Cystic FibrosisTransmembrane Conductance Regulator and Filamin A Background for “Biochemical Basis...
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Transcript of Cystic FibrosisTransmembrane Conductance Regulator and Filamin A Background for “Biochemical Basis...
Cystic FibrosisTransmembrane Conductance Regulator and Filamin A
Background for “Biochemical Basis of the Interaction between Cystic Fibrosis Transmembrane Conductance Regulator and Immunoglobulin-like Repeats of Filamin” Smith et al. JBC 285 (2010): 17166-17176. Web.
Presented by Amanda Maez
March 9, 2011
Cystic Fibrosis Most common, lethal genetic disorder in
Caucasians characterized by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) of epithelial cells
Characterized by high sweat chloride concentration and dehydrated viscous secretions
Most common mutation is the F508 ~30,000 individuals in North America are
affected (70% carry one copy of F508)
Presentation Overview CFTR
• Location• ABC transporter- general structure• Structure and Function • Mutations
Filamin A Actin binding protein (ABP) Structure
Basis for Research of Smith et al. Mutants are rapidly degraded in ER S13F mutation disrupts CFTR-filamin interaction
CFTR is an ABC Transporter ATP binding cassette
transporter 2 Membrane spanning
domains (MSD1 and MSD2)
2 Nucleotide binding domains (NBD1 and NBD2) Motor
Humans have at least 48 (3-5% of bacterial genome)
K P Locher et al. Science 2002;296:1091-1098
CFTR Structure 2 MSDs
6 membrane-spanning -helices in each 2 NBDs
Each possess an ATP binding pocket ABP1 formed by Walker A and B motifs of NBD1,
ABP2 by Walker A and B motifs of NBD2 Unique regulatory (R) region
Located between the NH2 terminal NBD and the second MSD
Structure of CFTR
Chen, Tsung-Yu, and Tzyh-chang Hwang. "CLC-O and CFTR: Chloride Channels Evolved From Transporters." Physiological Reviews 88 (2008): 351-87. Web
CFTR Function Conducts Cl¯ across
membrane when both NBDs have bound ATP and R domain is phosphorylated by protein kinase A
Closes when ATP is hydrolyzed on one of the NBDs and R domain is no longer phosphorylated.
Lehninger. Principles of Biochemistry. 5th Edition. W.H. Freeman and Company, 2008. 401. Print.
Mutations in CFTR Most common is the F508, which is located in
NBD1 Cause misfolding of the protein which lead to a
defective channel due to inability to hydrolyze ATP Decrease in Cl¯ export is accompanied with a
decrease in export of water and leads to thick, sticky mucus which is a haven for bacteria that are the ultimate cause of mortality
These mutated CFTRs are rapidly transported to and degraded in the ER Those that are not degraded are usually subject to
inefficient trafficking to the apical plasma membrane
Filamin A Structure
High molecular weight Long rod-like domain of 24 repeated anti-
parallel -sheets (resembling immunoglobulin domain)
Two flexible loops (30 aa) that form hinge structures
Fln A Structure
Crystal Structure of C2 Fragment of Steptococcal protein G in complex with FC domain of Human IgG
Details of FlnA-Ig21:CFTR4-
22 crystal structure
Sauer-Eriksson et al. Structure 3 (1995). Web. Smith et al. JBC 285 (2010), Supplemental Figures.
Filamin A Function
Actin Binding Protein (ABP) F-actin crosslinker--scaffolding protein Anchors a variety of transmembrane
proteins to the actin cytoskeleton
Fln A Function
Nakamura et al. JCB 179 (2007): 1011-1025. Web.
Basis for Research of Smith et al.
Mutated CFTRs are rapidly transported to and degraded in the ER Those that are not degraded maintain partial
function, but are usually subject to inefficient trafficking to the apical plasma membrane
Filamin A anchors CFTR to the actin skeleton Understand the interaction between Filamin A
and CFTR using a mutation (S13F) that disrupts this binding
Sources
Chen, Tsung-Yu, and Tzyh-chang Hwang. "CLC-O and CFTR: Chloride Channels Evolved From Transporters." Physiological Reviews 88 (2008): 351-87. Web.
Feng, Yuanyi, and Christopher Walsh. "The Many Faces of Filamin: A Versatile Molecular Scaffold for Cell Motility and Cignaling." Nature Cell Biology 6.11 (2004): 1034-038. Web.
Nakamura et al. “Structural Basis of Filamin A functions.”JCB 179 (2007): 1011-1025. Web.
Locher, Kaspar. "The E. Coli BtuCD Structure: a Framework for ABC Transporter Architecture and Mechanism." Ribbon diagram of the BtuCD protein structure. Science 296 (2002): 1091-098. Web Image.
Sauer-Eriksson, A.E. "Crystal Structure of the C2 Fragment of Streptococcal Protein G in Complex with the Fc Domain of Human IgG." Structure 3 (1995): 265-78. RCSB Protein Data Bank. Web. 8 Mar. 2011.
Smith et al. “Biochemical Basis of the Interaction between Cystic Fibrosis Transmembrane Conductance Regulator and Immunoglobulin-like Repeats of Filamin.” Journal of Biological Chemistry 285 (2010): 17166-17176. Web.
Uribe, Ricardo, and David Jay. "A Review of Actin Binding Proteins: New Perspectives." Molecular Biology Reports 36 (2007): 121-25. Print.