Arginine-Dependent Gene Regulation via the ArgR Repressor Is Species Specific in<i>Chlamydia</i>

Schaumburg, Chris S.; Tan, Ming

doi:10.1128/jb.188.3.919-927.2006

Cited by 24 publications

(26 citation statements)

References 39 publications

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“…An ABC transporter complex that is regulated in some species by an arginine-responsive transcriptional repressor probably performs this function (41). Surprisingly, cultures of C. pneumoniae and C. trachomatis grown in HEp-2 epithelial cells in the presence of 10 mM arginine had 90%-and 40%-lower progeny infectivity than cultures grown in cells in control medium (1).…”

Section: Discussionmentioning

confidence: 97%

Characterization of an Acid-Dependent Arginine Decarboxylase Enzyme from Chlamydophila pneumoniae

Giles

Graham

2007

J Bacteriol

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Genome sequences from members of the Chlamydiales encode diverged homologs of a pyruvoyl-dependent arginine decarboxylase enzyme that nonpathogenic euryarchaea use in polyamine biosynthesis. The Chlamydiales lack subsequent genes required for polyamine biosynthesis and probably obtain polyamines from their host cells. To identify the function of this protein, the CPn1032 homolog from the respiratory pathogen Chlamydophila pneumoniae was heterologously expressed and purified. This protein self-cleaved to form a reactive pyruvoyl group, and the subunits assembled into a thermostable (␣␤) 3 complex. The mature enzyme specifically catalyzed the decarboxylation of L-arginine, with an unusually low pH optimum of 3.4. The CPn1032 gene complemented a mutation in the Escherichia coli adiA gene, which encodes a pyridoxal 5-phosphate-dependent arginine decarboxylase, restoring arginine-dependent acid resistance. Acting together with a putative arginine-agmatine antiporter, the CPn1032 homologs may have evolved convergently to form an arginine-dependent acid resistance system. These genes are the first evidence that obligately intracellular chlamydiae may encounter acidic conditions. Alternatively, this system could reduce the host cell arginine concentration and produce inhibitors of nitric oxide synthase.

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Section: Discussionmentioning

confidence: 97%

Characterization of an Acid-Dependent Arginine Decarboxylase Enzyme from Chlamydophila pneumoniae

Giles

Graham

2007

J Bacteriol

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“…Subsequent steps of arginine biosynthesis can be accomplished (100), and the genes required for the conversion of ornithine to arginine, argFGH, are divergent from argR (lpg0490) in a region that also includes a putative ABC transporter (lpg0491-lpg0496). In E. coli and P. aeruginosa, ArgR regulates the expression of a number of transporters required for the uptake of amino acids and other compounds (13,60), and ArgR has been predicted to regulate arginine uptake from the host cell in some members of the Chlamydiaceae (88). It is intriguing to speculate that ArgR regulates one or more L. pneumophila transporters required for the acquisition of critical nutrients from the host cell.…”

Section: Discussionmentioning

confidence: 99%

σ^SControls Multiple Pathways Associated with Intracellular Multiplication ofLegionella pneumophila

et al. 2009

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Legionella pneumophila is the causative agent of the severe and potentially fatal pneumonia Legionnaires' disease. L. pneumophila is able to replicate within macrophages and protozoa by establishing a replicative compartment in a process that requires the Icm/Dot type IVB secretion system. The signals and regulatory pathways required for Legionella infection and intracellular replication are poorly understood. Mutation of the rpoS gene, which encodes S , does not affect growth in rich medium but severely decreases L. pneumophila intracellular multiplication within protozoan hosts. To gain insight into the intracellular multiplication defect of an rpoS mutant, we examined its pattern of gene expression during exponential and postexponential growth. We found that S affects distinct groups of genes that contribute to Legionella intracellular multiplication. We demonstrate that rpoS mutants have a functional Icm/Dot system yet are defective for the expression of many genes encoding Icm/Dot-translocated substrates. We also show that S affects the transcription of the cpxR and pmrA genes, which encode two-component response regulators that directly affect the transcription of Icm/Dot substrates. Our characterization of the L. pneumophila small RNA csrB homologs, rsmY and rsmZ, introduces a link between S and the posttranscriptional regulator CsrA. We analyzed the network of S -controlled genes by mutational analysis of transcriptional regulators affected by S . One of these, encoding the L. pneumophila arginine repressor homolog gene, argR, is required for maximal intracellular growth in amoebae. These data show that S is a key regulator of multiple pathways required for L. pneumophila intracellular multiplication.Legionella pneumophila is a gram-negative opportunistic human pathogen that causes the severe and potentially fatal pneumonia Legionnaires' disease (30,47,67,83). L. pneumophila's ability to replicate within human alveolar macrophages is essential for its capacity to cause disease (44-46). Transmission of L. pneumophila to the human lung occurs as a result of the inhalation of aerosolized contaminated water droplets (74), often from exposure to showers or whirlpool baths (96). Legionella species are ubiquitous in most naturally occurring and man-made aquatic systems, where the organism replicates within a variety of unicellular protozoan hosts (28,38,96). It has been suggested that the interaction of Legionella species with environmental protozoa has selected for the bacterium's evolutionary adaptation to intracellular life in mammalian cells (99).Intracellular multiplication of L. pneumophila requires a series of ordered events that disrupt normal endocytic trafficking in both macrophage and protozoan host cells. These include preventing phagolysosome fusion and the acidification of the Legionella-containing vacuole (LCV), followed by the acquisition of membrane material derived from the Golgi and endoplasmic reticulum compartments of the host (71,85,93,95). These events are dependent upon the Icm/Dot type ...

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“…In C. pneumoniae, the ArgR repressor regulates transcription of an operon encoding a putative ABC-type arginine transporter (46). Therefore, the arginine utilization system described here should not be required for protein synthesis.…”

Section: Discussionmentioning

confidence: 99%

Outer and Inner Membrane Proteins Compose an Arginine-Agmatine Exchange System inChlamydophila pneumoniae

Smith

Graham

2008

J Bacteriol

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Most chlamydial strains have a pyruvoyl-dependent decarboxylase protein that converts L-arginine to agmatine. However, chlamydiae do not produce arginine, so they must import it from their host. Chlamydophila pneumoniae has a gene cluster encoding a putative outer membrane porin (CPn1033 or aaxA), an arginine decarboxylase (CPn1032 or aaxB), and a putative cytoplasmic membrane transporter (CPn1031 or aaxC). The aaxC gene was expressed in Escherichia coli producing an integral cytoplasmic membrane protein that catalyzed the exchange of L-arginine for agmatine. Expression of the aaxA gene produced an outer membrane protein that enhanced the arginine uptake and decarboxylation activity of cells coexpressing aaxB and aaxC. This chlamydial arginine/agmatine exchange system complemented an E. coli mutant missing the native arginine-dependent acid resistance system. These cells survived extreme acid shock in the presence of Larginine. Biochemical and evolutionary analysis showed the aaxABC genes evolved convergently with the enteric arginine degradation system, and they could have a different physiological role in chlamydial cells. The chlamydial system uniquely includes an outer membrane porin, and it is most active at a higher pH from 3 to 5. The chlamydial AaxC transporter was resistant to cadaverine, L-lysine and L-ornithine, which inhibit the E. coli AdiC antiporter.

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Arginine-Dependent Gene Regulation via the ArgR Repressor Is Species Specific inChlamydia

Cited by 24 publications

References 39 publications

Characterization of an Acid-Dependent Arginine Decarboxylase Enzyme from Chlamydophila pneumoniae

Characterization of an Acid-Dependent Arginine Decarboxylase Enzyme from Chlamydophila pneumoniae

σ^SControls Multiple Pathways Associated with Intracellular Multiplication ofLegionella pneumophila

Outer and Inner Membrane Proteins Compose an Arginine-Agmatine Exchange System inChlamydophila pneumoniae

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Arginine-Dependent Gene Regulation via the ArgR Repressor Is Species Specific inChlamydia

Cited by 24 publications

References 39 publications

Characterization of an Acid-Dependent Arginine Decarboxylase Enzyme from Chlamydophila pneumoniae

Characterization of an Acid-Dependent Arginine Decarboxylase Enzyme from Chlamydophila pneumoniae

σSControls Multiple Pathways Associated with Intracellular Multiplication ofLegionella pneumophila

Outer and Inner Membrane Proteins Compose an Arginine-Agmatine Exchange System inChlamydophila pneumoniae

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σ^SControls Multiple Pathways Associated with Intracellular Multiplication ofLegionella pneumophila