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Side chain and backbone contributions of Phe508 to CFTR folding

Nature Structural & Molecular Biology volume 12, pages 10–16 (2005)Cite this article

Abstract

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), an integral membrane protein, cause cystic fibrosis (CF). The most common CF-causing mutant, deletion of Phe508, fails to properly fold. To elucidate the role Phe508 plays in the folding of CFTR, missense mutations at this position were generated. Only one missense mutation had a pronounced effect on the stability and folding of the isolated domain in vitro. In contrast, many substitutions, including those of charged and bulky residues, disrupted folding of full-length CFTR in cells. Structures of two mutant nucleotide-binding domains (NBDs) reveal only local alterations of the surface near position 508. These results suggest that the peptide backbone plays a role in the proper folding of the domain, whereas the side chain plays a role in defining a surface of NBD1 that potentially interacts with other domains during the maturation of intact CFTR.

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Figure 1: NBD1 folding efficiency as a function of folding temperature.
Figure 2: Structure of NBD1 proteins.
Figure 3: Maturation of full-length CFTR mutants.
Figure 4: ABC transporter structure and CFTR biogenesis.

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Acknowledgements

We thank H. Lewis and M. Kearins for helpful advice regarding production of the two NBD1 crystal forms and members of the Thomas lab and the Structural Biology Lab for helpful suggestions and constructive criticism. This work was supported by grants from the US National Institutes of Health (NIH) (DK49835), the Cystic Fibrosis Foundation (THOMAS01GO) and Welch Foundation (I-1284) to P.J.T. and by a position on the NIH Training Grant, Mechanisms of Drug Action and Disposition (GM07062), awarded to P.H.T.

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Authors and Affiliations

  1. Department of Physiology, The University of Texas Southwestern Medical Center at Dallas, Dallas, 75390, Texas, USA

    Patrick H Thibodeau & Philip J Thomas

  2. Department of Biochemistry, The University of Texas Southwestern Medical Center at Dallas, Dallas, 75390, Texas, USA

    Chad A Brautigam & Mischa Machius

  3. Molecular Biophysics Graduate Program, The University of Texas Southwestern Medical Center at Dallas, Dallas, 75390, Texas, USA

    Patrick H Thibodeau, Mischa Machius & Philip J Thomas

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Correspondence to Philip J Thomas.

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Supplementary Fig. 1

Mutant NBD1 structures and conformations. (PDF 886 kb)

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Thibodeau, P., Brautigam, C., Machius, M. et al. Side chain and backbone contributions of Phe508 to CFTR folding. Nat Struct Mol Biol 12, 10–16 (2005). https://doi.org/10.1038/nsmb881

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