TRP_2, a lipid/trafficking domain that mediates diacylglycerol-induced vesicle fusion.
We recently modeled transient receptor potential (TRP) channels using the Gestalt Domain Detection Algorithm-Basic Local Alignment Tool (GDDA-BLAST), which derives structural, functional, and evolutionary information from primary amino acid sequences using phylogenetic profiles ( Ko, K. D., Hong, Y., Chang, G. S., Bhardwaj, G., van Rossum, D. B., and Patterson, R. L. (2008) Physics Arch. Quant. Methods arXiv: 0806.2394v1 ). Herein we test our functional predictions for the TRP_2 domain of TRPC3; a domain of unknown function that is conserved in all TRPC channels. Our functional models of this domain identify both lipid binding and trafficking activities. In this study, we reveal: (i) a novel structural determinant of ion channel sensitivity to lipids, (ii) a molecular mechanism for the difference between diacylglycerol (DAG)-sensitive and DAG-insensitive TRPC subfamilies, and (iii) evidence that TRPC3 can comprise part of the vesicle fusion machinery. Indeed, the TRPC3 TRP_2 domain mediates channel trafficking to the plasma membrane and binds to plasma membrane lipids. Further, mutations in TRP_2, which alter lipid binding, also disrupt the DAG-mediated fusion of TRPC3-containing vesicles with the plasma membrane without disrupting SNARE interactions. Importantly, these data agree with the known role of DAG in membrane destabilization, which facilitates SNARE-dependent synaptic vesicle fusion ( Villar, A. V., Goni, F. M., and Alonso, A. (2001) FEBS Lett. 494, 117-120 and Goni, F. M., and Alonso, A. (1999) Prog. Lipid Res. 38, 1-48 ). Taken together, functional models generated by GDDA-BLAST provide a computational platform for deriving domain functionality, which can have in vivo and mechanistic relevance.
van Rossum
Damian B
DB
Center for Computational Proteomics and Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Oberdick
Daniel
D
Rbaibi
Youssef
Y
Bhardwaj
Gaurav
G
Barrow
Roxanne K
RK
Nikolaidis
Nikolas
N
Snyder
Solomon H
SH
Kiselyov
Kirill
K
Patterson
Randen L
RL
D000595:Amino Acid Sequence; D019921:Biotinylation; D002118:Calcium / Q000378:metabolism; D004075:Diglycerides / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D008055:Lipids / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry; D018613:Microscopy, Confocal; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D050052:TRPC Cation Channels / Q000737:chemistry* / Q000502:physiology*
D004075:Diglycerides; D008055:Lipids; D008081:Liposomes; D050052:TRPC Cation Channels; C104603:TRPC3 cation channel; D002118:Calcium