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Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
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Structure of a MacAB-like efflux pump from Streptococcus pneumoniae
Hong-Bo Yang1,2, Wen-Tao Hou1,2, Meng-Ting Cheng1,2
1Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, China.
Nature Communications
|January 17, 2018
Summary
Streptococcus pneumoniae possesses a novel MacAB-like efflux pump, Spr0693-Spr0695, crucial for antibiotic resistance. Structural analysis reveals its unique mechanism for transporting antimicrobial compounds.
Area of Science:
- Molecular Biology
- Structural Biology
- Microbiology
Background:
- The spr0693-spr0694-spr0695 operon in Streptococcus pneumoniae encodes a potential ATP-binding cassette (ABC)-type efflux pump.
- This efflux pump is implicated in bacterial resistance to antibiotics and antimicrobial peptides.
Purpose of the Study:
- To elucidate the structural basis of the MacAB-like efflux pump in Gram-positive bacteria.
- To understand the transport mechanism of antibiotics and antimicrobial peptides mediated by this efflux system.
Main Methods:
- X-ray crystallography was used to determine the structures of Spr0694-0695 and Spr0693.
- ATPase activity assays and antimicrobial susceptibility testing were performed.
Main Results:
- The crystal structures of the dimeric Spr0694-0695 (ABC transporter) and Spr0693 (nanotube channel) were determined at 3.3 Å and 3.0 Å resolution, respectively.
- A non-canonical ABC transporter fold and a unique transmembrane domain structure were observed.
- A putative substrate-entrance tunnel with lateral access controlled by a guard helix was proposed.
Conclusions:
- The study provides the first structural insights into a MacAB-like efflux pump in Gram-positive bacteria.
- A potential transport mechanism for antimicrobial resistance is proposed, involving the concerted action of the ABC transporter and the nanotube channel.
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