Related Experiment Video

Updated: Jul 8, 2026

Following in Real Time the Impact of Pneumococcal Virulence Factors in an Acute Mouse Pneumonia Model Using Bioluminescent Bacteria
11:32

Following in Real Time the Impact of Pneumococcal Virulence Factors in an Acute Mouse Pneumonia Model Using Bioluminescent Bacteria

Published on: February 23, 2014

A pneumococcal MerR-like regulator and S-nitrosoglutathione reductase are required for systemic virulence

Uwe H Stroeher1, Stephen P Kidd, Sian L Stafford

  • 1Australian Bacterial Pathogenesis Program, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia.

The Journal of Infectious Diseases
|January 15, 2008
PubMed

Insights

Streptococcus pneumoniae uses NmlR and AdhC to defend against nitric oxide (NO) stress. These factors are crucial for bacterial survival in the bloodstream during infection.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Infectious Diseases

Background:

  • Streptococcus pneumoniae is a significant human pathogen.
  • Nitric oxide (NO) is a key component of the host immune response.
  • Bacterial defense mechanisms against NO are critical for pathogenesis.

Purpose of the Study:

  • To identify and characterize novel components of the nitric oxide (NO) defense system in Streptococcus pneumoniae.
  • To investigate the role of NmlR(sp) and AdhC in NO resistance and virulence.

Main Methods:

  • Gene expression analysis (cotranscription of nmlR(sp) and adhC).
  • Biochemical assays to measure NADH-GSNO oxidoreductase activity.
  • In vitro susceptibility testing against NO.
  • In vivo virulence studies using mouse models (nasopharyngeal adherence and intraperitoneal challenge).

Main Results:

  • NmlR(sp) is a transcriptional regulator involved in NO defense.
  • AdhC encodes an alcohol dehydrogenase with NADH-GSNO oxidoreductase activity.
  • Mutants lacking nmlR(sp) or adhC showed increased susceptibility to NO and reduced oxidoreductase activity.
  • NmlR(sp) and AdhC were essential for pneumococcal survival in the bloodstream but not for nasopharyngeal adherence.

Conclusions:

  • NmlR(sp) and AdhC are novel components of a Streptococcus pneumoniae nitric oxide (NO) defense system.
  • This NO defense system is critical for pneumococcal survival during systemic infection.
  • These findings provide insights into bacterial pathogenesis and host-pathogen interactions.

More Related Videos

A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues07:10

A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues

Published on: February 19, 2019

Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae09:12

Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae

Published on: January 17, 2014

Related Concept Videos

Regulation of Bacterial Virulence01:28

Regulation of Bacterial Virulence

Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...
Determinants of Bacterial Pathogenicity and Virulence01:20

Determinants of Bacterial Pathogenicity and Virulence

Pathogenic bacteria employ a variety of strategies to establish infections, including the secretion of extracellular enzymes that act as potent virulence factors. These enzymes facilitate bacterial colonization of host tissues and help evade immune surveillance. By targeting structural components of host tissues and interfering with immune mechanisms, these enzymes play a pivotal role in disease progression.Extracellular Enzymes Facilitating Tissue Invasion: Several bacterial pathogens secrete...
Gene Regulation in Microbial Communities: Quorum Sensing01:28

Gene Regulation in Microbial Communities: Quorum Sensing

Quorum sensing is a mechanism of bacterial communication that enables coordinated gene expression in response to changes in population density. This facilitates collective behaviors that enhance survival, resource acquisition, and ecological adaptation. This process relies on small signaling molecules called autoinducers that accumulate as bacterial populations grow. When a critical threshold concentration of autoinducers is reached, bacterial cells collectively modify gene expression,...
Pneumonia II: Pathophysiology01:29

Pneumonia II: Pathophysiology

The pathophysiology of pneumonia involves the following steps:
Mechanism of Antibiotic Resistance in MRSA01:25

Mechanism of Antibiotic Resistance in MRSA

Antibiotic resistance in bacteria arises when microorganisms evolve the ability to withstand drugs designed to kill them or inhibit their growth, rendering once-effective treatments useless. This phenomenon, driven by genetic change and selection under antibiotic exposure, poses a profound threat to modern medicine. Mechanisms include drug-inactivating enzymes (e.g., β-lactamases), efflux pumps that eject antibiotics, mutations altering antibiotic targets, decreased drug uptake, and acquisition...
Bacterial Meningitis II: Pathophysiology01:26

Bacterial Meningitis II: Pathophysiology

Bacterial meningitis typically begins when pathogens such as Neisseria meningitidis and Streptococcus pneumoniae colonize the nasopharynx and invade the bloodstream. This process is facilitated by bacterial virulence factors, such as polysaccharide capsules, which resist phagocytosis and complement-mediated killing. Less commonly, bacteria reach the central nervous system via contiguous spread from infections like otitis media or sinusitis, through congenital or acquired dural defects, or...