq mutant and the wild type strain; 65 proteins accumulated ≥2-fold whereas 130 were downregulated (≤0.5-fold) in the absence of Hfq. This profound proteomic impact implies a major role for Hfq on regulation of diverse physiological processes in S. meliloti, from transport of small molecules to homeostasis of iron and nitrogen. Changes in the cellular levels of proteins involved in transport of nucleotides, peptides and amino acids, and in iron homeostasis, were confirmed with phenotypic assays. These results represent the first quantitative proteomic analysis in S. meliloti. The comparative analysis of the hfq mutant proteome allowed identification of novel strongly Hfq-regulated genes in S. meliloti.
    PLoS ONE 10/2012; 7(10):e48494. DOI:10.1371/journal.pone.0048494 · 3.53 Impact Factor
Show more