ABCMdb

PMID: 22352759

Norimatsu Y, Ivetac A, Alexander C, Kirkham J, O'Donnell N, Dawson DC, Sansom MS
Cystic fibrosis transmembrane conductance regulator: a molecular model defines the architecture of the anion conduction path and locates a "bottleneck" in the pore.
Biochemistry. 2012 Mar 20;51(11):2199-212. Epub 2012 Mar 7., [PubMed]

Sentences

No. Mutations Sentence Comment

177 ABCC7 p.Ile1131Cys It is noteworthy that in several cases (e.g., I1131C) application of MTSES- , which carries a net negative charge, led to an increase in macroscopic conductance. Login to comment 218 ABCC7 p.Phe337Cys The dagger denotes that F337C was previously reported by our group to be unreactive toward MTSET+ and MTSES- . Login to comment 259 ABCC7 p.Thr1142Cys ABCC7 p.Met348Cys Chen et al.41 observed cross-linking of M348C and T1142C by M5M and M8M but not M17M. Login to comment 262 ABCC7 p.Thr1142Cys ABCC7 p.Met348Cys The two ends of M17M are predicted by the MD simulation to come close to each other in free solution, forming a folded structure, theoretically allowing cross-linking of engineered cysteines such as M348C and T1142C. Login to comment 267 ABCC7 p.Thr351Cys ABCC7 p.Leu1143Cys Chen et al.41 did not observe cross-linking of T351C and L1143C with any of the three cross-linking agents. Login to comment 333 ABCC7 p.Ser341Cys Neither of the channel-impermeant regents, MTSET+ or MTSES- , reacted with S341C when each was applied from the extracelluar side. Login to comment 338 ABCC7 p.Phe337Cys Recently, however, we used temperature increases from 22 to 37 °C to effect substantial changes in the conformation of the outer vestibule of the CFTR pore that were evident from markedly increased rates of reaction of MTSES- with cysteines substituted at positions 334 and 336-338 at 37 °C.62 In the case of F337C CFTR, a cysteine that was unreactive toward externally applied MTSES- at 22 °C was highly reactive at 37 °C. Despite these substantial changes in conformation, however, the position of the size selectivity barrier was unchanged. Login to comment 345 ABCC7 p.Arg352Cys ABCC7 p.Arg352Cys They found that R352C CFTR exhibited unstable gating and reduced current excursions reminiscent of the subconductance states reported by Cui et al.11 Modification of R352C CFTR by either MTSET+ or MTSEA+ restored the full conductance state and appeared to stabilize the gating pattern. Login to comment 367 ABCC7 p.Thr338Cys ABCC7 p.Thr338Cys ABCC7 p.Arg334Asp Similarly, while both extracellular MTSET+ and MTSES- react with a cysteine at position 338, the ratio of the rates of reaction (kMTSET +/kMTSES -) of these oppositely charged reagents was <1.0 for T338C/wt CFTR and >1.0 for T338C/ R334D CFTR as expected if the charge at this position makes a major contribution to the electrostatic potential at the outer rim of the bottleneck.40 Studies of the impact of covalent and noncovalent modifications at position 338 also argue that the electrostatic potential at this site, just on the outward-facing lip of the bottleneck, is critical for anion conduction. Login to comment