Publication Date:
2004-09-14
Description:
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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Khademi, Shahram -- O'Connell, Joseph 3rd -- Remis, Jonathan -- Robles-Colmenares, Yaneth -- Miercke, Larry J W -- Stroud, Robert M -- GM24485/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2004 Sep 10;305(5690):1587-94.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Biophysics, S412C Genentech Hall, University of California-San Francisco, 600 16th Street, San Francisco, CA 94143-2240, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15361618" target="_blank"〉PubMed〈/a〉
Keywords:
Amino Acid Sequence
;
Ammonia/*metabolism
;
Binding Sites
;
Biological Transport
;
Cation Transport Proteins/*chemistry/genetics/metabolism
;
Cell Membrane/chemistry
;
Crystallization
;
Crystallography, X-Ray
;
Escherichia coli/*chemistry/metabolism
;
Escherichia coli Proteins/*chemistry/genetics/metabolism
;
Hydrogen Bonding
;
Hydrogen-Ion Concentration
;
Hydrophobic and Hydrophilic Interactions
;
Liposomes
;
Membrane Potentials
;
Models, Molecular
;
Molecular Sequence Data
;
Protein Conformation
;
Protein Folding
;
Protein Structure, Quaternary
;
Protein Structure, Secondary
;
Quaternary Ammonium Compounds/metabolism
;
Rh-Hr Blood-Group System/chemistry/metabolism
;
Sequence Alignment
;
Water/chemistry/metabolism
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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