The Cold Shock Protein CspB from Mycobacterium tuberculosis Binds to MTS0997 sRNA and MTS1338 sRNA as a Dimer

RNA chaperones play a crucial role in the biogenesis and function of various RNAs in bacteria. They facilitate the interaction of small regulatory trans-encoded sRNAs with mRNAs, thereby significantly altering the pattern of gene expression in cells. This allows bacteria responses quickly to changing environmental conditions, such as stress or adaptation to host organisms. Despite the identification of a large number of sRNAs in mycobacteria, none of the most common RNA chaperones has been found in their genomes. We characterized the cold shock protein CspB from Mycobacterium tuberculosis as a potential RNA chaperone. It forms a dimer due to its elongated C-terminal region, which is a hairpin composed of two α-helices. We demonstrated that CspB from M. tuberculosis exhibits high affinity for the two studied sRNAs from the same organism and, unlike the single-domain CspA, could be considered as a potential RNA chaperone in mycobacteria. Thus, it may be involved in the regulation of bacterial pathogenesis via interactions with sRNAs.