Almost all organisms, from bacteria to human beings, share the same genetic code, a group of universal instructions used to convert DNA or RNA sequences into proteins, the "building blocks" of life.
Identification of the evolutionary differences between the system for the translation of the genetic code in humans and other organisms, such as bacteria in this case, are useful, for example, for the design of new antibiotics. Researchers at the Institute for Research in Biomedicine (IRB Barcelona) have discovered that an essential molecular process, namely the determination of the start of protein synthesis, until now considered to be the same for all living organisms, differs in the bacteria Mycoplasma penetrans, a human pathogen that affects the respiratory tract. M. penetrans affects immuno-depressed patients, such as those infected by the HIV virus and some cancer patients. The results of this study have been published in the latest issue of Molecular Cell.
The leader of the study, Lluís Ribas de Pouplana, researcher at IRB Barcelona and head of the Gene Translation Laboratory, explains, “our work strengthens the theory that many of the components of the initial genetic code, established 3,500 million years ago, have matured separately between distinct branches of evolution: bacteria, archaea and eukaryotes”. The origin of the genetic code is one of the issues in evolution biology in which most questions remain unanswered. “The translation machinery is so complex, so universal and so essential that it is difficult to imagine how it arose and how it has evolved. Thanks to these discoveries, we can observe that the genetic code and the protein translation system are not as universal as once thought and that some of the key components of the translation system appeared much later”, concludes Ribas.
In fact, what these researchers have discovered is a difference in the mechanism used by bacteria to differentiate between methionine and isoluecine, two essential amino acids for protein formation. Specifically, methionine is the amino acid used universally to initiate protein formation.