J Michael Sauder - Impact of the deltaF508 mutation in first nucleotide-binding domain of human cystic fibrosis transmembrane conductance regulator on domain folding and structure

Version 1

      Publication Details (including relevant citation   information):

      J Biol Chem (2005) 280: 1346-1353.

      Lewis HA, Zhao X, Wang C, Sauder JM, Rooney I, Noland BW, Lorimer   D, Kearins MC, Conners K, Condon B, Maloney PC, Guggino WB, Hunt   JF, Emtage S

      Abstract:

      Cystic fibrosis is caused by defects in the cystic fibrosis    transmembrane conductance regulator (CFTR), commonly the deletion   of  residue Phe-508 (DeltaF508) in the first   nucleotide-binding domain  (NBD1), which results in a severe   reduction in the population of  functional channels at the   epithelial cell surface. Previous studies  employing   incomplete NBD1 domains have attributed this to aberrant    folding of DeltaF508 NBD1. We report structural and biophysical   studies  on complete human NBD1 domains, which fail to   demonstrate significant  changes of in vitro stability or   folding kinetics in the presence or  absence of the   DeltaF508 mutation. Crystal structures show minimal  changes   in protein conformation but substantial changes in local   surface  topography at the site of the mutation, which is   located in the region  of NBD1 believed to interact with the   first membrane spanning domain of  CFTR. These results raise   the possibility that the primary effect of  DeltaF508 is a   disruption of proper interdomain interactions at this  site   in CFTR rather than interference with the folding of NBD1.    Interestingly, increases in the stability of NBD1 constructs   are  observed upon introduction of second-site mutations   that suppress the  trafficking defect caused by the   DeltaF508 mutation, suggesting that  these suppressors might   function indirectly by improving the folding  efficiency of   NBD1 in the context of the full-length protein. The human    NBD1 structures also solidify the understanding of CFTR   regulation by  showing that its two protein segments that   can be phosphorylated both  adopt multiple conformations   that modulate access to the ATPase active  site and   functional interdomain interfaces.

      Address (URL): http://www.jbc.org/content/280/2/1346.long