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Biochim Biophys Acta Biomembr. 2017 Feb;1859(2):289-293. doi: 10.1016/j.bbamem.2016.11.013. Epub 2016 Nov 30.

Specific stabilization of CFTR by phosphatidylserine.

Author information

1
Department of Cell Biology and Biochemistry, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, 3601 4th Street, Stop 6540, Lubbock, TX 79430, USA. Electronic address: ellen.hildebrandt@ttuhsc.edu.
2
Department of Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel. Electronic address: netalyk@gmail.com.
3
Department of Medicine, University of Alabama at Birmingham, 701 19th Street South, Birmingham, AL 35294-0007, USA; Birmingham Veterans Medical Center, Research Service, Birmingham, AL 35233, USA. Electronic address: kappesjc@uab.edu.
4
Department of Medicine, University of Alabama at Birmingham, 701 19th Street South, Birmingham, AL 35294-0007, USA. Electronic address: daiq@uab.edu.
5
Department of Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel. Electronic address: hanoch@biu.ac.il.
6
Department of Cell Biology and Biochemistry, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, 3601 4th Street, Stop 6540, Lubbock, TX 79430, USA. Electronic address: ina.urbatsch@ttuhsc.edu.

Abstract

The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR, ABCC7) is a plasma membrane chloride ion channel in the ABC transporter superfamily. CFTR is a key target for cystic fibrosis drug development, and its structural elucidation would advance those efforts. However, the limited in vivo and in vitro stability of the protein, particularly its nucleotide binding domains, has made structural studies challenging. Here we demonstrate that phosphatidylserine uniquely stimulates and thermally stabilizes the ATP hydrolysis function of purified human CFTR. Among several lipids tested, the greatest stabilization was observed with brain phosphatidylserine, which shifted the Tm for ATPase activity from 22.7±0.8°C to 35.0±0.2°C in wild-type CFTR, and from 26.6±0.7°C to 42.1±0.2°C in a more stable mutant CFTR having deleted regulatory insertion and S492P/A534P/I539T mutations. When ATPase activity was measured at 37°C in the presence of brain phosphatidylserine, Vmax for wild-type CFTR was 240±60nmol/min/mg, a rate higher than previously reported and consistent with rates for other purified ABC transporters. The significant thermal stabilization of CFTR by phosphatidylserine may be advantageous in future structural and biophysical studies of CFTR.

KEYWORDS:

ABC transporters; ATP hydrolysis; Blind docking; Cystic Fibrosis Transmembrane Conductance Regulator; Phosphatidylserine; Thermal stability

PMID:
27913277
PMCID:
PMC5237360
DOI:
10.1016/j.bbamem.2016.11.013
[Indexed for MEDLINE]
Free PMC Article

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