Mechanism of ammonia transport by Amt/MEP/Rh: structure of AmtB at 1.35 A.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 15361618.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
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.
Medical subject headings
- Ammonia
- Cation Transport Proteins
- Escherichia coli
- Escherichia coli Proteins