Cytokinins Cannot Be Associated with Plants Only: Being Present in Bacteria, They Also Affect Resistance to TB
Production of phytohormones called cytokinins determines how infectious is the bacteria causing tuberculosis. Illustration: Ota Blahoušek
A quite noteworthy discovery has been made by an international team of scientists whose members included Miroslav Strnad and Ondřej Novák from the Laboratory of Growth Stimulators and the Centre of the Haná Region for Biotechnological and Agricultural Research. They have found that cytokinins, currently known as plant hormones, have a much more significant role than had been assumed. Surprisingly enough, one of the genes responsible for their metabolism determines whether tuberculosis is infectious. Their work has been recently published by the renowned journal Molecular Cell.
“In the field of mycobacterial infections, it has been some time since such a revealing study. It’s important for understanding the mechanism how the bacteria causing tuberculosis are so resistant and capable of penetrating the barriers of the immune system,” said Miroslav Strnad, Head of the Laboratory of Growth Stimulators, a joint facility of the Faculty of Science, Palacký University and the Institute of Experimental Botany, Academy of Sciences of the Czech Republic.
The study was initiated by American biochemists and medical researchers who have been studying Mycobacterium tuberculosis for several years. To their surprise, they have found that these bacteria also contain a gene for cytokinins, called the “Lonely Guy” (the LOG gene in short). This means a major breakthrough, because until now, cytokinins have been associated particularly with plants. Olomouc scientists, due to their outstanding global reputation in cytokinin research, became part of the international research team.
Cytokinins have more functions
“This article reveals for the first time that cytokinins are not, in their essence, mere signal substances present exclusively in plants, but they also have a significant role in the animal and bacterial world, with considerably more functions than ever supposed,” said Ondřej Novák. Mycobacterium tuberculosis is able to penetrate the defence wall of macrophages, a type of cell that plays a critical role in innate immunity. Macrophages use nitric oxide (NO) against the unwanted intruders; however, tuberculosis bacteria can overcome even this obstacle. It has not been known why this is so until now. Scientists have recently discovered that it is the cytokinin gene that has a key role in the process, since it intensifies the effect of NO, damaging the tuberculosis bacteria.
“This information may be of import for medicine as well as other disciplines. It is a discovery of one essential mechanism – that bacteria use cytokinins in interaction with other organisms. It’s turned out that the LOG gene is present in a number of other bacteria. And since cytokinins seem to play such a role in the development of tuberculosis, it is an important finding in terms of, for example, development of new tuberculostatic therapy on the basis of cytokinins,” explained Strnad.
Top experts in cytokinin research
The co-authorship of the article in Molecular Cell is another proof of the fact that Olomouc scientists are among the world’s leading experts in cytokinin research. In 2014, their findings were published in Nature Chemical Biology, in an article describing the discovery of cytokinin transporters in plants. Another article was published in Science. “All three studies represent an important contribution to the understanding of how cytokinins function at the molecular level. I’ve been studying these substances for thirty years, and as it turns out, it was a very good decision,” said Strnad, who has also been long active in the research of anti-tumour agents derived from cytokinins. Throughout the years, his Laboratory of Growth Stimulators has gradually developed enzymes such as Olomoucine, Bohemine, and Roskovitine, used in cancer treatment.
