Essential helix interactions in the anion transporter domain of prestin revealed by evolutionary trace analysis.
Prestin, a member of the SLC26A family of anion transporters, is a polytopic membrane protein found in outer hair cells (OHCs) of the mammalian cochlea. Prestin is an essential component of the membrane-based motor that enhances electromotility of OHCs and contributes to frequency sensitivity and selectivity in mammalian hearing. Mammalian cells expressing prestin display a nonlinear capacitance (NLC), widely accepted as the electrical signature of electromotility. The associated charge movement requires intracellular anions reflecting the membership of prestin in the SLC26A family. We used the computational approach of evolutionary trace analysis to identify candidate functional (trace) residues in prestin for mutational studies. We created a panel of mutations at each trace residue and determined membrane expression and nonlinear capacitance associated with each mutant. We observe that several residue substitutions near the conserved sulfate transporter domain of prestin either greatly reduce or eliminate NLC, and the effect is dependent on the size of the substituted residue. These data suggest that packing of helices and interactions between residues surrounding the "sulfate transporter motif" is essential for normal prestin activity.
Rajagopalan
Lavanya
L
Department of Molecular Virology, Baylor College of Medicine, Houston, Texas 77030, USA.
Patel
Nimish
N
Madabushi
Srinivasan
S
Goddard
Julie Anne
JA
Anjan
Venkat
V
Lin
Feng
F
Shope
Cindy
C
Farrell
Brenda
B
Lichtarge
Olivier
O
Davidson
Amy L
AL
Brownell
William E
WE
Pereira
Fred A
FA
D000595:Amino Acid Sequence; D000818:Animals; D027321:Anion Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D019020:Directed Molecular Evolution / Q000379:methods*; D019143:Evolution, Molecular; D005849:Gerbillinae; D006801:Humans; D008969:Molecular Sequence Data; D027361:Organic Anion Transporters / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D025941:Protein Interaction Mapping; D017433:Protein Structure, Secondary / Q000235:genetics; D048790:Renilla; D013329:Structure-Activity Relationship; D000076988:Sulfate Transporters
D027321:Anion Transport Proteins; D027361:Organic Anion Transporters; C498719:SLC26A5 protein, human; D000076988:Sulfate Transporters