tailieunhanh - Báo cáo khoa học: Secondary structure of lipidated Ras bound to a lipid bilayer

Ras proteins are small guanine nucleotide binding proteins that regulate many cellular processes, including growth control. They undergo distinct post-translational lipid modifications that are required for appropriate targeting to membranes. This, in turn, is critical for Ras biological func-tion. | Secondary structure of lipidated Ras bound to a lipid bilayer Jorn Guldenhaupt1 Yekbun Adiguzel1 Jurgen Kuhlmann2 Herbert Waldmann2 Carsten Kotting1 and Klaus Gerwert1 1 Lehrstuhlfur Biophysik Ruhr-Universitat Bochum Germany 2 Max Planck Institute of Molecular Physiology Dortmund Germany Keywords FTIR GTPases lipid anchor membrane proteins Correspondence K. Gerwert Lehrstuhlfur Biophysik Ruhr-Universitat Bochum Universitatsstr. 150 D-44801 Bochum Germany Fax 49 234 32 14238 Tel 49 234 32 24461 E-mail gerwert@ These authors contributed equally to this work Received 28 August 2008 revised 25 September 2008 accepted 1 October 2008 doi Ras proteins are small guanine nucleotide binding proteins that regulate many cellular processes including growth control. They undergo distinct post-translational lipid modifications that are required for appropriate targeting to membranes. This in turn is critical for Ras biological function. However most in vitro studies have been conducted on nonlipidated truncated forms of Ras proteins. Here for the first time attenuated total reflectance-FTIR studies of lipid-modified membrane-bound N-Ras are performed and compared with nonlipidated truncated Ras in solution. For these studies lipidated N-Ras was prepared by linking a farnesylated and hexadecylated N-Ras lipopeptide to a truncated N-Ras protein residues 1-181 . It was then bound to a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer tethered on an attenuated total reflectance crystal. The structurally sensitive amide I absorbance band in the IR was detected and analysed to determine the secondary structure of the protein. The NMR three-dimensional structure of truncated Ras was used to calibrate the contributions of the different secondary structural elements to the amide I absorbance band of truncated Ras. Using this novel approach the correct decomposition was selected from several possible solutions. The same parameter set was .