@article {689,
	title = {Controlled expression of branch-forming mannosyltransferase is critical for mycobacterial lipoarabinomannan biosynthesis.},
	journal = {J Biol Chem},
	volume = {285},
	year = {2010},
	month = {2010 Apr 30},
	pages = {13326-36},
	abstract = {Lipomannan (LM) and lipoarabinomannan (LAM) are phosphatidylinositol-anchored glycans present in the mycobacterial cell wall. In Mycobacterium smegmatis, the mannan core of LM/LAM constitutes a linear chain of 20-25 alpha1,6-mannoses elaborated by 8-9 alpha1,2-monomannose side branches. At least two alpha1,6-mannosyltransferases mediate the linear mannose chain elongation, and one branching alpha1,2-mannosyltransferase (encoded by MSMEG_4247) transfers monomannose branches. An MSMEG_4247 deletion mutant accumulates branchless LAM and interestingly fails to accumulate LM, suggesting an unexpected role of mannose branching for LM synthesis or maintenance. To understand the roles of MSMEG_4247-mediated branching more clearly, we analyzed the MSMEG_4247 deletion mutant in detail. Our study showed that the deletion mutant restored the synthesis of wild-type LM and LAM upon the expression of MSMEG_4247 at wild-type levels. In striking contrast, overexpression of MSMEG_4247 resulted in the accumulation of dwarfed LM/LAM, although monomannose branching was restored. The dwarfed LAM carried a mannan chain less than half the length of wild-type LAM and was elaborated by an arabinan that was about 4 times smaller. Induced overexpression of an elongating alpha1,6-mannosyltransferase competed with the overexpressed branching enzyme, alleviating the dwarfing effect of the branching enzyme. In wild-type cells, LM and LAM decreased in quantity in the stationary phase, and the expression levels of branching and elongating mannosyltransferases were reduced in concert, presumably to avoid producing abnormal LM/LAM. These data suggest that the coordinated expressions of branching and elongating mannosyltransferases are critical for mannan backbone elongation.},
	keywords = {Bacterial Proteins, Cell Wall, Gene Deletion, Lipopolysaccharides, Mannose, Mannosyltransferases, Mycobacterium smegmatis},
	issn = {1083-351X},
	doi = {10.1074/jbc.M109.077297},
	author = {Sena, Chubert B C and Fukuda, Takeshi and Miyanagi, Kana and Matsumoto, Sohkichi and Kobayashi, Kazuo and Murakami, Yoshiko and Maeda, Yusuke and Kinoshita, Taroh and Morita, Yasu S}
}
@article {696,
	title = {Compartmentalization of lipid biosynthesis in mycobacteria.},
	journal = {J Biol Chem},
	volume = {280},
	year = {2005},
	month = {2005 Jun 3},
	pages = {21645-52},
	abstract = {The plasma membrane of Mycobacterium sp. is the site of synthesis of several distinct classes of lipids that are either retained in the membrane or exported to the overlying cell envelope. Here, we provide evidence that enzymes involved in the biosynthesis of two major lipid classes, the phosphatidylinositol mannosides (PIMs) and aminophospholipids, are compartmentalized within the plasma membrane. Enzymes involved in the synthesis of early PIM intermediates were localized to a membrane subdomain termed PMf, that was clearly resolved from the cell wall by isopyknic density centrifugation and amplified in rapidly dividing Mycobacterium smegmatis. In contrast, the major pool of apolar PIMs and enzymes involved in polar PIM biosynthesis were localized to a denser fraction that contained both plasma membrane and cell wall markers (PM-CW). Based on the resistance of the PIMs to solvent extraction in live but not lysed cells, we propose that polar PIM biosynthesis occurs in the plasma membrane rather than the cell wall component of the PM-CW. Enzymes involved in phosphatidylethanolamine biosynthesis also displayed a highly polarized distribution between the PMf and PM-CW fractions. The PMf was greatly reduced in non-dividing cells, concomitant with a reduction in the synthesis and steady-state levels of PIMs and amino-phospholipids and the redistribution of PMf marker enzymes to non-PM-CW fractions. The formation of the PMf and recruitment of enzymes to this domain may thus play a role in regulating growth-specific changes in the biosynthesis of membrane and cell wall lipids.},
	keywords = {Bacterial Proteins, Biochemistry, Cell Membrane, Cell Wall, Hemagglutinins, Lipid Metabolism, Lipids, Mannosides, Mannosyltransferases, Microscopy, Electron, Models, Biological, Mycobacterium smegmatis, Phosphatidylethanolamines, Phosphatidylinositols, Phospholipids, Protein Structure, Tertiary, Subcellular Fractions},
	issn = {0021-9258},
	doi = {10.1074/jbc.M414181200},
	author = {Morita, Yasu S and Velasquez, Ren{\'e} and Taig, Ellen and Waller, Ross F and Patterson, John H and Tull, Dedreia and Williams, Spencer J and Billman-Jacobe, Helen and McConville, Malcolm J}
}
