The objectives of this project are to systematically study protein mobility with NMR and relate mobility to amino acid sequences and to protein function. The proposal has three major aspects. (i) A descriptive part is focused on characterizing structure and mobility of three protein systems: the methyl transfer protein ada and its complex with DNA, the histone acetyl transfer (HAT) domain from the tetrahymena protein p55, in the complex with CoA, and the CD2/CD58 receptor/counter-receptor pair. This aspect also contains an effort to develop and apply methods for deriving pictorial representations of internal motions, based on spectral density mapping, as well as new experimental approaches for deriving mobility data from relaxation experiments. (ii) A second aspect is to develop an understanding of the factors that make certain protein regions mobile or rigid. This will be pursued with site directed mutagenesis in vitro, and with computer simulations. (iii) The third aspect is to investigate whether and why protein mobility might be important for protein recognition function. This will be pursued with experimental measurements of protein interactions and free energy perturbation calculations of wild-type and mutant proteins.
Most biological processes are controlled by interaction of proteins with other macromolecules or smaller biologically important molecules. The specific recognition of the correct partners is governed by complementary surface structures. However, surfaces of proteins have been found to be generally quite mobile. This research is focused on describing and understanding the importance and implications of mobility for protein interactions. The three systems on which research will be carried out are from the fields of DNA repair, transcriptional regulation and immune cell activation. The results will shed light on basic mechanisms of biological function.
