Cryo-EM snapshots of mycobacterial arabinosyltransferase complex EmbB 2 -AcpM 2

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Protein & Cell

RESEARCH ARTICLE Cryo-EM snapshots of mycobacterial arabinosyltransferase complex EmbB2-AcpM2 Lu Zhang1, Yao Zhao2,3,4, Ruogu Gao4,5, Jun Li2, Xiuna Yang2, Yan Gao6, Wei Zhao1, Sudagar S. Gurcha7, Natacha Veerapen7, Sarah M. Batt7, Kajelle Kaur Besra7, Wenqing Xu2, Lijun Bi5, Xian’en Zhang5, Luke W. Guddat8, Haitao Yang2, Quan Wang2,5&, Gurdyal S. Besra7&, Zihe Rao1,2,5,6& State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences and College of Pharmacy, Nankai University, Tianjin 300353, China 2 Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China 3 CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences (CAS), Shanghai 200031, China 4 University of Chinese Academy of Sciences, Beijing 100101, China 5 National Laboratory of Biomacromolecules and Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, CAS, Beijing 100101, China 6 Laboratory of Structural Biology, Tsinghua University, Beijing 100084, China 7 School of Biosciences, Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, UK 8 School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia & Correspondence: [email protected] (Q. Wang), [email protected] (G. S. Besra), [email protected] (Z. Rao) Received November 12, 2019 Accepted November 27, 2019

ABSTRACT Inhibition of Mycobacterium tuberculosis (Mtb) cell wall assembly is an established strategy for anti-TB chemotherapy. Arabinosyltransferase EmbB, which catalyzes the transfer of arabinose from the donor decaprenyl-phosphate-arabinose (DPA) to its arabinosyl acceptor is an essential enzyme for Mtb cell wall synthesis. Analysis of drug resistance mutations suggests that EmbB is the main target of the front-line anti-TB drug, ethambutol. Herein, we report the cryo-EM structures of Mycobacterium smegmatis EmbB in its “resting state” and DPA-bound “active state”. EmbB is a fifteentransmembrane-spanning protein, assembled as a dimer. Each protomer has an associated acyl-carrierprotein (AcpM) on their cytoplasmic surface. Conformational changes upon DPA binding indicate an asymmetric movement within the EmbB dimer during

Lu Zhang, Yao Zhao and Ruogu Gao have contributed equally to this work. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13238-020-00726-6) contains supplementary material, which is available to authorized users.

© The Author(s) 2020

catalysis. Functional studies have identified critical residues in substrate recognition and catalysis, and demonstrated that ethambutol inhibits transferase activity of EmbB by competing with DPA. The structures represent the first step directed towards a rational approach for anti-TB drug discovery.

KEYWORDS Mycobacterium tuberculosis, EmbB, cryoEM, ethambutol, cell wall synthesis, arab