Specific recognition of rpsO mRNA and 16S rRNA by Escherichia coli ribosomal protein S15 relies on both mimicry and site differentiation.
The ribosomal protein S15 binds to 16S rRNA, during ribosome assembly, and to its own mRNA (rpsO mRNA), affecting autocontrol of its expression. In both cases, the RNA binding site is bipartite with a common subsite consisting of a G*U/G-C motif. The second subsite is located in a three-way junction in 16S rRNA and in the distal part of a stem forming a pseudoknot in Escherichia coli rpsO mRNA. To determine the extent of mimicry between these two RNA targets, we determined which amino acids interact with rpsO mRNA. A plasmid carrying rpsO (the S15 gene) was mutagenized and introduced into a strain lacking S15 and harbouring an rpsO-lacZ translational fusion. Analysis of deregulated mutants shows that each subsite of rpsO mRNA is recognized by a set of amino acids known to interact with 16S rRNA. In addition to the G*U/G-C motif, which is recognized by the same amino acids in both targets, the other subsite interacts with amino acids also involved in contacts with helix H22 of 16S rRNA, in the region adjacent to the three-way junction. However, specific S15-rpsO mRNA interactions can also be found, probably with A(-46) in loop L1 of the pseudoknot, demonstrating that mimicry between the two targets is limited.
Mathy
Nathalie
N
UPR9073 du CNRS, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France.
Pellegrini
Olivier
O
Serganov
Alexander
A
Patel
Dinshaw J
DJ
Ehresmann
Chantal
C
Portier
Claude
C
D000595:Amino Acid Sequence; D001483:Base Sequence; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008958:Models, Molecular; D018716:Molecular Mimicry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D017433:Protein Structure, Secondary; D012333:RNA, Messenger / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D016415:Sequence Alignment
D029968:Escherichia coli Proteins; D012333:RNA, Messenger; D012336:RNA, Ribosomal, 16S; D011993:Recombinant Fusion Proteins; D012269:Ribosomal Proteins; C036004:ribosomal protein S15