Bacteria Adaptation Mechanisms to Stress Conditions with Small Non-Coding RNAs Participation

Abstract

Despite the fact that most of the bacterial genome encodes certain protein molecules, with the development of transcriptomic technologies, many genes have been discovered that transcribe RNA which is not translated into proteins. Such RNAs are called non-coding RNAs (ncRNAs). The study of only a small number of them shows that ncRNAs often act as regulatory molecules in various cellular processes: maintenance of cell wall homeostasis, protection against pathogens, virulence, etc. A special place among them is occupied by the so-called small ncRNAs with a length of ~50–300 nucleotide residues. In most cases, they form duplexes with the mRNA of certain genes, which affects the expression of the latter. However, some ncRNAs are able to directly bind to the target protein. Similar mechanisms of action of small ncRNAs give them some advantages in regulating various cellular processes compared to protein regulatory molecules. For example, when responding to an external or internal signal through small ncRNAs, the cell will need to spend less time and resources due to the absence of the translation stage. Moreover, some ncRNAs have no complete complementarity to their target RNAs, which makes the regulation more flexible, as it allows ncRNAs to participate in the response simultaneously to various cellular signals. In this review, we considered the general mechanisms by which various small ncRNAs allow bacteria to adapt to certain stressful conditions, as well as specific examples of their action in various prokaryotic organisms.