RT Journal Article SR Electronic T1 Structure of Mycobacterium tuberculosis Cya, an evolutionary ancestor of the mammalian membrane adenylyl cyclases JF bioRxiv FD Cold Spring Harbor Laboratory SP 2021.12.01.470738 DO 10.1101/2021.12.01.470738 A1 Ved Mehta A1 Basavraj Khanppnavar A1 Dina Schuster A1 Irene Vercellino A1 Angela Kosturanova A1 Tarun Iype A1 Sasa Stefanic A1 Paola Picotti A1 Volodymyr M. Korkhov YR 2021 UL http://biorxiv.org/content/early/2021/12/01/2021.12.01.470738.abstract AB Mycobacterium tuberculosis adenylyl cyclase (AC) Cya is an evolutionary ancestor of the mammalian membrane ACs and a model system for studies of their structure and function. Although the vital role of ACs in cellular signaling is well established, the function of their transmembrane (TM) regions remains unknown. Here we describe the cryo-EM structure of Cya bound to a stabilizing nanobody at 3.6 Å resolution. The TM helices 1-5 form a structurally conserved domain that facilitates the assembly of the helical and catalytic domains. The TM region contains discrete pockets accessible from the extracellular and cytosolic side of the membrane. Neutralization of the negatively charged extracellular pocket Ex1 destabilizes the cytosolic helical domain and reduces the catalytic activity of the enzyme. The TM domain acts as a functional component of Cya, guiding the assembly of the catalytic domain and providing the means for direct regulation of catalytic activity in response to extracellular ligands.One-Sentence Summary Cryo-EM structure of M. tuberculosis adenylyl cyclase Cya provides clues to the role of its transmembrane domainCompeting Interest StatementThe authors have declared no competing interest.