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Published on: March 11, 2021
Caught in a TRAP: substrate-binding proteins in secondary transport
Marcus Fischer1, Qian Yi Zhang, Roderick E Hubbard
1York Structural Biology Laboratory, Department of Chemistry, University of York, York, YO10 5DD, UK.
Trends in Microbiology
|July 27, 2010
Summary
Substrate-binding proteins (SBPs) are crucial for prokaryotic secondary transporters. This study compares over 10 SBP structures, revealing insights into transporter function and evolution, particularly for DctP-type tripartite ATP-independent periplasmic (TRAP) transporters.
Area of Science:
- Biochemistry
- Structural Biology
- Microbiology
Background:
- Substrate-binding protein (SBP)-dependent secondary transporters are widespread in prokaryotes but not well understood.
- Recent structural data for over 10 prokaryotic SBPs provide an opportunity to analyze their roles in transporter function and evolution.
Purpose of the Study:
- To compare the structures of prokaryotic SBPs to elucidate their impact on secondary transporter function and evolution.
- To investigate the structural features and substrate recognition mechanisms of DctP-type TRAP transporters.
Main Methods:
- Comparative structural analysis of over 10 prokaryotic SBPs.
- Focus on seven structures from DctP-type tripartite ATP-independent periplasmic (TRAP) transporters.
- Examination of SBP structures in relation to ATP-binding cassette (ABC) transporter SBPs.
Main Results:
- DctP-TRAP SBPs share similar structures, distinct from ABC transporter SBPs, despite binding diverse substrates.
- A conserved arginine-carboxylate salt bridge is key for substrate recognition in DctP-TRAP SBPs, suggesting evolution for organic acid uptake.
- Two DctP-TRAP SBPs were identified as dimers, raising questions about their functional implications.
Conclusions:
- Multiple SBP families have evolved to partner with secondary transporters.
- The structural findings support the specific evolution of DctP-TRAP transporters for organic acid uptake.
- The dimeric nature of some DctP-TRAP SBPs warrants further investigation into their functional mechanisms.
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