Conformational Changes in a Macrolide Antibiotic Binding Protein From Mycobacterium smegmatis Upon ADP Binding.

Qingqing Zhang,Zihe Rao,Bingjie Zhang,Huijuan Liu,Luke W Guddat,Xiang Liu,Haitao Yang,Kaixia Mi

doi:10.3389/fmicb.2021.780954

Abstract

Rv3197 (MABP-1), a non-canonical ABC protein in Mycobacterium tuberculosis, has ATPase activity and confers inducible resistance to the macrolide family of antibiotics. Here we have shown that MSMEG_1954, the homolog of Rv3197 in M. smegmatis, has a similar function of conferring macrolide resistance. Crystal structures of apo-MSMEG_1954 (form1 and form 2) and MSMEG_1954 in complex with ADP have been determined. These three structures show that MSMEG_1954 has at least two different conformations we identify as closed state (MSMEG_1954-form 1) and open state (MSMEG_1954-form 2 and MSMEG_1954-ADP). Structural superimposition shows that the MSMEG_1954-form 2 and MSMEG_1954-ADP complex have similar conformation to that observed for MABP-1 and MABP-1-erythromicin complex structure. However, the antibiotic binding pocket in MSMEG_1954-form 1 is completely blocked by the N-terminal accessory domain. When bound by ADP, the N-terminal accessory domain undergoes conformational change, which results in the open of the antibiotic binding pocket. Because of the degradation of N terminal accessory domain in MSMSG_1954-form 2, it is likely to represent a transitional state between MSMEG_1954-form 1 and MSMEG_1954-ADP complex structure.

Highlights

Tuberculosis (TB) is an infectious disease that is one of the top 10 causes of death worldwide (World Health Organization (WHO), 2018)
We have shown Mycobacterium tuberculosis (MTB) has evolved a non-canonical ATP-binding cassette (ABC) protein, Rv3197, identified as macrolide antibiotic binding protein-1 (MABP1), which confers inducible resistance to the macrolide family of antibiotics (Zhang et al, 2018)
These results indicate that MSMEG_1954 is induced in response to macrolide exposure and under the overexpression scenario tested here, appears to provide resistance in M. smegmatis just like macrolide antibiotic binding protein-1 (MABP-1) in Mycobacterium tuberculosis

Summary

Introduction

Tuberculosis (TB) is an infectious disease that is one of the top 10 causes of death worldwide (World Health Organization (WHO), 2018). Mycobacteria has developed diverse strategies to acquire resistance to the most widely used antibiotics (Alekshun and Levy, 2007; Goldberg et al, 2012; Blair et al, 2015), including antibiotic target protection by site-of-action mutations (Vilcheze and Jacobs, 2014) or by chemical modification of the target; the direct modification or inactivation of antibiotics by specific enzymes (e.g., hydrolases, phosphotransferases); the reduced cell-wall permeability (Goude and Parish, 2008) or increased efflux of the drugs (Braibant et al, 2000; De Rossi et al, 2006; da Silva et al, 2011; Black et al, 2014), which prevents the drug from gaining access to the target. ATP-binding cassette (ABC) families are important mediators of drug resistance in micro-organisms. Their function is to pump drugs out of the cell, thereby rendering them ineffective

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Conclusion