Mutations in pimE restore lipoarabinomannan synthesis and growth in a Mycobacterium smegmatis lpqW mutant

Paul Crellin, Svetozar Kovacevic, Kirstee L Martin, Rajini Brammananth, Yasu S Morita, Helen Billman-Jacobe, Malcolm J McConville, Ross Leon Coppel

Research output: Contribution to journalArticleResearchpeer-review

24 Citations (Scopus)

Abstract

Lipoarabinomannans (LAMs) and phosphatidylinositol mannosides (PIMs) are abundant glycolipids in the cell walls of all corynebacteria and mycobacteria, including the devastating human pathogen Mycobacterium tuberculosis. We have recently shown that M. smegmatis mutants of the lipoprotein-encoding lpqW gene have a profound defect in LAM biosynthesis. When these mutants are cultured in complex medium, spontaneous by-pass mutants consistently evolve in which LAM biosynthesis is restored at the expense of polar PIM synthesis. Here we show that restoration of LAM biosynthesis in the lpqW mutant results from secondary mutations in the pimE gene. PimE is a mannosyltransferase involved in converting AcPIM4, a proposed branch point intermediate in the PIM and LAM biosynthetic pathways, to more polar PIMs. Mutations in pimE arose due to insertion of the mobile genetic element ISMsm1 and independent point mutations that were clustered in predicted extracytoplasmic loops of this polytopic membrane protein. Our findings provide the first strong evidence that LpqW is required to channel intermediates such as AcPIM4 into LAM synthesis and that loss of PimE function results in the accumulation of AcPIM4, by-passing the need for LpqW. These data highlight new mechanisms regulating the biosynthetic pathways of these essential cell wall components.
Original languageEnglish
Pages (from-to)3690 - 3699
Number of pages10
JournalJournal of Bacteriology
Volume190
Issue number10
Publication statusPublished - 2008

Cite this

Crellin, P., Kovacevic, S., Martin, K. L., Brammananth, R., Morita, Y. S., Billman-Jacobe, H., ... Coppel, R. L. (2008). Mutations in pimE restore lipoarabinomannan synthesis and growth in a Mycobacterium smegmatis lpqW mutant. Journal of Bacteriology, 190(10), 3690 - 3699.
Crellin, Paul ; Kovacevic, Svetozar ; Martin, Kirstee L ; Brammananth, Rajini ; Morita, Yasu S ; Billman-Jacobe, Helen ; McConville, Malcolm J ; Coppel, Ross Leon. / Mutations in pimE restore lipoarabinomannan synthesis and growth in a Mycobacterium smegmatis lpqW mutant. In: Journal of Bacteriology. 2008 ; Vol. 190, No. 10. pp. 3690 - 3699.
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abstract = "Lipoarabinomannans (LAMs) and phosphatidylinositol mannosides (PIMs) are abundant glycolipids in the cell walls of all corynebacteria and mycobacteria, including the devastating human pathogen Mycobacterium tuberculosis. We have recently shown that M. smegmatis mutants of the lipoprotein-encoding lpqW gene have a profound defect in LAM biosynthesis. When these mutants are cultured in complex medium, spontaneous by-pass mutants consistently evolve in which LAM biosynthesis is restored at the expense of polar PIM synthesis. Here we show that restoration of LAM biosynthesis in the lpqW mutant results from secondary mutations in the pimE gene. PimE is a mannosyltransferase involved in converting AcPIM4, a proposed branch point intermediate in the PIM and LAM biosynthetic pathways, to more polar PIMs. Mutations in pimE arose due to insertion of the mobile genetic element ISMsm1 and independent point mutations that were clustered in predicted extracytoplasmic loops of this polytopic membrane protein. Our findings provide the first strong evidence that LpqW is required to channel intermediates such as AcPIM4 into LAM synthesis and that loss of PimE function results in the accumulation of AcPIM4, by-passing the need for LpqW. These data highlight new mechanisms regulating the biosynthetic pathways of these essential cell wall components.",
author = "Paul Crellin and Svetozar Kovacevic and Martin, {Kirstee L} and Rajini Brammananth and Morita, {Yasu S} and Helen Billman-Jacobe and McConville, {Malcolm J} and Coppel, {Ross Leon}",
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Crellin, P, Kovacevic, S, Martin, KL, Brammananth, R, Morita, YS, Billman-Jacobe, H, McConville, MJ & Coppel, RL 2008, 'Mutations in pimE restore lipoarabinomannan synthesis and growth in a Mycobacterium smegmatis lpqW mutant', Journal of Bacteriology, vol. 190, no. 10, pp. 3690 - 3699.

Mutations in pimE restore lipoarabinomannan synthesis and growth in a Mycobacterium smegmatis lpqW mutant. / Crellin, Paul; Kovacevic, Svetozar; Martin, Kirstee L; Brammananth, Rajini; Morita, Yasu S; Billman-Jacobe, Helen; McConville, Malcolm J; Coppel, Ross Leon.

In: Journal of Bacteriology, Vol. 190, No. 10, 2008, p. 3690 - 3699.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - Mutations in pimE restore lipoarabinomannan synthesis and growth in a Mycobacterium smegmatis lpqW mutant

AU - Crellin, Paul

AU - Kovacevic, Svetozar

AU - Martin, Kirstee L

AU - Brammananth, Rajini

AU - Morita, Yasu S

AU - Billman-Jacobe, Helen

AU - McConville, Malcolm J

AU - Coppel, Ross Leon

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N2 - Lipoarabinomannans (LAMs) and phosphatidylinositol mannosides (PIMs) are abundant glycolipids in the cell walls of all corynebacteria and mycobacteria, including the devastating human pathogen Mycobacterium tuberculosis. We have recently shown that M. smegmatis mutants of the lipoprotein-encoding lpqW gene have a profound defect in LAM biosynthesis. When these mutants are cultured in complex medium, spontaneous by-pass mutants consistently evolve in which LAM biosynthesis is restored at the expense of polar PIM synthesis. Here we show that restoration of LAM biosynthesis in the lpqW mutant results from secondary mutations in the pimE gene. PimE is a mannosyltransferase involved in converting AcPIM4, a proposed branch point intermediate in the PIM and LAM biosynthetic pathways, to more polar PIMs. Mutations in pimE arose due to insertion of the mobile genetic element ISMsm1 and independent point mutations that were clustered in predicted extracytoplasmic loops of this polytopic membrane protein. Our findings provide the first strong evidence that LpqW is required to channel intermediates such as AcPIM4 into LAM synthesis and that loss of PimE function results in the accumulation of AcPIM4, by-passing the need for LpqW. These data highlight new mechanisms regulating the biosynthetic pathways of these essential cell wall components.

AB - Lipoarabinomannans (LAMs) and phosphatidylinositol mannosides (PIMs) are abundant glycolipids in the cell walls of all corynebacteria and mycobacteria, including the devastating human pathogen Mycobacterium tuberculosis. We have recently shown that M. smegmatis mutants of the lipoprotein-encoding lpqW gene have a profound defect in LAM biosynthesis. When these mutants are cultured in complex medium, spontaneous by-pass mutants consistently evolve in which LAM biosynthesis is restored at the expense of polar PIM synthesis. Here we show that restoration of LAM biosynthesis in the lpqW mutant results from secondary mutations in the pimE gene. PimE is a mannosyltransferase involved in converting AcPIM4, a proposed branch point intermediate in the PIM and LAM biosynthetic pathways, to more polar PIMs. Mutations in pimE arose due to insertion of the mobile genetic element ISMsm1 and independent point mutations that were clustered in predicted extracytoplasmic loops of this polytopic membrane protein. Our findings provide the first strong evidence that LpqW is required to channel intermediates such as AcPIM4 into LAM synthesis and that loss of PimE function results in the accumulation of AcPIM4, by-passing the need for LpqW. These data highlight new mechanisms regulating the biosynthetic pathways of these essential cell wall components.

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M3 - Article

VL - 190

SP - 3690

EP - 3699

JO - Journal of Bacteriology

JF - Journal of Bacteriology

SN - 0021-9193

IS - 10

ER -

Crellin P, Kovacevic S, Martin KL, Brammananth R, Morita YS, Billman-Jacobe H et al. Mutations in pimE restore lipoarabinomannan synthesis and growth in a Mycobacterium smegmatis lpqW mutant. Journal of Bacteriology. 2008;190(10):3690 - 3699.