Ribosomal protein L20 controls expression of the Bacillus subtilis infC operon via a transcription attenuation mechanism.
In contrast to Escherichia coli no molecular mechanism controlling the biosynthesis of ribosomal proteins has been elucidated in Gram-positive organisms. Here we show that the expression of the Bacillus subtilis infC-rpmI-rplT operon encoding translation factor IF3 and the ribosomal proteins L35 and L20 is autoregulated by a complex transcription attenuation mechanism. It implicates a 200-bp leader region upstream of infC which contains two conserved regulatory elements, one of which can act as a transcription terminator. Using in vitro and in vivo approaches we show that expression of the operon is regulated at the level of transcription elongation by a change in the structure of the leader mRNA which depends upon the presence of ribosomal protein L20. L20 binds to a phylogenetically conserved domain and provokes premature transcription termination at the leader terminator. Footprint and toeprint experiments support a regulatory model involving molecular mimicry between the L20-binding sites on 23S rRNA and the mRNA. Our data suggest that Nomura's model of ribosomal protein biosynthesis based on autogenous control and molecular mimicry is also valid in Gram-positive organisms.
Choonee
Nasslie
N
CNRS UPR9073, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France.
Even
Sergine
S
Zig
Lena
L
Putzer
Harald
H
D020121:5' Untranslated Regions / Q000737:chemistry; D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D017124:Conserved Sequence; D015964:Gene Expression Regulation, Bacterial; D008957:Models, Genetic; D018716:Molecular Mimicry; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009876:Operon; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000737:chemistry; D012335:RNA, Ribosomal / Q000737:chemistry; D050436:Regulatory Elements, Transcriptional; D012269:Ribosomal Proteins / Q000235:genetics* / Q000378:metabolism*; D013728:Terminator Regions, Genetic; D014158:Transcription, Genetic
D020121:5' Untranslated Regions; D001426:Bacterial Proteins; C040045:L20 ribosomal protein, bacteria; D012333:RNA, Messenger; D012335:RNA, Ribosomal; D012269:Ribosomal Proteins