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Functional analysis of an intergenic non-coding sequence within mce1 operon of M.tuberculosis

BACKGROUND: The mce operons play an important role in the entry of M. tuberculosis into macrophages and non-phagocytic cells. Their non-redundant function as well as complex regulation is implied by the phenotype of mce mutants. Recently, mce1 operon was found to extend over 13 genes, fadD5 (Rv0166)...

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Autores principales: Joon, Monika, Bhatia, Shipra, Pasricha, Rashmi, Bose, Mridula, Brahmachari, Vani
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2010
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2867952/
https://www.ncbi.nlm.nih.gov/pubmed/20420720
http://dx.doi.org/10.1186/1471-2180-10-128
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author Joon, Monika
Bhatia, Shipra
Pasricha, Rashmi
Bose, Mridula
Brahmachari, Vani
author_facet Joon, Monika
Bhatia, Shipra
Pasricha, Rashmi
Bose, Mridula
Brahmachari, Vani
author_sort Joon, Monika
collection PubMed
description BACKGROUND: The mce operons play an important role in the entry of M. tuberculosis into macrophages and non-phagocytic cells. Their non-redundant function as well as complex regulation is implied by the phenotype of mce mutants. Recently, mce1 operon was found to extend over 13 genes, fadD5 (Rv0166) being the first gene of the operon. The presence of a non-coding sequence of 200 base pairs between Rv0166 and Rv0167 is peculiar to mce1 among the four mce operons of M.tuberculosis. We have examined the function of this region. RESULTS: We predicted putative promoter activity of the 200 base pairs of non-coding, intergenic region between Rv0166 and Rv0167 in silico using MEME software and designate it as intergenic promoter, IGPr. We demonstrate both promoter activity and a putative negative regulatory function of this fragment by reporter assays carried out in the surrogate host M.smegmatis. We find that the repressive elements not only control the native promoter but also repress a heterologous promoter of M.smegmatis. The higher activity of the intergenic promoter in a clinical isolate in comparison with the wild type sequence from M.tuberculosis H37Rv could be correlated with a point mutation within the negative element. We have mapped two transcription start sites for mce1 operon both of which are utilized in M.tuberculosis H37Rv as well as the clinical isolate VPCI591. Our studies show that the promoter activity in the non-coding region is relevant not only in reporter gene expression but also in the expression of mce1 operon in M. tuberculosis cells grown in synthetic medium. CONCLUSION: The mce operon of M.tuberculosis H37Rv potentially can be transcribed from two promoters P1 and P2, former mapping upstream of Rv0166 and the latter in the non-coding intergenic region between Rv0166 and Rv0167. The transcription initiation from P1 results in a transcript with Rv0166 while that from P2 will be without it. The sequences between the translation start site of Rv0167 and the promoter P2 have a negative regulatory role, as point mutation within the sequence leads to enhanced activity of P2 as well as a heterologous promoter from M.smegmatis. The mutation detected in the clinical isolate VPCI591 therefore behaves like a gain-of-function mutation.
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spelling pubmed-28679522010-05-12 Functional analysis of an intergenic non-coding sequence within mce1 operon of M.tuberculosis Joon, Monika Bhatia, Shipra Pasricha, Rashmi Bose, Mridula Brahmachari, Vani BMC Microbiol Research article BACKGROUND: The mce operons play an important role in the entry of M. tuberculosis into macrophages and non-phagocytic cells. Their non-redundant function as well as complex regulation is implied by the phenotype of mce mutants. Recently, mce1 operon was found to extend over 13 genes, fadD5 (Rv0166) being the first gene of the operon. The presence of a non-coding sequence of 200 base pairs between Rv0166 and Rv0167 is peculiar to mce1 among the four mce operons of M.tuberculosis. We have examined the function of this region. RESULTS: We predicted putative promoter activity of the 200 base pairs of non-coding, intergenic region between Rv0166 and Rv0167 in silico using MEME software and designate it as intergenic promoter, IGPr. We demonstrate both promoter activity and a putative negative regulatory function of this fragment by reporter assays carried out in the surrogate host M.smegmatis. We find that the repressive elements not only control the native promoter but also repress a heterologous promoter of M.smegmatis. The higher activity of the intergenic promoter in a clinical isolate in comparison with the wild type sequence from M.tuberculosis H37Rv could be correlated with a point mutation within the negative element. We have mapped two transcription start sites for mce1 operon both of which are utilized in M.tuberculosis H37Rv as well as the clinical isolate VPCI591. Our studies show that the promoter activity in the non-coding region is relevant not only in reporter gene expression but also in the expression of mce1 operon in M. tuberculosis cells grown in synthetic medium. CONCLUSION: The mce operon of M.tuberculosis H37Rv potentially can be transcribed from two promoters P1 and P2, former mapping upstream of Rv0166 and the latter in the non-coding intergenic region between Rv0166 and Rv0167. The transcription initiation from P1 results in a transcript with Rv0166 while that from P2 will be without it. The sequences between the translation start site of Rv0167 and the promoter P2 have a negative regulatory role, as point mutation within the sequence leads to enhanced activity of P2 as well as a heterologous promoter from M.smegmatis. The mutation detected in the clinical isolate VPCI591 therefore behaves like a gain-of-function mutation. BioMed Central 2010-04-27 /pmc/articles/PMC2867952/ /pubmed/20420720 http://dx.doi.org/10.1186/1471-2180-10-128 Text en Copyright ©2010 Joon et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research article
Joon, Monika
Bhatia, Shipra
Pasricha, Rashmi
Bose, Mridula
Brahmachari, Vani
Functional analysis of an intergenic non-coding sequence within mce1 operon of M.tuberculosis
title Functional analysis of an intergenic non-coding sequence within mce1 operon of M.tuberculosis
title_full Functional analysis of an intergenic non-coding sequence within mce1 operon of M.tuberculosis
title_fullStr Functional analysis of an intergenic non-coding sequence within mce1 operon of M.tuberculosis
title_full_unstemmed Functional analysis of an intergenic non-coding sequence within mce1 operon of M.tuberculosis
title_short Functional analysis of an intergenic non-coding sequence within mce1 operon of M.tuberculosis
title_sort functional analysis of an intergenic non-coding sequence within mce1 operon of m.tuberculosis
topic Research article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2867952/
https://www.ncbi.nlm.nih.gov/pubmed/20420720
http://dx.doi.org/10.1186/1471-2180-10-128
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