Biosynthesis of mycobacterial methylmannose polysaccharides requires a unique 1-O-methyltransferase specific for 3-O-methylated mannosides

作     者：Ripoll-Rozada, Jorge Costa, Mafalda Manso, Jose A. Maranha, Ana Miranda, Vanessa Sequeira, Andre Rita Ventura, M. Macedo-Ribeiro, Sandra Barbosa Pereira, Pedro Jose Empadinhas, Nuno 

作者机构：Univ Porto Inst Biol Mol & Celular IBMC P-4200135 Porto Portugal Univ Porto Inst Invest & Inovacao Saude P-4200135 Porto Portugal Univ Coimbra Ctr Neurosci & Cell Biol CNC P-3004504 Coimbra Portugal Univ Coimbra Inst Interdisciplinary Res IIIUC PhD Program Expt Biol & Biomed PDBEB P-3030789 Coimbra Portugal Univ Nova Lisboa Inst Tecnol Quim Biol Bioorgan Chem Grp P-2780157 Oeiras Portugal Univ Coimbra Inst Interdisciplinary Res IIIC P-3030789 Coimbra Portugal 

出 版 物：《PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA》 (美国国家科学院汇刊)

年 卷 期：2019年第116卷第3期

页      面：835-844页

核心收录：

学科分类：07[理学] 08[工学] 

基　　金：CALIPSOplus Fundacao para a Ciencia e a Tecnologia (Portugal) [SFRH/BD/101191/2014] European Social Fund through Programa Operacional Capital Humano [SFRH/BPD/108004/2015] European Regional Development Fund (FEDER), through Centro2020 Project [CENTRO-01-0145-FEDER-000012-HealthyAging2020] COMPETE 2020-Operational Programme for Competitiveness and Internationalization (POCI), PORTUGAL 2020 [POCI-01-0145-FEDER-029221 (PTDC/BTM-TEC/29221/2017)] Institute for Research and Innovation in Health Sciences [POCI-01-0145-FEDER-007274, UID/NEU/04539/2013] Research Unit MOSTMICRO [UID/CQB/04612/2013] "Structured program on bioengineered therapies for infectious diseases and tissue regeneration" - Norte Portugal Regional Operational Programme (NORTE 2020) under FEDER [Norte-01-0145-FEDER-000012] FCT through the Portugese National Investment program (PIDDAC) FEDER through COMPETE 2020, POCI, PORL X-ray Crystallography Biochemical and Biophysical Technologies Scientific Platforms of i3S (Porto, Portugal) Fundação para a Ciência e a Tecnologia [SFRH/BPD/108004/2015, SFRH/BD/101191/2014] Funding Source: FCT 

主　　题：Mycobacterium polymethylated polysaccharides sugar methyltransferase S-adenosyl-L-methionine 3D structure 

摘      要：Mycobacteria are a wide group of organisms that includes strict pathogens, such as Mycobacterium tuberculosis, as well as environmental species known as nontuberculous mycobacteria (NTM), some of which-namely Mycobacterium avium-are important opportunistic pathogens. In addition to a distinctive cell envelope mediating critical interactions with the host immune system and largely responsible for their formidable resistance to antimicrobials, mycobacteria synthesize rare intracellular polymethylated polysaccharides implicated in the modulation of fatty acidmetabolism, thus critical players in cell envelope assembly. These are the 6-O-methylglucose lipopolysaccharides (MGLP) ubiquitously detected across the Mycobacterium genus, and the 3-O-methylmannose polysaccharides (MMP) identified only in NTM. The polymethylated nature of these polysaccharides renders the intervening methyltransferases essential for their optimal function. Although the knowledge of MGLP biogenesis is greater than that of MMP biosynthesis, the methyltransferases of both pathways remain uncharacterized. Here, we report the identification and characterization of a unique S-adenosyl-L-methionine-dependent sugar 1-O-methyltransferase (MeT1) from Mycobacterium hassiacum that specifically blocks the 1-OH position of 3,3 -di-O-methyl-4a-mannobiose, a probable early precursor ofMMP, whichwe chemically synthesized. The highresolution 3D structure of MeT1 in complex with its exhausted cofactor, S-adenosyl-L-homocysteine, together with mutagenesis studies and molecular docking simulations, unveiled the enzyme s reaction mechanism. The functional and structural properties of this unique sugar methyltransferase further our knowledge of MMP biosynthesis and provide important tools to dissect the role of MMP in NTM physiology and resilience.