Inositol monophosphate phosphatase genes of <it>Mycobacterium tuberculosis</it>
<p>Abstract</p> <p>Background</p> <p>Mycobacteria use inositol in phosphatidylinositol, for anchoring lipoarabinomannan (LAM), lipomannan (LM) and phosphatidylinosotol mannosides (PIMs) in the cell envelope, and for the production of mycothiol, which maintains the redox...
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BMC
2010-02-01
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| Series: | BMC Microbiology |
| Online Access: | http://www.biomedcentral.com/1471-2180/10/50 |
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| author | Parish Tanya Av-Gay Yossef Dinadayala Premkumar Wheeler Paul R Movahedzadeh Farahnaz Daffé Mamadou Stoker Neil G |
| author_facet | Parish Tanya Av-Gay Yossef Dinadayala Premkumar Wheeler Paul R Movahedzadeh Farahnaz Daffé Mamadou Stoker Neil G |
| author_sort | Parish Tanya |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Mycobacteria use inositol in phosphatidylinositol, for anchoring lipoarabinomannan (LAM), lipomannan (LM) and phosphatidylinosotol mannosides (PIMs) in the cell envelope, and for the production of mycothiol, which maintains the redox balance of the cell. Inositol is synthesized by conversion of glucose-6-phosphate to inositol-1-phosphate, followed by dephosphorylation by inositol monophosphate phosphatases (IMPases) to form <it>myo</it>-inositol. To gain insight into how <it>Mycobacterium tuberculosis </it>synthesises inositol we carried out genetic analysis of the four IMPase homologues that are present in the <it>Mycobacterium tuberculosis </it>genome.</p> <p>Results</p> <p>Mutants lacking either <it>impA </it>(<it>Rv1604</it>) or <it>suhB </it>(<it>Rv2701c</it>) were isolated in the absence of exogenous inositol, and no differences in levels of PIMs, LM, LAM or mycothiol were observed. Mutagenesis of <it>cysQ (Rv2131c) </it>was initially unsuccessful, but was possible when a porin-like gene of <it>Mycobacterium smegmatis </it>was expressed, and also by gene switching in the merodiploid strain. In contrast, we could only obtain mutations in <it>impC </it>(<it>Rv3137</it>) when a second functional copy was provided in <it>trans</it>, even when exogenous inositol was provided. Experiments to obtain a mutant in the presence of a second copy of <it>impC </it>containing an active-site mutation, in the presence of porin-like gene of <it>M. smegmatis</it>, or in the absence of inositol 1-phosphate synthase activity, were also unsuccessful. We showed that all four genes are expressed, although at different levels, and levels of inositol phosphatase activity did not fall significantly in any of the mutants obtained.</p> <p>Conclusions</p> <p>We have shown that neither <it>impA, suhB </it>nor <it>cysQ </it>is solely responsible for inositol synthesis. In contrast, we show that <it>impC </it>is essential for mycobacterial growth under the conditions we used, and suggest it may be required in the early stages of mycothiol synthesis.</p> |
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| institution | Directory Open Access Journal |
| issn | 1471-2180 |
| language | English |
| last_indexed | 2024-12-17T12:41:16Z |
| publishDate | 2010-02-01 |
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| spelling | doaj.art-66d7f536fd444c74ba9b61bda9fc53d52022-12-21T21:48:00ZengBMCBMC Microbiology1471-21802010-02-011015010.1186/1471-2180-10-50Inositol monophosphate phosphatase genes of <it>Mycobacterium tuberculosis</it>Parish TanyaAv-Gay YossefDinadayala PremkumarWheeler Paul RMovahedzadeh FarahnazDaffé MamadouStoker Neil G<p>Abstract</p> <p>Background</p> <p>Mycobacteria use inositol in phosphatidylinositol, for anchoring lipoarabinomannan (LAM), lipomannan (LM) and phosphatidylinosotol mannosides (PIMs) in the cell envelope, and for the production of mycothiol, which maintains the redox balance of the cell. Inositol is synthesized by conversion of glucose-6-phosphate to inositol-1-phosphate, followed by dephosphorylation by inositol monophosphate phosphatases (IMPases) to form <it>myo</it>-inositol. To gain insight into how <it>Mycobacterium tuberculosis </it>synthesises inositol we carried out genetic analysis of the four IMPase homologues that are present in the <it>Mycobacterium tuberculosis </it>genome.</p> <p>Results</p> <p>Mutants lacking either <it>impA </it>(<it>Rv1604</it>) or <it>suhB </it>(<it>Rv2701c</it>) were isolated in the absence of exogenous inositol, and no differences in levels of PIMs, LM, LAM or mycothiol were observed. Mutagenesis of <it>cysQ (Rv2131c) </it>was initially unsuccessful, but was possible when a porin-like gene of <it>Mycobacterium smegmatis </it>was expressed, and also by gene switching in the merodiploid strain. In contrast, we could only obtain mutations in <it>impC </it>(<it>Rv3137</it>) when a second functional copy was provided in <it>trans</it>, even when exogenous inositol was provided. Experiments to obtain a mutant in the presence of a second copy of <it>impC </it>containing an active-site mutation, in the presence of porin-like gene of <it>M. smegmatis</it>, or in the absence of inositol 1-phosphate synthase activity, were also unsuccessful. We showed that all four genes are expressed, although at different levels, and levels of inositol phosphatase activity did not fall significantly in any of the mutants obtained.</p> <p>Conclusions</p> <p>We have shown that neither <it>impA, suhB </it>nor <it>cysQ </it>is solely responsible for inositol synthesis. In contrast, we show that <it>impC </it>is essential for mycobacterial growth under the conditions we used, and suggest it may be required in the early stages of mycothiol synthesis.</p>http://www.biomedcentral.com/1471-2180/10/50 |
| spellingShingle | Parish Tanya Av-Gay Yossef Dinadayala Premkumar Wheeler Paul R Movahedzadeh Farahnaz Daffé Mamadou Stoker Neil G Inositol monophosphate phosphatase genes of <it>Mycobacterium tuberculosis</it> BMC Microbiology |
| title | Inositol monophosphate phosphatase genes of <it>Mycobacterium tuberculosis</it> |
| title_full | Inositol monophosphate phosphatase genes of <it>Mycobacterium tuberculosis</it> |
| title_fullStr | Inositol monophosphate phosphatase genes of <it>Mycobacterium tuberculosis</it> |
| title_full_unstemmed | Inositol monophosphate phosphatase genes of <it>Mycobacterium tuberculosis</it> |
| title_short | Inositol monophosphate phosphatase genes of <it>Mycobacterium tuberculosis</it> |
| title_sort | inositol monophosphate phosphatase genes of it mycobacterium tuberculosis it |
| url | http://www.biomedcentral.com/1471-2180/10/50 |
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