The Key Roles of Mycobacterium tuberculosis FadD23 C-terminal Domain in Catalytic Mechanisms

Mengrong Yan; Lin Cao; Li Zhao; Weihong Zhou; Xiang Liu; Wei Zhang; Zihe Rao

doi:10.3389/fmicb.2023.1090534

The Key Roles of Mycobacterium tuberculosis FadD23 C-terminal Domain in Catalytic Mechanisms

Front Microbiol. 2023 Feb 21:14:1090534. doi: 10.3389/fmicb.2023.1090534. eCollection 2023.

Authors

Mengrong Yan¹, Lin Cao¹, Li Zhao², Weihong Zhou¹, Xiang Liu¹, Wei Zhang², Zihe Rao^{1

2

3

4}

Affiliations

¹ State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin, China.
² Innovative Center for Pathogen Research, Guangzhou Laboratory, Guangzhou, China.
³ Shanghai Institute for Advanced Immunochemical Studies and School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China.
⁴ Laboratory of Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing, China.

Abstract

Sulfolipid-1 (SL-1) is located in the Mycobacterium tuberculosis (M. tb) cell wall, and is essential for pathogen virulence and intracellular growth. Multiple proteins (e.g., Pks2, FadD23, PapA1, and MmpL8) in the SL-1 synthesis pathway can be treated as drug targets, but, to date, their structures have not been solved. The crystal structures of FadD23 bound to ATP or hexadecanoyl adenylate was determined in this study. We have also investigated long-chain saturated fatty acids as biological substrates of FadD23 through structural, biological, and chemical analyses. The mutation at the active site of FadD23 greatly influences enzymatic activity. Meanwhile, the FadD23 N-terminal domain alone cannot bind palmitic acid without C-terminal domain facilitation since it is almost inactive after removing the C-terminal domain. FadD23 is the first protein in the SL-1 synthesis pathway whose structure has been solved. These results reveal the importance of the C-terminal domain in the catalytic mechanism.

Keywords: catalytic mechanism; crystal structure; enzymatic activity; fatty acid adenylating enzyme; sulfolipid-1.