How zinc starves lethal bacteria to stop infection

Nov 11, 2013

(Phys.org) —Australian researchers have found that zinc can 'starve' one of the world's most deadly bacteria by preventing its uptake of an essential metal.

The finding, by infectious disease researchers at the University of Adelaide and The University of Queensland, opens the way for further work to design in the fight against Streptococcus pneumoniae.

Streptococcus pneumoniae is responsible for more than one million deaths a year, killing children, the elderly and other vulnerable people by causing pneumonia, meningitis, and other serious .

Published today in the journal Nature Chemical Biology, the researchers describe how zinc "jams shut" a protein transporter in the so that it cannot take up manganese, an essential metal that Streptococcus pneumoniae needs to be able to invade and cause disease in humans.

"It's long been known that zinc plays an important role in the body's ability to protect against bacterial infection, but this is the first time anyone has been able to show how zinc actually blocks an essential pathway causing the bacteria to starve," says project leader Dr Christopher McDevitt, Research Fellow in the University of Adelaide's Research Centre for Infectious Diseases.

"This work spans fields from chemistry and biochemistry to microbiology and immunology to see, at an atomic level of detail, how this transport protein is responsible for keeping the bacteria alive by scavenging one essential metal (manganese), but at the same time also makes the bacteria vulnerable to being killed by another metal (zinc)," says Professor Bostjan Kobe, Professor of Structural Biology at The University of Queensland.

The study reveals that the bacterial transporter (PsaBCA) uses a 'spring-hammer' mechanism to bind the metals. The difference in size between the two metals, manganese and zinc, causes the transporter to bind them in different ways. The smaller size of zinc means that when it binds to the transporter, the mechanism closes too tightly around the , causing an essential spring in the protein to unwind too far, jamming it shut and blocking the transporter from being able to take up manganese.

"Without manganese, these bacteria can easily be cleared by the immune system," says Dr McDevitt. "For the first time, we understand how these types of transporters function. With this new information we can start to design the next generation of antibacterial agents to target and block these essential transporters."

Explore further: A link between zinc transport and diabetes

More information: www.nature.com/nchembio/journa… l/nchembio.1382.html

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User comments : 7

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nik_kelly_54
1.8 / 5 (4) Nov 11, 2013
Develop novel 'antibacterial agents', by all means, but, like giving Epsom Salts (for Mg) to help relieve pre-eclampsia, why not give Zinc (Zn) supplements to help with the symptoms of pneumonia ?? Such generic mineral supplements are cheap, cheerful, almost harmless and already on pharmacy shelves, so don't require a dozen years and umpteen clinical trials to develop...
Mike_Massen
1 / 5 (5) Nov 11, 2013
Copper is far more Oligodynamic and Phytotoxic than Zinc, most on classical western diet are deficient in Copper (WHO suggest 80% in USA are below RDI) more so than Zinc. In the Chalcolithic era some 5000 or so years ago people adapted to use Copper for holding/cooking food and then for some 4750 years until steel replaced Copper cooking pots and utensils, the average intake before the cast iron era was ~50mG/Day now we would be lucky to get 250 mcg/Day some 200 times less !

What are the consequences given Copper is important for angiogenesis ?

By all means recognise Zinc in our diets but note re Copper, they are co-antagonists so both must be present in the correct proportions and the average Caucasian is well adapted to rather high Copper levels too...

And all Iron absorption is dependent on Copper based Enzymes !
kochevnik
1.7 / 5 (9) Nov 11, 2013
Copper is far more Oligodynamic and Phytotoxic than Zinc, most on classical western diet are deficient in Copper
That is dogma. Most Western countries have copper plumbing which causes copper poisoning. If a white woman has dark nipples it is caused by copper overdose. Copper is suspected in causing Alzheimer disease
On secondthoughtthinkagain
1 / 5 (4) Nov 11, 2013
And yet I have been adding zinc to wounds to prevent infection in external applications since 40 years at least.
Mike_Massen
2.3 / 5 (6) Nov 12, 2013
kochevnik barked nonsense without research
"That is dogma"
No.
Based upon several studies in USA/Europe, peer reviewed journals found
through universities, studies in health sciences.

kochevnik makes ignorant assumptions claiming
"Most Western countries have copper plumbing which causes copper poisoning."
Possible new pipes can leach a few micrograms per litre, rather quickly surfaces become passivated with mineral encrustations & biofilms.

kochevnik made a nutty claim
"If a white woman has dark nipples it is caused by copper overdose."
An overdose of copper as sustained > ~30mG/day, does not happen on typical western diet. No evidence copper collects near nipples.

kochevnik offered
"Copper is suspected in causing Alzheimer disease"
distribution is important, low copper damages:-
http://medicalxpr...ase.html

kochevnik; do quality research, be smart instead & don't bark/copy ugly net propaganda !
antialias_physorg
4.3 / 5 (3) Nov 12, 2013
I think you guys missed the point here. The point was not to show that Zinc is an antibacterial agent (that was known). The point was to show HOW it works.

It's long been known that zinc plays an important role in the body's ability to protect against bacterial infection, but this is the first time anyone has been able to show how zinc actually blocks an essential pathway causing the bacteria to starve


The upshot of this is that one can now design pharmaceuticals that similarly block the Mg uptake mechanism (using Zinc or something in its stead that binds similarly to the same transporter)
Mike_Massen
1.7 / 5 (6) Nov 12, 2013
Not missed at all mate (antialias_physorg)
Just not acknowledging the article I guess but adding extra info & needed corrections to kochevnik
Zn is a useful nutrient (up to a point) for some bacteria as suggested here:-
http://www.phys.o...led.html

Cu however, is misunderstood, bulk of Caucasians Cu levels can be high & for long periods, its far more antibacterial than Zn, low Cu for pregnant mothers may result in Autism for children as Cu is essential for angiogenesis and especially for fine capillaries.

My own experiments, took equivalent to that people would likely ingest during early parts of Chalcolithic era - ie ~30mG+/day for 3 months - no toxic effects whatsoever, all positive outcomes & seem to have lasted.
BTW: Despite taking what most doctors considered a dangerous toxic dose, blood tests showed a level of 23 on scale of 10 to 25.

Might repeat the test early next year with more stringent conditions...