Book of Abstracts: Albany 2011
June 14-18 2011
©Adenine Press (2010)
The Solution and Binding Behavior of the Intrinsically Disordered FG Nups Determined by in cell NMR
The nuclear pore complex (NPC) mediates all transport between the nucleus and cytoplasm. The channel of the NPC is lined with “FG Nups”, a family of intrinsically disordered proteins characterized by phenylalanine-glycine repeat motifs. FG nups form the exquisitely selective filter of the NPC; nonbinding proteins are excluded while the binding of transport factors to the FG nups facilitates their passage through the NPC. Like other intrinsically disordered proteins, the FG nups appear to be very sensitive to their environment, showing vastly different behavior in different experimental conditions; in vitro, the observed behavior of the FG varies from rigid gels to flexible random coil polymers. We used stint-NMR to protein behavior of a model FG not within the living cellular environment. In a stint-NMR experiment,NMR observations are directed performed on bacteria, in vivo co expressing an isotopically labeled protein and an unlabeled binding partner. We found that the solution state of the FG nups within living cells is disordered, while NMR spectra significantly change in vitro buffers, presumably from numerous intra- or inter-molecular contacts. Moreover, the binding interface between transport factors in the FG nups differs considerably between solution and cellular conditions. Thus a key determinant to FG nups behavior is the local environment. These results indicate that the proper behavior of the FG naps is dependent on the normal cellular milieu, and is not necessarily represented in vitro; our findings have important implications for the various current models regarding the molecular mechanisms of nuclear cytoplasmic transport and for behavior are weak cellular interactions generally.
Supported by A Charles Revson postdoctoral fellowship, NIH grans GM067854, GM071329 (MR), GM66354 (DC)
Loren E. Hough1
1Laboratory of Cellular and Structural Biology, Rockefeller University