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The Miracle of Deep Sea Hydrothermal Springs: How Does the Inverse Krebs Cycle Promote the Origin of Life in Extreme Environments?
In remote deep-sea hydrothermal vents, the origin of life is still an unsolved mystery in the scientific community. As research deepens, scientists have discovered that the reverse Krebs cycle may be an important clue to understanding how early life originated in extreme environments. This information not only changes our understanding of the evolution of life, but also provides new insights into the metabolic programs of microorganisms and their impact on life systems on Earth.
The reverse Krebs cycle is a series of chemical reactions that some bacteria and archaea use to convert carbon dioxide and water into carbon compounds. Although this process is difficult, it reveals how organisms use available materials in the environment. Get resources to survive.
Basic principles of the inverse Krebs cycle
The reverse Krebs cycle can be thought of as the reverse process of the Krebs cycle. The traditional Krebs cycle mainly oxidizes carbohydrates into carbon dioxide and water, while the reverse cycle does the opposite, using carbon dioxide and water to synthesize carbon compounds. This reaction occurs in extreme environments, such as hydrothermal vents with high pressure and temperature, where certain bacteria such as Aquificota can use hydrogen, sulfide or sulfate as electron donors to promote this process.
The uniqueness of chemical reactions
Compared with the oxidative Krebs cycle, the reverse Krebs cycle has its own special enzyme system. This cycle requires three specific enzymes, namely citrate lyase, pyroenoic acid reductase and α-ketoglutarate synthase, which have significant differences in the catalytic reactions relative to their oxidative counterparts. In particular, the reduction process of pyroenoic acid requires the use of low-potential reducing agents instead of traditional NADH.
The origin of life under extreme conditions
The inverse Krebs cycle can not only provide preliminary clues to the hypothesis of life, but also plays an important role in the biochemical reaction model of the early earth. The study found that certain disordered chemical steps can proceed under mineral catalysis and photochemistry, and that metal ions such as iron help promote these reactions in acidic environments. This enlightens us that in the early earth environment that lacked modern biological enzymes, were there still other ways to promote the occurrence of biological reactions?
Scientists believe that the reverse Krebs cycle is an effective model for understanding the process of the origin of life, and many reactions may occur in the high-pressure and high-temperature environment of deep-sea hydrothermal vents.
Possible implications for the medical field
The reverse Krebs cycle is not only important in the origin of early life on earth, but recent studies have shown that it may also be related to the pathology of cancer, especially melanoma. Tumor cells alter normal metabolic pathways to adapt to their needs, and the reverse Krebs cycle may play a role in this, known today as the "Warburg effect." This means we may be able to identify and target cancer cells through these metabolic adaptations.
Utilization of the reverse Krebs cycle by microorganisms
Several microorganisms, such as Thiomicrospira denitrificans, Candidatus Arcobacter, and Chlorobaculum tepidum, have been shown to utilize the reverse Krebs cycle to convert carbon dioxide into carbon compounds. Not only does this support the hypothesis that they originated from ancient proteinaceous bacteria, it also shows that organisms using this cycle may be much more abundant than previously thought.
Conclusion
The reverse Krebs cycle provides us with a new perspective on the origin of life in extreme environments, and inspires us to explore more mysteries of cellular and microbial metabolism. In this series of studies, we can't help but wonder, are there life forms that use similar mechanisms in other corners of the universe?
