Extraribosomal functions of bacterial ribosomal proteins

Ribosomal proteins (r-proteins) constitute a considerable part of the cell proteome. Although their primary role in the cell is to serve as integral components of protein synthesis machinery, ribosomes, many of them have functions beyond the ribosome (the phenomenon known as moonlighting), acting either as individual regulatory proteins or in complexes with other cell components. Extraribosomal activities of some ribosomal proteins were observed as early as the 1970s–1980s. In recent years, both the list of moonlighting r-proteins and the repertoire of their additional functions beyond the ribosome was greatly expanded, mainly owing to new techniques developed for dissecting RNA/DNA-protein or protein-protein interactions within functional complexes involved in various cell processes. The review surveys information on the extraribosomal functions demonstrated experimentally or presumed for bacterial r-proteins.