The MCR-3 inside linker appears as a facilitator of colistin resistance
Yongchang Xu,
Haiyi Chen,
Huimin Zhang,
Saif Ullah,
Tingjun Hou,
Youjun Feng
Affiliations
Yongchang Xu
Department of Pathogen Biology & Microbiology, Department of General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
Haiyi Chen
Hangzhou Institute of Innovative Medicine, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
Huimin Zhang
Department of Pathogen Biology & Microbiology, Department of General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
Saif Ullah
Department of Pathogen Biology & Microbiology, Department of General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
Tingjun Hou
Hangzhou Institute of Innovative Medicine, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China; Corresponding author
Youjun Feng
Department of Pathogen Biology & Microbiology, Department of General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China; Corresponding author
Summary: An evolving family of mobile colistin resistance (MCR) enzymes is threatening public health. However, the molecular mechanism by which the MCR enzyme as a rare member of lipid A-phosphoethanolamine (PEA) transferases gains the ability to confer phenotypic colistin resistance remains enigmatic. Here, we report an unusual example that genetic duplication and amplification produce a functional variant (Ah762) of MCR-3 in certain Aeromonas species. The lipid A-binding cavity of Ah762 is functionally defined. Intriguingly, we locate a hinge linker of Ah762 (termed Linker 59) that determines the MCR. Genetic and biochemical characterization reveals that Linker 59 behaves as a facilitator to render inactive MCR variants to regain the ability of colistin resistance. Along with molecular dynamics (MD) simulation, isothermal titration calorimetry (ITC) suggests that this facilitator guarantees the formation of substrate phosphatidylethanolamine (PE)-accessible pocket within MCR-3-like enzymes. Therefore, our finding defines an MCR-3 inside facilitator for colistin resistance.
