Bacteria have complex enzyme as early as 3.4 billion years ago

A study recently published in the journal Cell Biology Chemistry reveals that 3.4 billion years ago, the ancestors of all bacteria may have enzyme complex, which is only 600 million years later than the origin of life on Earth. This discovery is amazing because scientists used to conclude that the bacteria didn't evolve until much later even 1 billion years after the origin of life. There are also other studies on expressions of recombinant mouse proteins.

Modern enzyme and molecules which they interact with are in correspondence like a lock and key. They usually only "work" for one reaction, but they can get the job done very well. Instead, Michael Harms from the University of Oregon of the United States said that earlier enzymes are "very sloppy" and don't have a relationship of lock and key with the molecules. There are many "pocket" in their structure which can seize a variety of different chemical substances and control many reactions, but none of the tasks can be well executed.

In order to study when modern enzyme appeared, Reinhard Sterner and colleagues from the University of Regensburg, Germany rebuilt a kind of enzyme consists of 4 parts in accordance with the appearance they may seem prior to isolation of modern bacteria and archaea bacteria. This enzyme called tryptophan synthase, aided the generation of a kind of amino acids which are essential to bacteria, archaea, plants and fungi. First, before importing the sequence into the computer program which finds similarities among them, the researchers analyzed the genes that encode this enzyme in modern bacteria and archaea. They then conducted thousands of simulations on the possible appearance of ancient DNA sequence which generated modern genes.

Based on the way that major bacterial populations separated from each other, the program locks one of the most-likely sequences. The team members inserted this "redivious" gene into modern E. coli cells. The gene can copy a large number of genes which were much like the modern version of enzymes. Harms said that this indicates that the time when the bacteria lost their "sloppy" protein was much earlier than people had expected. Meanwhile, DNA residue from billions of years ago does not exist, so this rebuilding experimental study is the only way to study ancient genes. Researchers also can produce some recombinant rat proteins to simulate the process.

However, Mathieu Groussin from the Massachusetts Institute of Technology thought that if researchers can reconstruct some of the other possible protein rather than the most-likely proteins, they would have more confidence in their results. In this case, they will know whether other possible sequences also had a functional protein. More kinds of recombinant proteins such as recombinant CDH12 can be found at Cusabio’s website.