Branched-Chain Amino Acids Are Required for the Survival and Virulence of<i>Actinobacillus pleuropneumoniae</i>in Swine

Subashchandrabose, Sargurunathan; LeVeque, Rhiannon M.; Wagner, Trevor; Kirkwood, Roy N.; Kiupel, Matti; Mulks, Martha H.

doi:10.1128/iai.00671-09

Cited by 23 publications

(24 citation statements)

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“…BCAA biosynthesis is critical for survival and virulence of pneumococcal pathogens. A small amount of essential BCAA exists in a healthy pig lung and A. pleuropneumoniae, a respiratory pathogen causing swine pneumonia, seems to be responsible for such a low level of BCAA [6]. The ilvI mutant of A. pleuropneumoniae inhibits growth of the pathogen in respiratory swine.…”

Section: Discussionmentioning

confidence: 99%

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Crystal Structure of IlvC, a Ketol-Acid Reductoisomerase, from Streptococcus Pneumoniae

et al. 2019

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Biosynthesis of branched-chain amino acids (BCAAs), including isoleucine, leucine and valine, is required for survival and virulence of a bacterial pathogen such as Streptococcus pneumoniae. IlvC, a ketol-acid reductoisomerase (E.C. 1.1.1.86) with NADP(H) and Mg 2+ as cofactors from the pathogenic Streptococcus pneumoniae (SpIlvC), catalyzes the second step in the BCAA biosynthetic pathway. To elucidate the structural basis for the IlvC-mediated reaction, we determined the crystal structure of SpIlvC at 1.69 Å resolution. The crystal structure of SpIlvC contains an asymmetric dimer in which one subunit is in apo-form and the other in NADP(H) and Mg 2+ -bound form. Crystallographic analysis combined with an activity assay and small-angle X-ray scattering suggested that SpIlvC retains dimeric arrangement in solution and that D83 in the NADP(H) binding site and E195 in the Mg 2+ binding site are the most critical in the catalytic activity of SpIlvC. Crystal structures of SpIlvC mutants (R49E, D83G, D191G and E195S) revealed local conformational changes only in the NADP(H) binding site. Taken together, our results establish the molecular mechanism for understanding functions of SpIlvC in pneumococcal growth and virulence.

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Section: Discussionmentioning

confidence: 99%

“…The BCAA pathways are critical for the survival and virulence of pathogenic bacteria. For instance, the BCAA biosynthetic pathway of pathogenic Actinobacillus pleuropneumoniae is involved in swine pneumonia [6]. A. pleuropneumoniae ilvI mutant showed defects in BCAA synthesis, inhibited growth and reduced virulence in swine.…”

Section: Introductionmentioning

confidence: 99%

Crystal Structure of IlvC, a Ketol-Acid Reductoisomerase, from Streptococcus Pneumoniae

et al. 2019

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“…The BCAA biosynthesis and transport system is well studied in A. pleuropneumoniae. The presence of these amino acids is required for the survival of the bacterium and their lack is responsible for the expression of both genes for their own biosynthesis, and virulence-related genes, as demonstrated in pigs (Wagner and Mulks 2006;Subashchandrabose et al 2009). GcvB is also known to regulate the PhoQ-PhoP two-component system, which is involved in magnesium homeostasis, pathogenicity, cell envelope composition, and acid resistance in several bacterial species (Coornaert et al 2013).…”

Section: Discussionmentioning

confidence: 99%

A computational strategy for the search of regulatory small RNAs in Actinobacillus pleuropneumoniae

Rossi

Bossé

et al. 2016

RNA

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Bacterial regulatory small RNAs (sRNAs) play important roles in gene regulation and are frequently connected to the expression of virulence factors in diverse bacteria. Only a few sRNAs have been described for Pasteurellaceae pathogens and no in-depth analysis of sRNAs has been described for Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, responsible for considerable losses in the swine industry. To search for sRNAs in A. pleuropneumoniae, we developed a strategy for the computational analysis of the bacterial genome by using four algorithms with different approaches, followed by experimental validation. The coding strand and expression of 17 out of 23 RNA candidates were confirmed by Northern blotting, RT-PCR, and RNA sequencing. Among them, two are likely riboswitches, three are housekeeping regulatory RNAs, two are the widely studied GcvB and 6S sRNAs, and 10 are putative novel trans-acting sRNAs, never before described for any bacteria. The latter group has several potential mRNA targets, many of which are involved with virulence, stress resistance, or metabolism, and connect the sRNAs in a complex gene regulatory network. The sRNAs identified are well conserved among the Pasteurellaceae that are evolutionarily closer to A. pleuropneumoniae and/or share the same host. Our results show that the combination of newly developed computational programs can be successfully utilized for the discovery of novel sRNAs and indicate an intricate system of gene regulation through sRNAs in A. pleuropneumoniae and in other Pasteurellaceae, thus providing clues for novel aspects of virulence that will be explored in further studies.

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“…While it has been shown that A. pleuropneumoniae produces PNAG-based biofilms, the role of biofilm in the pathobiology of porcine pleuropneumonia remains to be elucidated. It is clear that production of biofilms is not essential for experimental infection models that utilize the intratracheal route, since A. pleuropneumoniae ATCC 27088, a biofilm-negative strain, is highly virulent (6,27,53). However, it is possible that the infectious dose for a biofilm-positive strain is lower than that for an isogenic biofilm-negative strain or that biofilm formation might be critical for colonization and infection via an intranasal route of infection.…”

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confidence: 98%

“…A total of 25% (8/32) of the in vivo-induced genes, including hfq, were upregulated under limitation of the branched-chain amino acids (BCAAs) isoleucine, leucine, and valine in defined laboratory medium (5). Limitation of BCAAs is one of the host signals encountered by A. pleuropneumoniae in porcine lungs, and the ability to synthesize BCAAs is essential for the survival and virulence of A. pleuropneumoniae during experimental infection (6).…”

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confidence: 99%

The RNA Chaperone Hfq Promotes Fitness of Actinobacillus pleuropneumoniae during Porcine Pleuropneumonia

et al. 2013

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Actinobacillus pleuropneumoniae is the etiological agent of porcine pleuropneumonia, an economically important disease of pigs. The hfq gene in A. pleuropneumoniae, encoding the RNA chaperone and posttranscriptional regulator Hfq, is upregulated during infection of porcine lungs. To investigate the role of this in vivo-induced gene in A. pleuropneumoniae, an hfq mutant strain was constructed. The hfq mutant was defective in biofilm formation on abiotic surfaces. The level of pgaC transcript, encoding the biosynthesis of poly-␤-1,6-N-acetylglucosamine (PNAG), a major biofilm matrix component, was lower and PNAG content was 10-fold lower in the hfq mutant than in the wild-type strain. When outer membrane proteins were examined, cysteine synthase, implicated in resistance to oxidative stress and tellurite, was not found at detectable levels in the absence of Hfq. The hfq mutant displayed enhanced sensitivity to superoxide generated by methyl viologen and tellurite. These phenotypes were readily reversed by complementation with the hfq gene expressed from its native promoter. The role of Hfq in the fitness of A. pleuropneumoniae was assessed in a natural host infection model. The hfq mutant failed to colonize porcine lungs and was outcompeted by the wild-type strain (median competitive index of 2 ؋ 10 ؊5). Our data demonstrate that the in vivo-induced gene hfq is involved in the regulation of PNAG-dependent biofilm formation, resistance to superoxide stress, and the fitness and virulence of A. pleuropneumoniae in pigs and begin to elucidate the role of an in vivo-induced gene in the pathogenesis of pleuropneumonia.

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Branched-Chain Amino Acids Are Required for the Survival and Virulence ofActinobacillus pleuropneumoniaein Swine

Cited by 23 publications

References 64 publications

Crystal Structure of IlvC, a Ketol-Acid Reductoisomerase, from Streptococcus Pneumoniae

Crystal Structure of IlvC, a Ketol-Acid Reductoisomerase, from Streptococcus Pneumoniae

A computational strategy for the search of regulatory small RNAs in Actinobacillus pleuropneumoniae

The RNA Chaperone Hfq Promotes Fitness of Actinobacillus pleuropneumoniae during Porcine Pleuropneumonia

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