Dysregulation of transition metal ion homeostasis is the molecular basis for cadmium toxicity in Streptococcus pneumoniae Original paper
Researched by:
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Divine Aleru
ID
Divine Aleru
Read MoreI am a biochemist with a deep curiosity for the human microbiome and how it shapes human health, and I enjoy making microbiome science more accessible through research and writing. With 2 years experience in microbiome research, I have curated microbiome studies, analyzed microbial signatures, and now focus on interventions as a Microbiome Signatures and Interventions Research Coordinator.
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Metals
Metals
Heavy metals influence microbial pathogenicity in two ways: they can be toxic to microbes by disrupting cellular functions and inducing oxidative stress, and they can be exploited by pathogens to enhance survival, resist treatment, and evade immunity. Understanding metal–microbe interactions supports better antimicrobial and public health strategies.
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Microbes
Microbes
Microbes are microscopic organisms living in and on the human body, shaping health through digestion, vitamin production, and immune protection. When microbial balance is disrupted, disease can occur. This guide explains key microbe types—bacteria, viruses, fungi, protozoa, and archaea—plus major pathogenic and beneficial examples.
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Divine Aleru
Read More
Researched by:
-
Divine Aleru
ID
Divine Aleru
Read More
Microbiome Signatures identifies and validates condition-specific microbiome shifts and interventions to accelerate clinical translation. Our multidisciplinary team supports clinicians, researchers, and innovators in turning microbiome science into actionable medicine.
Divine Aleru
What was studied?
This study investigated how cadmium (Cd²⁺) affects the homeostasis of transition metal ions in Streptococcus pneumoniae. It focused on how Cd²⁺ competes with manganese (Mn²⁺) and zinc (Zn²⁺) for uptake and accumulation in the bacterium, leading to a disturbance in its metal ion balance and an increase in oxidative stress. Using a combination of assays, structural analyses, and growth experiments, the study revealed the mechanisms by which Cd²⁺ disrupts the bacterial metal uptake and efflux systems, particularly targeting the Psa permease responsible for manganese acquisition.
Who was studied?
The study focused on Streptococcus pneumoniae (S. pneumoniae), a Gram-positive bacterium. This organism was selected due to its reliance on a single manganese-specific uptake system, the PsaBCA permease. Researchers explored how the exposure to cadmium, a non-physiological metal ion, interferes with the bacterium’s homeostasis of essential metals like manganese and zinc. The study involved various mutant strains of S. pneumoniae to examine how different metal ion transporters and homeostatic systems contribute to the bacterium’s response to cadmium exposure.
Most important findings
The study uncovered how cadmium disrupts manganese and zinc homeostasis in Streptococcus pneumoniae. Cadmium competes with manganese for the Psa permease, significantly reducing manganese accumulation and enhancing the upregulation of the manganese efflux pathway (MntE). This disruption causes oxidative stress due to decreased manganese availability for the enzyme superoxide dismutase (SodA). Additionally, cadmium affects zinc homeostasis by triggering the upregulation of the zinc-efflux transporter CzcD, leading to a depletion of intracellular zinc. This dysregulation of both manganese and zinc disrupts the function of zinc-responsive transcriptional regulators such as AdcR and SczA, ultimately impairing the bacterium’s ability to manage oxidative stress.
Key implications
This study highlights the complex mechanisms by which cadmium disrupts metal ion homeostasis in bacteria. The findings provide insight into how environmental pollutants like cadmium can impair bacterial function by disturbing essential processes like metal ion uptake and oxidative stress management. These insights are crucial for developing new therapeutic strategies to mitigate the harmful effects of cadmium exposure, particularly in microorganisms.