by Machulin A | Deryusheva E. | Skryabin Institute of Biochemistry and Physiology of Microorganisms,
Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of
Sciences”, Pushchino , Russia | Institute for Biological Instrumentation, Federal Research Center
“Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Pushchino,
Russia
The family of bacterial ribosomal S1 proteins (rpsA) with repetitive S1 domains differs in a
canonical sense from other similar proteins. The S1 protein is essential for cell viability
becuase it interacts with both mRNA and proteins. Protein domain repeats are known to
arise due to tandem duplications of internal genes. To study the mechanisms of repeat
expansion, we studied 1324 rpsA sequences of S1 proteins with different number of S1
domains. Analysis of rpsA showed that the gene regions encoding individual S1 domains
have no a strictly repetitive structure between groups containing different number of
domains. The part of rpsA encoding the central domains in multidomain S1 proteins is more
conserved than the terminal domains, which correlates with the fact that duplication is
found predominantly in the central region of the protein chain between other repeats. The
maximum value of rpsA identity for full-length proteins was found for S1 proteins containing
six structural domains (58%). The predominance of four- and six-domain S1 proteins can be
explained by the fact that the formation of repeating regions is based on the duplication of
several domains, while duplication of one domain is rare. The regionss of rpsA genes
encoding adjacent domains are more identical, which is consistent with the data suggesting
that duplication occurs predominantly in the middle of the protein chain between other
repeats. The regions of the gene encoding residues that form the RNA-binding site remain
conserved. All the results obtained characterize the structural features of rpsA that
determine the functioning of the S1 proteins.