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The Lactobacillus acidophilus S-layer protein gene expression site comprises two consensus promoter sequences, one of which directs transcription of stable mRNA

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Author: Boot, H.J. · Kolen, C.P.A.M. · Andreadaki, F.J. · Leer, R.J. · Pouwels, P.H.
Institution: Prins Maurits Laboratorium TNO
Source:Journal of Bacteriology, 18, 178, 5388-5394
Identifier: 233470
Keywords: Biology · Bacterial virulence · Epithelium cell · Gene expression regulation · Genetic analysis · Genetic recombination · Nonhuman · Priority journal · Promoter region · Protein secondary structure · Protein stability · Ribosome subunit · Rna sequence · Rna transcription · Bacterial Outer Membrane Proteins · Bacterial Proteins · Base Sequence · Cell Wall · Consensus Sequence · Gene Expression · Gene Expression Regulation, Bacterial · Lactobacillus acidophilus · Lactobacillus casei · Membrane Glycoproteins · Membrane Proteins · Molecular Sequence Data · Nucleic Acid Conformation · Promoter Regions (Genetics) · Recombination, Genetic · RNA, Bacterial · RNA, Messenger · Species Specificity · Transcription, Genetic · Bacteria (microorganisms)


S-proteins are proteins which form a regular structure (S-layer) on the outside of the cell walls of many bacteria. Two S-protein-encoding genes are located in opposite directions on a 6.0-kb segment of the chromosome of Lactobacillus acidophilus ATCC 4356 bacteria. Inversion of this chromosomal segment occurs through recombination between two regions with identical sequences, thereby interchanging the expressed and the silent genes. In this study, we show that the region involved in recombination also has a function in efficient S-protein production. Two promoter sequences are present in the S-protein gene expression site, although only the most downstream promoter (P-1) is used to direct mRNA synthesis. S-protein mRNA directed by this promoter has a half-life of 15 min. Its untranslated leader can form a stable secondary structure in which the 5' end is base paired, whereas the ribosome- binding site is exposed. Truncation of this leader sequence results in a reduction in protein production, as shown by reporter gene analysis of Lactobacillus casei. The results obtained indicate that the untranslated leader sequence of S-protein mRNA is involved in efficient S-protein production.