Biological complexity: bacteria fix iron from soil (Introduction)

by David Turell , Tuesday, September 17, 2019, 17:23 (1894 days ago) @ David Turell
edited by David Turell, Tuesday, September 17, 2019, 17:43

Iron is vital to life in small amounts:

https://phys.org/news/2019-09-nitrogen-fixing-bacteria-iron.html

"Virtually all life forms require iron to survive, yet too much of the metal can be catastrophic. In healthy cells, many systems regulate this delicate balance.

"In many nitrogen-fixing bacteria, a protein called RirA plays a key role in regulating iron. It senses high levels of the metal and helps to shut down the production of proteins that bring in more iron.

"RirA contains a cluster of four iron and four sulfur atoms, which acts as a sensor for iron availability. But until now, exactly how this cluster structure detects iron levels in a cell was unclear

"The results revealed a 'loose' iron atom in the cluster. When iron levels drop, this atom is rapidly lost as it is scavenged for use in other essential cellular processes.

"Without it, the cluster in RirA collapses and the protein becomes inactive, which prompts the cell to produce proteins that enable the cell to take up iron from its surroundings.

"Once iron levels are sufficient again, RirA regains its cluster and becomes active again, stopping the production of proteins that bring in more iron.

"Iron-sulfur clusters are common in many proteins, and this work offers new insight into their various roles. It also highlights the potential to use time-resolved mass spectrometry to examine biological processes in depth.

"Prof Le Brun said 'This research provides unprecedented detail of how the iron-sensing cluster of RirA responds to low iron conditions, and establishes, for the first time, how an iron-sulfur cluster can be used to sense iron.

"'This is an important piece in the bigger puzzle of how life deals with iron, a nutrient it cannot do without but one it must also avoid having in excess.'"

Comment: This requires a special protein complex for life to use iron. Required as life began and must have been designed from the beginning. Controlling iron levels cannot be developed by hunt and peck chance. Once again this shows why bacteria are still around, having started life to now fixing the needed chemicals in the soil, and are absolutely necessary.