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Two heme-dependent terminal oxidases power Staphylococcus aureus organ-specific colonization of the vertebrate host.

Hammer ND, Reniere ML, Cassat JE, Zhang Y, Hirsch AO, Indriati Hood M, Skaar EP - MBio (2013)

Bottom Line: Aerobic respiration is supported by heme-dependent terminal oxidases that catalyze the final step of aerobic respiration, the reduction of O2 to H2O.Systemic infection with S. aureus mutants limited to a single terminal oxidase results in an organ-specific colonization defect, resulting in reduced bacterial burdens in either the liver or the heart.This study serves to demonstrate that heme biosynthesis supports two terminal oxidases that are required for aerobic respiration and are also essential for S. aureus pathogenesis.

View Article: PubMed Central - PubMed

Affiliation: Vanderbilt University School of Medicine, Nashville, Tennessee, USA.

ABSTRACT

Unlabelled: Staphylococcus aureus is a significant cause of infections worldwide and is able to utilize aerobic respiration, anaerobic respiration, or fermentation as the means by which it generates the energy needed for proliferation. Aerobic respiration is supported by heme-dependent terminal oxidases that catalyze the final step of aerobic respiration, the reduction of O2 to H2O. An inability to respire forces bacteria to generate energy via fermentation, resulting in reduced growth. Elucidating the roles of these energy-generating pathways during colonization of the host could uncover attractive therapeutic targets. Consistent with this idea, we report that inhibiting aerobic respiration by inactivating heme biosynthesis significantly impairs the ability of S. aureus to colonize the host. Two heme-dependent terminal oxidases support aerobic respiration of S. aureus, implying that the staphylococcal respiratory chain is branched. Systemic infection with S. aureus mutants limited to a single terminal oxidase results in an organ-specific colonization defect, resulting in reduced bacterial burdens in either the liver or the heart. Finally, inhibition of aerobic respiration can be achieved by exposing S. aureus to noniron heme analogues. These data provide evidence that aerobic respiration plays a major role in S. aureus colonization of the host and that this energy-generating process is a viable therapeutic target.

Importance: Staphylococcus aureus poses a significant threat to public health as antibiotic-resistant isolates of this pathogen continue to emerge. Our understanding of the energy-generating processes that allow S. aureus to proliferate within the host is incomplete. Host-derived heme is the preferred source of nutrient iron during infection; however, S. aureus can synthesize heme de novo and use it to facilitate aerobic respiration. We demonstrate that S. aureus heme biosynthesis powers a branched aerobic respiratory chain composed of two terminal oxidases. The importance of having two terminal oxidases is demonstrated by the finding that each plays an essential role in colonizing distinct organs during systemic infection. Additionally, this process can be targeted by small-molecule heme analogues called noniron protoporphyrins. This study serves to demonstrate that heme biosynthesis supports two terminal oxidases that are required for aerobic respiration and are also essential for S. aureus pathogenesis.

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Related in: MedlinePlus

Noniron metalloporphyrins inhibit staphylococcal growth. (A) Growth of S. aureus in the presence of increasing concentrations of GaPPIX or ZnPPIX. The growth of the strains was monitored over time by measuring optical density at 600 nm. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean. (B) Aerobic (+O2) or anaerobic (−O2) growth of S. aureus in the presence of increasing concentrations of GaPPIX or ZnPPIX. Growth was monitored as the optical density at 12 h and compared to that of cells grown in the absence of the noniron PPIXs. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean. (C) S. aureus was grown in the absence or presence of 1 mM 2,2′-dipyridyl (±DIP) and 0.1 µM GaPPIX or ZnPPIX. Growth was monitored as the optical density at 12 h and compared to that of cells grown in the absence of the noniron PPIXs. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean.
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fig5: Noniron metalloporphyrins inhibit staphylococcal growth. (A) Growth of S. aureus in the presence of increasing concentrations of GaPPIX or ZnPPIX. The growth of the strains was monitored over time by measuring optical density at 600 nm. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean. (B) Aerobic (+O2) or anaerobic (−O2) growth of S. aureus in the presence of increasing concentrations of GaPPIX or ZnPPIX. Growth was monitored as the optical density at 12 h and compared to that of cells grown in the absence of the noniron PPIXs. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean. (C) S. aureus was grown in the absence or presence of 1 mM 2,2′-dipyridyl (±DIP) and 0.1 µM GaPPIX or ZnPPIX. Growth was monitored as the optical density at 12 h and compared to that of cells grown in the absence of the noniron PPIXs. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean.

Mentions: Previous reports have demonstrated that noniron metalloporphyrins inhibit the growth of many species of bacteria in iron-limited conditions (30). It has been proposed that the mechanism by which these molecules exert their antimicrobial activity is through incorporation into cytochromes, resulting in respiration arrest (30). In iron-replete conditions, S. aureus traffics heme (iron-protoporphyrin IX) to the plasma membrane (31). In similar growth conditions, increasing concentrations of either gallium protoporphyrin (GaPPIX) or zinc protoporphyrin (ZnPPIX) significantly reduces S. aureus growth and induces the SCV phenotype (Fig. 5A; see also Fig. S2). Analogous to observations in Gram-negative bacteria, GaPPIX and ZnPPIX toxicity in S. aureus is more potent in aerobic growth conditions (Fig. 5B) and when iron is depleted from the growth medium (Fig. 5C) (30). A mutant inactivated for heme transport through the iron-regulated surface determinant system (isdC) does not abrogate the toxicity of GaPPIX or ZnPPIX in iron-replete or iron-deplete growth conditions (data not shown).


Two heme-dependent terminal oxidases power Staphylococcus aureus organ-specific colonization of the vertebrate host.

Hammer ND, Reniere ML, Cassat JE, Zhang Y, Hirsch AO, Indriati Hood M, Skaar EP - MBio (2013)

Noniron metalloporphyrins inhibit staphylococcal growth. (A) Growth of S. aureus in the presence of increasing concentrations of GaPPIX or ZnPPIX. The growth of the strains was monitored over time by measuring optical density at 600 nm. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean. (B) Aerobic (+O2) or anaerobic (−O2) growth of S. aureus in the presence of increasing concentrations of GaPPIX or ZnPPIX. Growth was monitored as the optical density at 12 h and compared to that of cells grown in the absence of the noniron PPIXs. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean. (C) S. aureus was grown in the absence or presence of 1 mM 2,2′-dipyridyl (±DIP) and 0.1 µM GaPPIX or ZnPPIX. Growth was monitored as the optical density at 12 h and compared to that of cells grown in the absence of the noniron PPIXs. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3735196&req=5

fig5: Noniron metalloporphyrins inhibit staphylococcal growth. (A) Growth of S. aureus in the presence of increasing concentrations of GaPPIX or ZnPPIX. The growth of the strains was monitored over time by measuring optical density at 600 nm. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean. (B) Aerobic (+O2) or anaerobic (−O2) growth of S. aureus in the presence of increasing concentrations of GaPPIX or ZnPPIX. Growth was monitored as the optical density at 12 h and compared to that of cells grown in the absence of the noniron PPIXs. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean. (C) S. aureus was grown in the absence or presence of 1 mM 2,2′-dipyridyl (±DIP) and 0.1 µM GaPPIX or ZnPPIX. Growth was monitored as the optical density at 12 h and compared to that of cells grown in the absence of the noniron PPIXs. The average from three independent experiments is shown. Error bars represent one standard deviation from the mean.
Mentions: Previous reports have demonstrated that noniron metalloporphyrins inhibit the growth of many species of bacteria in iron-limited conditions (30). It has been proposed that the mechanism by which these molecules exert their antimicrobial activity is through incorporation into cytochromes, resulting in respiration arrest (30). In iron-replete conditions, S. aureus traffics heme (iron-protoporphyrin IX) to the plasma membrane (31). In similar growth conditions, increasing concentrations of either gallium protoporphyrin (GaPPIX) or zinc protoporphyrin (ZnPPIX) significantly reduces S. aureus growth and induces the SCV phenotype (Fig. 5A; see also Fig. S2). Analogous to observations in Gram-negative bacteria, GaPPIX and ZnPPIX toxicity in S. aureus is more potent in aerobic growth conditions (Fig. 5B) and when iron is depleted from the growth medium (Fig. 5C) (30). A mutant inactivated for heme transport through the iron-regulated surface determinant system (isdC) does not abrogate the toxicity of GaPPIX or ZnPPIX in iron-replete or iron-deplete growth conditions (data not shown).

Bottom Line: Aerobic respiration is supported by heme-dependent terminal oxidases that catalyze the final step of aerobic respiration, the reduction of O2 to H2O.Systemic infection with S. aureus mutants limited to a single terminal oxidase results in an organ-specific colonization defect, resulting in reduced bacterial burdens in either the liver or the heart.This study serves to demonstrate that heme biosynthesis supports two terminal oxidases that are required for aerobic respiration and are also essential for S. aureus pathogenesis.

View Article: PubMed Central - PubMed

Affiliation: Vanderbilt University School of Medicine, Nashville, Tennessee, USA.

ABSTRACT

Unlabelled: Staphylococcus aureus is a significant cause of infections worldwide and is able to utilize aerobic respiration, anaerobic respiration, or fermentation as the means by which it generates the energy needed for proliferation. Aerobic respiration is supported by heme-dependent terminal oxidases that catalyze the final step of aerobic respiration, the reduction of O2 to H2O. An inability to respire forces bacteria to generate energy via fermentation, resulting in reduced growth. Elucidating the roles of these energy-generating pathways during colonization of the host could uncover attractive therapeutic targets. Consistent with this idea, we report that inhibiting aerobic respiration by inactivating heme biosynthesis significantly impairs the ability of S. aureus to colonize the host. Two heme-dependent terminal oxidases support aerobic respiration of S. aureus, implying that the staphylococcal respiratory chain is branched. Systemic infection with S. aureus mutants limited to a single terminal oxidase results in an organ-specific colonization defect, resulting in reduced bacterial burdens in either the liver or the heart. Finally, inhibition of aerobic respiration can be achieved by exposing S. aureus to noniron heme analogues. These data provide evidence that aerobic respiration plays a major role in S. aureus colonization of the host and that this energy-generating process is a viable therapeutic target.

Importance: Staphylococcus aureus poses a significant threat to public health as antibiotic-resistant isolates of this pathogen continue to emerge. Our understanding of the energy-generating processes that allow S. aureus to proliferate within the host is incomplete. Host-derived heme is the preferred source of nutrient iron during infection; however, S. aureus can synthesize heme de novo and use it to facilitate aerobic respiration. We demonstrate that S. aureus heme biosynthesis powers a branched aerobic respiratory chain composed of two terminal oxidases. The importance of having two terminal oxidases is demonstrated by the finding that each plays an essential role in colonizing distinct organs during systemic infection. Additionally, this process can be targeted by small-molecule heme analogues called noniron protoporphyrins. This study serves to demonstrate that heme biosynthesis supports two terminal oxidases that are required for aerobic respiration and are also essential for S. aureus pathogenesis.

Show MeSH
Related in: MedlinePlus