PMID:14702295

Citation	Yakhnin, H, Zhang, H, Yakhnin, AV and Babitzke, P (2004) The trp RNA-binding attenuation protein of Bacillus subtilis regulates translation of the tryptophan transport gene trpP (yhaG) by blocking ribosome binding. J. Bacteriol. 186:278-86
Abstract	Expression of the Bacillus subtilis tryptophan biosynthetic genes (trpEDCFBA and pabA [trpG]) is regulated in response to tryptophan by TRAP, the trp RNA-binding attenuation protein. TRAP-mediated regulation of the tryptophan biosynthetic genes includes a transcription attenuation and two distinct translation control mechanisms. TRAP also regulates translation of trpP (yhaG), a single-gene operon that encodes a putative tryptophan transporter. Its translation initiation region contains triplet repeats typical of TRAP-regulated mRNAs. We found that regulation of trpP and pabA is unaltered in a rho mutant strain. Results from filter binding and gel mobility shift assays demonstrated that TRAP binds specifically to a segment of the trpP transcript that includes the untranslated leader and translation initiation region. While the affinities of TRAP for the trpP and pabA transcripts are similar, TRAP-mediated translation control of trpP is much more extensive than for pabA. RNA footprinting revealed that the trpP TRAP binding site consists of nine triplet repeats (five GAG, three UAG, and one AAG) that surround and overlap the trpP Shine-Dalgarno (S-D) sequence and translation start codon. Results from toeprint and RNA-directed cell-free translation experiments indicated that tryptophan-activated TRAP inhibits TrpP synthesis by preventing binding of a 30S ribosomal subunit. Taken together, our results establish that TRAP regulates translation of trpP by blocking ribosome binding. Thus, TRAP coordinately regulates tryptophan synthesis and transport by three distinct mechanisms: attenuation transcription of the trpEDCFBA operon, promoting formation of the trpE S-D blocking hairpin, and blocking ribosome binding to the pabA and trpP transcripts.
Links	PubMed PMC305772
Keywords	Amino Acid Transport Systems/genetics; Bacillus subtilis/genetics; Bacterial Proteins/genetics; Bacterial Proteins/physiology; Base Sequence; Carbon-Carbon Lyases/genetics; Escherichia coli Proteins/genetics; Molecular Sequence Data; Operon; Protein Biosynthesis; RNA, Bacterial/chemistry; RNA, Bacterial/metabolism; RNA-Binding Proteins/physiology; Ribosomes/metabolism; Transcription Factors/physiology; Trinucleotide Repeats; Tryptophan/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BACSU:MTRB		GO:0045947: negative regulation of translational initiation	ECO:0000314:		P		Figure 5. Toeprint assay showing overlapping 30S ribosome and TRAP binding sites. Figure 6. in vitro translation showing a decrease in translation of the trpP'-'gfp mRNA with increasing concentrations of TRAP.	complete CACAO 11091

References

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