Membrane-anchored substrate binding proteins are deployed in secondary TAXI transporters
| Autor: | Anja Roden, Melanie K. Engelin, Klaas M. Pos, Eric R. Geertsma |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | Biological Chemistry. |
| ISSN: | 1437-4315 1431-6730 |
| DOI: | 10.1515/hsz-2022-0337 |
| Popis: | Substrate-binding proteins (SBPs) are part of solute transport systems and serve to increase substrate affinity and uptake rates. In contrast to primary transport systems, the mechanism of SBP-dependent secondary transport is not well understood. Functional studies have thus far focused on Na+-coupled Tripartite ATP-independent periplasmic (TRAP) transporters for sialic acid. Herein, we report the in vitro functional characterization of TAXIPm-PQM from the human pathogen Proteus mirabilis. TAXIPm-PQM belongs to a TRAP-subfamily using a different type of SBP, designated TRAP-associated extracytoplasmic immunogenic (TAXI) protein. TAXIPm-PQM catalyzes proton-dependent α-ketoglutarate symport and its SBP is an essential component of the transport mechanism. Importantly, TAXIPm-PQM represents the first functionally characterized SBP-dependent secondary transporter that does not rely on a soluble SBP, but uses a membrane-anchored SBP instead. |
| Databáze: | OpenAIRE |
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