John Riordan, PhD

Distinguished Professor

Specialty Areas: Structure, Function and Biosynthetic Processing of Membrane Proteins

Research Focus: The primary research focus is the structure, function, and biosynthetic processing of membrane proteins that provide permeability pathways through the membranes of cells. Much of our current work is concentrated on the ion channel protein which is absent or dysfunctional in patients with cystic fibrosis. All patients have mutations in the gene that codes for this protein, CFTR (cystic fibrosis transmembrane conductance regulator).Structure, Function And Biosynthetic Processing Of Membrane Proteins

CFTR is a secretory channel that plays a central role in maintaining fluid balance in several tissues, including the lung airways, the intestines, and many exocrine glands such as the pancreas and salivary glands. To elucidate the molecular mechanisms of CFTR function, we study its single channel properties by electrophysiological techniques. The enzymatic activity is studied after purification of the recombinant protein generated in different cultured cell systems. Isolation of the molecule by single step methods employing antibodies and other manipulations also enables investigation of CFTR’s interaction with other cellular molecules. A major objective of studies with the purified CFTR molecule is to obtain 3-dimensional structure information so that small molecules capable of recognizing features of its surface shape can be synthesized and used to modulate its folding and activity. CFTR interaction partners that are important in CFTR function and biosynthesis are being identified by proteomic methods.

Selected Bibliography:

  1. Sigoillot M, Overtus M, Grodecka M, Scholl D, Garcia-Pino A, Laeremans T, He L, Pardon E, Hildebrandt E, Urbatsch I, Steyaert J, Riordan JR, Govaerts C. Domain-interface dynamics of CFTR revealed by stabilizing nanobodies. Nat Commun. 2019 Jun 14;10(1):2636. doi: 10.1038/s41467-019-10714-y. PMID: 31201318. PMCID: PMC6572788.
  2. Fay JF, Aleksandrov LA, Jensen TJ, Cui LL, Kousouros JN, He L, Aleksandrov AA, Gingerich DS, Riordan JR, Chen JZ. Cryo-EM Visualization of an Active High Open Probability CFTR Anion Channel. Biochemistry. 2018 Oct 30;57(43):6234-6246. doi: 10.1021/acs.biochem.8b00763. PMID: 30281975.
  3. Aleksandrov LA, Fay JF, Riordan JR. R-Domain Phosphorylation by Protein Kinase A Stimulates Dissociation of Unhydrolyzed ATP from the First Nucleotide-Binding Site of the Cystic Fibrosis Transmembrane Conductance Regulator. Biochemistry. 2018 Aug 28;57(34):5073-5075. doi: 10.1021/acs.biochem.8b00646. PMID: 30109929.
  4. Wang C, Aleksandrov AA, Yang Z, Forouhar F, Proctor EA, Kota P, An J, Kaplan A, Khazanov N, Boël G, Stockwell BR, Senderowitz H, Dokholyan NV, Riordan JR, Brouillette CG, Hunt JF. Ligand binding to a remote site thermodynamically corrects the F508del mutation in the human cystic fibrosis transmembrane conductance regulator. J Biol Chem. 2018 Nov 16;293(46):17685-17704. doi: 10.1074/jbc.RA117.000819. PMID: 29903914. PMCID: PMC6240863.
  5. Yang Z, Hildebrandt E, Jiang F, Aleksandrov AA, Khazanov N, Zhou Q, An J, Mezzell AT, Xavier BM, Ding H, Riordan JR, Senderowitz H, Kappes JC, Brouillette CG, Urbatsch IL. Structural stability of purified human CFTR is systematically improved by mutations in nucleotide binding domain 1. Biochim Biophys Acta Biomembr. 2018 May;1860(5):1193-1204. doi: 10.1016/j.bbamem.2018.02.006. PMID: 29425673. PMCID: PMC6319260.
  6. Ma P, Weichert D, Aleksandrov LA, Jensen TJ, Riordan JR, Liu X, Kobilka BK, Caffrey M. The cubicon method for concentrating membrane proteins in the cubic mesophase. Nat Protoc. 2017 Sep;12(9):1745-1762. doi: 10.1038/nprot.2017.057. PMID: 28771236.
  7. Vernon RM, Chong PA, Lin H, Yang Z, Zhou Q, Aleksandrov AA, Dawson JE, Riordan JR, Brouillette CG, Thibodeau PH, Forman-Kay JD. Stabilization of a nucleotide-binding domain of the cystic fibrosis transmembrane conductance regulator yields insight into disease-causing mutations. J Biol Chem. 2017 Aug 25;292(34):14147-14164. doi: 10.1074/jbc.M116.772335. PMID: 28655774. PMCID: PMC5572908.
  8. Das J, Aleksandrov AA, Cui L, He L, Riordan JR, Dokholyan NV. Transmembrane helical interactions in the CFTR channel pore. PLoS Comput Biol. 2017 Jun 22;13(6):e1005594. doi: 10.1371/journal.pcbi.1005594. PMID: 28640808. PMCID: PMC5501672.
  9. Gakhal AK, Jensen TJ, Bozoky Z, Roldan A, Lukacs GL, Forman-Kay J, Riordan JR, Sidhu SS. Development and characterization of synthetic antibodies binding to the cystic fibrosis conductance regulator. MAbs. 2016 Aug-Sep;8(6):1167-76. doi: 10.1080/19420862.2016.1186320. PMID: 27185291. PMCID: PMC4968092.
  10. Billet A, Jia Y, Jensen TJ, Hou YX, Chang XB, Riordan JR, Hanrahan JW. Potential sites of CFTR activation by tyrosine kinases. Channels (Austin). 2016;10(3):247-51. doi: 10.1080/19336950.2015.1126010. PMID: 26645934. PMCID: PMC4954566.
  11. Aleksandrov LA, Jensen TJ, Cui L, Kousouros JN, He L, Aleksandrov AA, Riordan JR. Thermal stability of purified and reconstituted CFTR in a locked open channel conformation. Protein Expr Purif. 2015 Dec;116:159-66. doi: 10.1016/j.pep.2015.09.018. PMID: 26384709; PMCID: PMC4661089.
  12. Billet A, Jia Y, Jensen T, Riordan JR, Hanrahan JW. Regulation of the cystic fibrosis transmembrane conductance regulator anion channel by tyrosine phosphorylation. FASEB J. 2015 Sep;29(9):3945-53. doi: 10.1096/fj.15-273151. PMID: 26062600; PMCID: PMC4550374.
  13. Proctor EA, Kota P, Aleksandrov AA, He L, Riordan JR, Dokholyan NV. Rational doupled dynamics network manipulation rescues disease-relevant mutant cystic fibrosis transmembrane conductance regulator. Chem Sci. 2015 Feb;6(2):1237-1246. PMID: 25685315; PMCID: PMC4324596.
  14. He L, Aleksandrov AA, An J, Cui L, Yang Z, Brouillette CG, Riordan JR. Restoration of NBD1 thermal stability is necessary and sufficient to correct ∆F508 CFTR folding and assembly. J Mol Biol. 2015 Jan 16;427(1):106-20. doi: 10.1016/j.jmb.2014.07.026. PMID: 25083918.
  15. O’Riordan TG, Donn KH, Hodsman P, Ansede JH, Newcomb T, Lewis SA, Flitter WD, White VS, Johnson MR, Montgomery AB, Warnock DG, Boucher RC. Acute hyperkalemia associated with inhalation of a potent ENaC antagonist: Phase 1 trial of GS-9411. J Aerosol Med Pulm Drug Deliv. 2014 Jun;27(3):200-8. doi: 10.1089/jamp.2013.1037. PMID: 23905576.
  16. Esther CR Jr, Boucher RC, Johnson MR, Ansede JH, Donn KH, O’Riordan TG, Ghio AJ, Hirsh AJ. Airway drug pharmacokinetics via analysis of exhaled breath condensate. Pulm Pharmacol Ther. 2014 Feb;27(1):76-82. doi: 10.1016/j.pupt.2013.07.009. PMID: 23932897; PMCID: PMC3947122.
  17. He L, Aleksandrov LA, Cui L, Jensen TJ, Nesbitt KL, Riordan JR. Restoration of domain folding and interdomain assembly by second-site suppressors of the DeltaF508 mutation in CFTR. FASEB J. 2010 Aug;24(8):3103-12. doi: 10.1096/fj.09-141788. PMID: 20233947; PMCID: PMC2909275.
  18. Aleksandrov AA, Kota P, Aleksandrov LA, He L, Jensen T, Cui L, Gentzsch M, Dokholyan NV, Riordan JR. Regulatory insertion removal restores maturation, stability and function of DeltaF508 CFTR. J Mol Biol. 2010 Aug 13;401(2):194-210. doi: 10.1016/j.jmb.2010.06.019. PMID: 20561529; PMCID: PMC4361937.
  19. Hutt DM, Herman D, Rodrigues AP, Noel S, Pilewski JM, Matteson J, Hoch B, Kellner W, Kelly JW, Schmidt A, Thomas PJ, Matsumura Y, Skach WR, Gentzsch M, Riordan JR, Sorscher EJ, Okiyoneda T, Yates JR 3rd, Lukacs GL, Frizzell RA, Manning G, Gottesfeld JM, Balch WE. Reduced histone deacetylase 7 activity restores function to misfolded CFTR in cystic fibrosis. Nat Chem Biol. 2010 Jan;6(1):25-33. doi: 10.1038/nchembio.275. PMID: 19966789; PMCID: PMC2901172.
John Riordan