Mif

***Mif*** is a protein regulator that stops the proliferation of bacteria when conditions for reproduction become unacceptable. For example, at high temperatures. This mechanism was discovered in the 70s of the last century, and only a few years ago the first practical use of mif appeared in the form of a vaccine against tuberculosis.

MIF belongs to the family of so-called transcriptional repressors, that is, it blocks the synthesis of coregulator proteins of certain genes or stops their transcription. At the same time, it fulfills its task by “reading” directly from the DNA matrix and starting the process of “turning off” the regulatory protein products necessary for bacterial life.

The mechanism of action of mif is not implemented as a classic “switch-switch” that works like a relay. A regulator of the transcriptional activity of a particular gene “blocks” it in one way or another, but does not completely break the regulatory chain. In order for this functional “relay” to actually stop working, mif needs to be “turned on”. And in this case, the implementation of the control action is realized thanks to another factor - the operon.

Transcription repressor To understand how mif systems begin to work, let us turn to the work of the canonical operon of the bacterial genome. It consists of an operator area and a *promoter* located behind it.

A promoter is a sequence of nucleotides through which a special RNA, the leader, works. It informs the structure of RNA polymerase that this operon begins to work. Methylation of the dihydrouridine-lined site on mRNA