Přehled o publikaci

Under stress conditions in bacterial cells, the formation of a hibernating ribosome dimer (termed 100S), is a useful adaptation mechanism, which results in suppression of protein synthesis in the stationary phase. In E. coli, two protein factors, RMF and HPF, are involved in regulation of dimerization of the 70S ribosome. RMF directly participates in dimerization of 70S ribosomes and HPF stabilizes the 100S ribosomes. However, homologous proteins of RMF and HPF have not been found in archaea. Therefore, further investigations of the molecular mechanisms of ribosome hibernation in archaea are required. Here, we present a single particle cryo-EM study, revealing a novel ribosome dimerization factor (RDF) in archea. The RDF is highly specific to archeal ribosomes and is capable to interact only with archeal 30S small ribosomal subunit. In order to determine the structure of the novel RDF new approaches of de novo model building were used in combination with artificial intelligence (AI). The overall architecture of the 30S-30S dimer shows a head to body orientation. The RDF links the head and body regions of two distinct 30S molecules in the form of a dimer. The binding position of the RDF monomeric structure on the head of 30S subunit implies a mechanistic role to regulate the mRNA binding on the 30S subunit. In turn, the 30S subunits are unable to initiate the translation and stay in a hibernation mode.