The PRC-barrel domain of the ribosome maturation protein RimM mediates binding to ribosomal protein S19 in the 30S ribosomal subunits.
The RimM protein in Escherichia coli is associated with free 30S ribosomal subunits but not with 70S ribosomes. A DeltarimM mutant is defective in 30S maturation and accumulates 17S rRNA. To study the interaction of RimM with the 30S and its involvement in 30S maturation, RimM amino acid substitution mutants were constructed. A mutant RimM (RimM-YY-->AA), containing alanine substitutions for two adjacent tyrosines within the PRC beta-barrel domain, showed a reduced binding to 30S and an accumulation of 17S rRNA compared to wild-type RimM. The (RimM-YY-->AA) and DeltarimM mutants had significantly lower amounts of polysomes and also reduced levels of 30S relative to 50S compared to a wild-type strain. A mutation in rpsS, which encodes r-protein S19, suppressed the polysome- and 16S rRNA processing deficiencies of the RimM-YY-->AA but not that of the DeltarimM mutant. A mutation in rpsM, which encodes r-protein S13, suppressed the polysome deficiency of both rimM mutants. Suppressor mutations, found in either helices 31 or 33b of 16S rRNA, improved growth of both the RimM-YY-->AA and DeltarimM mutants. However, they suppressed the 16S rRNA processing deficiency of the RimM-YY-->AA mutant more efficiently than that of the DeltarimM mutant. Helices 31 and 33b are known to interact with S13 and S19, respectively, and S13 is known to interact with S19. A GST-RimM but not a GST-RimM(YY-->AA) protein bound strongly to S19 in 30S. Thus, RimM likely facilitates maturation of the region of the head of 30S that contains S13 and S19 as well as helices 31 and 33b.
Lövgren
J Mattias
JM
Department of Molecular Biology, Umeå University, SE-90187 Umeå, Sweden.
Bylund
Göran O
GO
Srivastava
Manoj K
MK
Lundberg
L A Carina
LA
Persson
Olof P
OP
Wingsle
Gunnar
G
Wikström
P Mikael
PM
D000409:Alanine / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005982:Glutathione Transferase / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D017434:Protein Structure, Tertiary; D012323:RNA Processing, Post-Transcriptional; D012336:RNA, Ribosomal, 16S / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014443:Tyrosine / Q000378:metabolism
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D012336:RNA, Ribosomal, 16S; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D012269:Ribosomal Proteins; C436973:RimM protein, E coli; C040343:ribosomal protein S19; D014443:Tyrosine; D005982:Glutathione Transferase; D000409:Alanine