Structural basis for conductance by the archaeal aquaporin AqpM at 1.68 A.
To explore the structural basis of the unique selectivity spectrum and conductance of the transmembrane channel protein AqpM from the archaeon Methanothermobacter marburgensis, we determined the structure of AqpM to 1.68-A resolution by x-ray crystallography. The structure establishes AqpM as being in a unique subdivision between the two major subdivisions of aquaporins, the water-selective aquaporins, and the water-plus-glycerol-conducting aquaglyceroporins. In AqpM, isoleucine replaces a key histidine residue found in the lumen of water channels, which becomes a glycine residue in aquaglyceroporins. As a result of this and other side-chain substituents in the walls of the channel, the channel is intermediate in size and exhibits differentially tuned electrostatics when compared with the other subfamilies.
Lee
John K
JK
Macromolecular Structure Group, Department of Biochemistry and Biophysics, University of California, S-412C Genentech Hall, 600 16th Street, San Francisco, CA 94143-2240, USA.
Kozono
David
D
Remis
Jonathan
J
Kitagawa
Yoshichika
Y
Agre
Peter
P
Stroud
Robert M
RM
D000595:Amino Acid Sequence; D020346:Aquaporins / Q000737:chemistry* / Q000378:metabolism; D001105:Archaea / Q000378:metabolism*; D018360:Crystallography, X-Ray; D003902:Detergents / Q000494:pharmacology; D005990:Glycerol / Q000737:chemistry; D005998:Glycine / Q000737:chemistry; D006358:Hot Temperature; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008081:Liposomes / Q000737:chemistry; D017013:Methanobacteriaceae / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry; D013997:Time Factors; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
D020346:Aquaporins; D003902:Detergents; D008081:Liposomes; D011994:Recombinant Proteins; D014867:Water; D005990:Glycerol; D005998:Glycine