Structural basis for amino acid transport by the CAT family of SLC7 transporters.
Nat Commun 2018;
9:550. [PMID:
29416041 PMCID:
PMC5803215 DOI:
10.1038/s41467-018-03066-6]
[Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 01/17/2018] [Indexed: 12/12/2022] Open
Abstract
Amino acids play essential roles in cell biology as regulators of metabolic pathways. Arginine in particular is a major signalling molecule inside the cell, being a precursor for both l-ornithine and nitric oxide (NO) synthesis and a key regulator of the mTORC1 pathway. In mammals, cellular arginine availability is determined by members of the solute carrier (SLC) 7 family of cationic amino acid transporters. Whereas CAT-1 functions to supply cationic amino acids for cellular metabolism, CAT-2A and -2B are required for macrophage activation and play important roles in regulating inflammation. Here, we present the crystal structure of a close homologue of the mammalian CAT transporters that reveals how these proteins specifically recognise arginine. Our structural and functional data provide a model for cationic amino acid transport in mammalian cells and reveals mechanistic insights into proton-coupled, sodium-independent amino acid transport in the wider APC superfamily.
Cationic amino acid transporters (CATs) belong to the physiologically important solute carrier (SLC) 7 family. Here, the authors present the structure of the mammalian CAT transporter homologue Geobacillus kaustophilus GkApcT, which reveals how arginine is recognized, and propose a model for proton-coupled amino acid transport.
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