A striking new study published in the journal Cell shows details how ancient microbes that thrive in some of the world’s most extreme environments and modern-day humans have more in common than meets the eye—namely, they both respire and conserve energy using a similar molecular mechanism, one that has adapted to changing environmental conditions over billions of years:
"Nature is really good at finding molecules that work and then modifying them and using them over and over again. This is a prime example,” said Michael W.W. Adams, a UGA Distinguished Research and Georgia Power Professor who has been studying MBH for 20 years. “Knowing the structure of MBH provides us with new insights into how Complex I evolved and how it might work.”
Almost all life on Earth relies on respiration, which converts electrical energy into a usable, chemical form. MBH and Complex I are important parts of this process; however, until now, the evolutionary connection between them was unclear. MBH’s structure also illustrates a mechanism for transducing electrical energy into chemical energy that is simpler than that in Complex I.
“The determination of MBH’s structure fills in some important missing pieces that reveal how life adjusted to sweeping changes in the environment throughout the millennia,” said Huilin Li, a professor in VARI’s Center for Epigenetics and co-senior author on the study. “This solves a fundamental, longstanding mystery in biology.”
MBH is regarded as an ancient respiratory system because it was isolated from Pyrococcus furiosus, a microbe that grows best in boiling water and that for billions of years has made its home in volcanic marine vents. This inhospitable environment, with its noxious mix of gases and extreme temperatures, is akin to the atmospheric conditions present on a much younger, much more volatile planet.
Although many aspects of the two complexes are similar, Complex I boasts several extra loops that allow it to interact with more molecules than MBH, an adaptation that likely arose along with a shift in the Earth’s atmospheric makeup.
Quite amazing - a microbe that grows best in boiling water - but it describes the conditions of young Earth and is, thus, an important part of of our story. Congratulations to Adams and his research colleagues at the Van Andel Research Institute on this important new publication.