Life's biologic complexity: Automatic molecular actions (Introduction)

by David Turell , Monday, November 28, 2016, 17:50 (2917 days ago) @ David Turell

Now shown in Staph aureus in the nose, with low oxygen using nitrogen instead:

http://phys.org/news/2016-11-staph-nitric-oxide-enzyme-colonize.html

"Like many bacteria, Staphylococcus aureus makes the enzyme nitric oxide synthase. In other living things that manufacture nitric oxide, the simple molecule controls many complex biological responses. In people, for example, it mediates blood pressure, nerve signals and sexual arousal.

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"Kinkel explained that S. aureus typically grows into a thick group or biofilm. If the bacteria pack densely into a confined location, eventually most of the available oxygen will be consumed.

"This situation can arise when staph tries to take hold and multiply inside the nose. Mucus in the nose also limits the diffusion of oxygen.

"As oxygen becomes scarce, Kinkel said, the small amount of nitric oxide produced by the bacteria further restricts aerobic respiration in an effort to reduce oxygen use. This leads to the bacteria transitioning to nitrate consumption, or microaerobic respiration, to maintain energy in the low-oxygen environment.

"The researchers outlined the biochemical activities stemming from nitric oxide synthase production. These regulate the transport of electrons in the pathogen's cell membrane, and thereby maintain energy from concentration gradients across the membrane.

"'We believe that this elegant mechanism is likely to represent the original, primordial function of enzymatic nitric oxide production in nature," Fang said. The essential bacterial mechanism appears to be evolutionarily conserved in some types of cell receptor signaling in mammals.

"Also, the researchers said, in view of the many pathogenic and environmental bacteria that produce the enzyme nitric oxide synthase, and the ubiquity of low-oxygen environments in the natural world, this mechanism is likely to be a widespread bacterial response to limited oxygen."

Comment: A clear example that bacteria have many alternate pathways for metabolism. A simple recognition that oxygen availability is very low triggers the switch. No thought involved.