Lead: pathogens within the host must have iron to reproduce. Pathogenic organism can be suppressed by controlling the content of free iron ions, to maintain the body healthy.
With us humans, the bacteria also need iron to grow. In the natural environment, although there are a lot of iron, but mostly water-insoluble minerals, bacteria have evolved the ability to obtain iron. Many bacteria can secrete a class of small molecules known as iron-carrying molecule (siderophore), which can be combined with high iron and high iron ions through the surface receptor trafficking into the bacterial cell. Many bacteria can also secrete high-speed rail reductase or reducing properties of small molecules to be converted into high-iron, ferrous ion, ferrous ferrous ions can be transferred via transporter proteins (FeoB) on the cell membrane of the cell.
Host and pathogen iron resource wars, the host iron binding by proteins, such as storage protein ferritin and transferrin, and strictly control the levels of free iron ions. So in addition to avoid damage of oxygen free radicals, you can resist the invasion of pathogens.
Another important and relevant to inhibit bacterial protein is lactoferrin (lactotransferrin). Lactoferrin is a special kind of glycosylated transferrin, widely present in milk, saliva, tears, mucus and other secretions, but also in neutrophils (neutrophil) in. Human milk lactoferrin concentration of about 1.0-3.2mg / ml, 20% of the total ordinary human milk protein. Milk lactoferrin content is relatively low, only 0.02-0.35mg / ml. By transgenic technology has successfully cultivate transgenic cows secretion of human lactoferrin. Ability to combine high iron lactoferrin has a higher transferrin, especially in an acidic environment. Lactoferrin is an important part of the human innate immune system. It is not only a lack of iron can cause pathogens to the environment, can also be incorporated in the bacterial surface using high-speed rail to bring the ion generating oxygen free radicals damage cell membranes and kill bacteria. Because the presence of milk lactoferrin can inhibit bacterial growth, so the milk can be stored at room temperature for some time without deterioration. New mother office workers can work in space to pump breast milk is good, take it home for the baby to eat.
A serious lack of iron in the body of the host environment promote pathogen evolved a way to get more iron nutrition. Some pathogens can destroy their host protease transferrin to release above the high iron for their own a number of pathogens can take advantage of the release of soluble molecules is reduced and iron storage protein in iron. Some pathogens can even directly use the heme iron. Because the host cells contain relatively more iron, some of pathogens by phagocytosis or active intrusion into the cell, parasitic obtain nutrients including iron within the cell.
In the pathogens currently found only spirochetes that cause Lyme disease are extremely rare iron contained within each cell only a few atoms of iron. For other organisms so little iron is not enough to sustain its life, it seems that does not need iron table Ming Laimu pylori can survive. But as a parasite, it needs to obtain nutrients from the host, the host is dependent on iron, so it needs iron or indirectly.
With animals, the bacteria inside the iron content is strictly regulated. Many bacteria use iron absorption regulators (Ferric uptake regulator, Fur) to regulate the absorption of iron and expression of the gene. The regulator needs to ferrous ions as a cofactor, when the cell contains more ferrous ions which are bound to the particular sequence of DNA, gene expression when some cells containing less iron, it loses Asia iron, will escape from the DNA to initiate expression of genes related to iron absorption, the bacteria get more iron.
Some organisms also use a special form of iron. The nature of the biological aerobic respiration is the final electron transfer to the oxygen molecule, derive the energy necessary for life activities. Lack of oxygen in the extreme environment, some bacteria have a special way of breathing. For example, in the lack of oxygen in the mine closed, by some bacteria secrete soluble small molecule or a conductive cell surface molecules, the electron transfer to the final mineral containing iron ions, thereby to maintain the life.
In summary, whether directly or indirectly, all life forms iron is essential nutrients. Animals must strictly control the iron content in the body of freedom, in order to avoid damage of oxygen free radicals and prevent the invasion of pathogens. In the host body, iron is scarce nutrients, pathogens and host iron resource war will go on forever.
(Author: lattices)
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