The cell envelope-associated phospholipid-binding protein LmeA is required for mannan polymerization in mycobacteria.

Autor:	Rahlwes KC; From the Department of Microbiology, University of Massachusetts, Amherst, MA 01003., Ha SA; From the Department of Microbiology, University of Massachusetts, Amherst, MA 01003., Motooka D; the Department of Infection Metagenomics, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan., Mayfield JA; the Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02445., Baumoel LR; From the Department of Microbiology, University of Massachusetts, Amherst, MA 01003., Strickland JN; From the Department of Microbiology, University of Massachusetts, Amherst, MA 01003., Torres-Ocampo AP; From the Department of Microbiology, University of Massachusetts, Amherst, MA 01003., Nakamura S; the Department of Infection Metagenomics, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan., Morita YS; From the Department of Microbiology, University of Massachusetts, Amherst, MA 01003, ymorita@microbio.umass.edu.
Jazyk:	angličtina
Zdroj:	The Journal of biological chemistry [J Biol Chem] 2017 Oct 20; Vol. 292 (42), pp. 17407-17417. Date of Electronic Publication: 2017 Aug 29.
DOI:	10.1074/jbc.M117.804377
Abstrakt:	The integrity of the distinguishing, multilaminate cell envelope surrounding mycobacteria is critical to their survival and pathogenesis. The prevalence of phosphatidylinositol mannosides in the cell envelope suggests an important role in the mycobacterial life cycle. Indeed, deletion of the pimE gene (Δ pimE ) encoding the first committed step in phosphatidylinositol hexamannoside biosynthesis in Mycobacterium smegmatis results in the formation of smaller colonies than wild-type colonies on Middlebrook 7H10 agar. To further investigate potential contributors to cell-envelope mannan biosynthesis while taking advantage of this colony morphology defect, we isolated spontaneous suppressor mutants of Δ pimE that reverted to wild-type colony size. Of 22 suppressor mutants, 6 accumulated significantly shorter lipomannan or lipoarabinomannan. Genome sequencing of these mutants revealed mutations in genes involved in the lipomannan/lipoarabinomannan biosynthesis, such as those encoding the arabinosyltransferase EmbC and the mannosyltransferase MptA. Furthermore, we identified three mutants carrying a mutation in a previously uncharacterized gene, MSMEG _ 5785 , that we designated lmeA Complementation of these suppressor mutants with lmeA restored the original Δ pimE phenotypes and deletion of lmeA in wild-type M. smegmatis resulted in smaller lipomannan, as observed in the suppressor mutants. LmeA carries a predicted N-terminal signal peptide, and density gradient fractionation and detergent extractability experiments indicated that LmeA localizes to the cell envelope. Using a lipid ELISA, we found that LmeA binds to plasma membrane phospholipids, such as phosphatidylethanolamine and phosphatidylinositol. LmeA is widespread throughout the Corynebacteriales; therefore, we concluded that LmeA is an evolutionarily conserved cell-envelope protein critical for controlling the mannan chain length of lipomannan/lipoarabinomannan. (© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.)
Databáze:	MEDLINE
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