scholarly journals A Variation of the Translation Attenuation Model Can Explain the Inducible Regulation of the pBC16 Tetracycline Resistance Gene in Bacillus subtilis

2006 ◽  
Vol 188 (13) ◽  
pp. 4749-4758 ◽  
Author(s):  
Patricia B. Lodato ◽  
Elizabeth J. Rogers ◽  
Paul S. Lovett
Keyword(s):  
Secondary Structure ◽  
Binding Site ◽  
Resistance Gene ◽  
Stop Codon ◽  
Constitutive Expression ◽  
Ribosome Binding Site ◽  
Leader Peptide ◽  
Coding Region ◽  
Attenuation Model ◽  
Ribosome Binding

ABSTRACT Expression of the tet resistance gene from plasmid pBC16 is induced by the antibiotic tetracycline, and induction is independent of the native promoter for the gene. The nucleotide sequence at the 5′ end of the tet mRNA (the leader region) is predicted to assume a complex secondary structure that sequesters the ribosome binding site for the tet gene. A spontaneous, constitutively expressed tet gene variant contains a mutation predicted to provide the tet gene with a nonsequestered ribosome binding site. Lastly, comparable levels of tet mRNA can be demonstrated in tetracycline-induced and uninduced cells. These results are consistent with the idea that the pBC16 tet gene is regulated by translation attenuation, a model originally proposed to explain the inducible regulation of the cat and erm genes in gram-positive bacteria. As with inducible cat and erm genes, the pBC16 tet gene is preceded by a translated leader open reading frame consisting of a consensus ribosome binding site and an ATG initiation codon, followed by 19 sense codons and a stop codon. Mutations that block translation of cat and erm leaders prevent gene expression. In contrast, we show that mutations that block translation of the tet leader result in constitutive expression. We provide evidence that translation of the tet leader peptide coding region blocks tet expression by preventing the formation of a secondary-structure complex that would, in the absence of leader translation, expose the tet ribosome binding site. Tetracycline is proposed to induce tet by blocking or slowing leader translation. The results indicate that tet regulation is a variation of the translation attenuation model.

scholarly journals Regulation of two nested proteins from gene 49 (recombination endonuclease VII) and of a lambda RexA-like protein of bacteriophage T4.

Genetics ◽  
1988 ◽  
Vol 120 (2) ◽  
pp. 329-343
Author(s):  
K A Barth ◽  
D Powell ◽  
M Trupin ◽  
G Mosig
Keyword(s):  
Binding Site ◽  
Stop Codon ◽  
Bacteriophage T4 ◽  
Strong Dependence ◽  
Ribosome Binding Site ◽  
Late Gene Expression ◽  
Ribosome Binding ◽  
Phage T4 ◽  
Shine Dalgarno Sequence ◽  
Endonuclease Vii

Abstract Phage T4 gene 49, encoding recombination endonuclease VII, specifies, by initiation from an AUG and an internal GUG codon, two in-frame overlapping peptides (of 18 and 12 kD). The gene is transcribed early and late, albeit from different promoters. The sequence predicts that in long early transcripts, initiated far upstream of the coding sequence, the Shine-Dalgarno sequence of the first ribosome binding site can be sequestered in a hairpin and/or cleaved. These processes might reduce initiation from the first AUG and facilitate initiation of the 12-kD peptide from the internal GUG. The potential of this hairpin to participate in Y structures or cruciforms suggests possible autoregulation. Shorter, more stable late transcripts initiated from a late promoter immediately upstream of the first ribosome binding site cannot form this hairpin. More efficient translation of the longer 18-kD gene 49 peptide from these late transcripts accounts for the strong dependence of endonuclease VII activity on late gene expression. An ORF downstream from gene 49 can be translated from a motA-dependent transcript that starts inside gene 49 as well as from the gene 49 transcripts. Its initiation codon overlaps the stop codon of gene 49, suggesting some coupling of translation. The deduced protein resembles, among others, the RexA protein of phage lambda. Possible implications for T4 recombination and for the interference of lambda lysogens with T4 gene 49 and rII mutants are discussed.

scholarly journals Translational Control of Tetracycline Resistance and Conjugation in the Bacteroides Conjugative Transposon CTnDOT

2005 ◽  
Vol 187 (8) ◽  
pp. 2673-2680 ◽  
Author(s):  
Yanping Wang ◽  
Ella R. Rotman ◽  
Nadja B. Shoemaker ◽  
Abigail A. Salyers
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Binding Site ◽  
Translational Control ◽  
Tetracycline Resistance ◽  
Ribosome Binding Site ◽  
Hairpin Structure ◽  
Leader Peptide ◽  
Conjugative Transposon ◽  
Ribosome Binding

ABSTRACT The tetQ-rteA-rteB operon of the Bacteroides conjugative transposon CTnDOT is responsible for tetracycline control of the excision and transfer of CTnDOT. Previous studies revealed that tetracycline control of this operon occurred at the translational level and involved a hairpin structure located within the 130-base leader sequence that lies between the promoter of tetQ and the start codon of the gene. This hairpin structure is formed by two sequences, designated Hp1 and Hp8. Hp8 contains the ribosome binding site for tetQ. Examination of the leader region sequence revealed three sequences that might encode a leader peptide. One was only 3 amino acids long. The other two were 16 amino acids long. By introducing stop codons into the peptide coding regions, we have now shown that the 3-amino-acid peptide is the one that is essential for tetracycline control. Between Hp1 and Hp8 lies an 85-bp region that contains other possible RNA hairpin structures. Deletion analysis of this intervening DNA segment has now identified a sequence, designated Hp2, which is essential for tetracycline regulation. This sequence could form a short hairpin structure with Hp1. Mutations that made the Hp1-Hp2 structure more stable caused nearly constitutively high expression of the operon. Thus, stalling of ribosomes on the 3-amino-acid leader peptide could favor formation of the Hp1-Hp2 structure and thus preclude formation of the Hp1-Hp8 structure, releasing the ribosome binding site of tetQ. Finally, comparison of the CTnDOT tetQ leader regions with upstream regions of five tetQ genes found in other elements reveals that the sequences are virtually identical, suggesting that translational attenuation is responsible for control of tetracycline resistance in these other cases as well.

scholarly journals Tandem duplication in ermC translational attenuator of the macrolide-lincosamide-streptogramin B resistance plasmid pSES6 from Staphylococcus equorum.

1996 ◽  
Vol 40 (1) ◽  
pp. 215-217 ◽  
Author(s):  
G Lodder ◽  
S Schwarz ◽  
P Gregory ◽  
K Dyke
Keyword(s):  
Binding Site ◽  
Tandem Duplication ◽  
Constitutive Expression ◽  
Ribosome Binding Site ◽  
Coding Sequence ◽  
Ribosome Binding ◽  
Constitutive Resistance ◽  
Resistance Plasmid ◽  
Staphylococcus Equorum

A tandem duplication of 23 bp in the ermC gene translational attenuator of plasmid pSES6 from Staphylococcus equorum which mediated constitutive resistance to macrolide-lincosamide-streptogramin B antibiotics was identified. This duplication included the ribosome binding site for the ermC gene as well as the first 5 bp of the ermC coding sequence. It was postulated that this sequence duplication affects the possible RNA conformations so that the ribosome binding site for ErmC synthesis is readily accessible to the ribosomes and thus constitutive expression of the ermC gene occurs.

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