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PDBsum entry 6cse
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Membrane protein
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PDB id
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6cse
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Contents |
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214 a.a.
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213 a.a.
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431 a.a.
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References listed in PDB file
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Key reference
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Title
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Structural basis for substrate binding and specificity of a sodium-Alanine symporter agcs.
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Authors
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J.Ma,
H.T.Lei,
F.E.Reyes,
S.Sanchez-Martinez,
M.F.Sarhan,
J.Hattne,
T.Gonen.
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Ref.
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Proc Natl Acad Sci U S A, 2019,
116,
2086-2090.
[DOI no: ]
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PubMed id
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Abstract
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The amino acid, polyamine, and organocation (APC) superfamily is the second
largest superfamily of membrane proteins forming secondary transporters that
move a range of organic molecules across the cell membrane. Each transporter in
the APC superfamily is specific for a unique subset of substrates, even if they
possess a similar structural fold. The mechanism of substrate selectivity
remains, by and large, elusive. Here, we report two crystal structures of an APC
member from Methanococcus maripaludis, the alanine or glycine:cation
symporter (AgcS), with l- or d-alanine bound. Structural analysis combined with
site-directed mutagenesis and functional studies inform on substrate binding,
specificity, and modulation of the AgcS family and reveal key structural
features that allow this transporter to accommodate glycine and alanine while
excluding all other amino acids. Mutation of key residues in the substrate
binding site expand the selectivity to include valine and leucine. These studies
provide initial insights into substrate selectivity in AgcS symporters.
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