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- Title
Mechanism of ammonia transport by Amt/MEP/Rh: structure of AmtB at 1.35 A.
- Authors
Khademi, Shahram; O'Connell, Joseph, 3rd; Remis, Jonathan; Robles-Colmenares, Yaneth; Miercke, Larry J W; Stroud, Robert M
- Abstract
The first structure of an ammonia channel from the Amt/MEP/Rh protein superfamily, determined to 1.35 angstrom resolution, shows it to be a channel that spans the membrane 11 times. Two structurally similar halves span the membrane with opposite polarity. Structures with and without ammonia or methyl ammonia show a vestibule that recruits NH4+/NH3, a binding site for NH4+, and a 20 angstrom-long hydrophobic channel that lowers the NH4+ pKa to below 6 and conducts NH3. Favorable interactions for NH3 are seen within the channel and use conserved histidines. Reconstitution of AmtB into vesicles shows that AmtB conducts uncharged NH3.
- Publication
Science (New York, N.Y.), 2004, Vol 305, Issue 5690, p1587
- ISSN
1095-9203
- Publication type
Journal Article
- DOI
10.1126/science.1101952