Structural highlights
Publication Abstract from PubMedRecent evidence established that the cell envelope of Mycobacterium tuberculosis, the bacillus causing tuberculosis (TB), is coated by an alpha-glucan-containing capsule that has been implicated in persistence in a mouse infection model. As one of three known metabolic routes to alpha-glucan in mycobacteria, the cytoplasmic GlgE-pathway converts trehalose to alpha(1 --> 4),alpha(1 --> 6)-linked glucan in 4 steps. Whether individual reaction steps, catalyzed by trehalose synthase TreS, maltokinase Pep2, and glycosyltransferases GlgE and GlgB, occur independently or in a coordinated fashion is not known. Here, we report the crystal structure of M. tuberculosis TreS, and show by small-angle X-ray scattering and analytical ultracentrifugation that TreS forms tetramers in solution. Together with Pep2, TreS forms a hetero-octameric complex, and we demonstrate that complex formation markedly accelerates maltokinase activity of Pep2. Thus, complex formation may act as part of a regulatory mechanism of the GlgE pathway, which overall must avoid accumulation of toxic pathway intermediates, such as maltose-1-phosphate, and optimize the use of scarce nutrients. Synthesis of alpha-Glucan in Mycobacteria Involves a Hetero-octameric Complex of Trehalose Synthase TreS and Maltokinase Pep2.,Roy R, Usha V, Kermani A, Scott DJ, Hyde EI, Besra GS, Alderwick LJ, Futterer K ACS Chem Biol. 2013 Aug 13. PMID:23901909[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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