Escherichia coli ribosomal protein L10 is rapidly degraded when synthesized in excess of ribosomal protein L7/L12.
In Escherichia coli the genes encoding ribosomal proteins L10 and L7/12, rplJ and rplL, respectively, are cotranscribed and subject to translational coupling. Synthesis of both proteins is coordinately regulated at the translational level by binding of L10 or a complex of L10 and L7/L12 to a single target in the mRNA leader region upstream of rplJ. Unexpectedly, small deletions that inactivated the ribosome-binding site of the rplL gene carried on multicopy plasmids exerted a negative effect on expression of the upstream rplJ gene. This effect could be overcome by overproduction of L7/L12 in trans from another plasmid. This apparent stimulation resulted from stabilization of the overproduced L10 protein by L7/L12, presumably because free L10, in contrast to L10 complexed with L7/L12, is subject to rapid proteolytic decay. The contribution of this decay mechanism to the regulation of the rplJL operon is evaluated.
Institute of Microbiology, University of Copenhagen, Denmark.
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Petersen
D001426:Bacterial Proteins / Q000096:biosynthesis*; D001483:Base Sequence; D002872:Chromosome Deletion; D004926:Escherichia coli / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009876:Operon; D000080882:Ribosomal Protein L10; D012269:Ribosomal Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*
D001426:Bacterial Proteins; D012269:Ribosomal Proteins; C016700:ribosomal protein L7-L12