tailieunhanh - Báo cáo khoa học: Insights into the structure of plant a-type phospholipase D Susanne Stumpe, Stephan Konig and Renate Ulbrich-Hofmann ¨

Phospholipases D play an important role in the regulation of cellular pro-cesses in plants and mammals. Moreover, they are an essential tool in the synthesis of phospholipids and phospholipid analogs. Knowledge of phos-pholipase D structures, however, is widely restricted to sequence data. | ễFEBS Journal Insights into the structure of plant a-type phospholipase D Susanne Stumpe Stephan Konig and Renate Ulbrich-Hofmann Martin-Luther University Halle-Wittenberg Institute of Biochemistry and Biotechnology Halle Saale Germany Keywords calcium binding phospholipase D smallangle X-ray scattering stability structure Correspondence R. Ulbrich-Hofmann Martin-Luther University Halle-Wittenberg Institute of Biochemistry and Biotechnology Kurt-Mothes-Str. 3 06120 Halle Saale Germany Fax 49 345 5527303 Tel 49 345 5524864 E-mail Received 29 December 2006 revised 23 February 2007 accepted 20 March 2007 doi Phospholipases D play an important role in the regulation of cellular processes in plants and mammals. Moreover they are an essential tool in the synthesis of phospholipids and phospholipid analogs. Knowledge of phospholipase D structures however is widely restricted to sequence data. The only known tertiary structure of a microbial phospholipase D cannot be generalized to eukaryotic phospholipases D. In this study the isoenzyme form of phospholipase D from white cabbage PLDa2 which is the most widely used plant phospholipase D in biocatalytic applications has been characterized by small-angle X-ray scattering UV-absorption CD and fluorescence spectroscopy to yield the first insights into its secondary and tertiary structure. The structural model derived from small-angle X-ray scattering measurements reveals a barrel-shaped monomer with loosely structured tops. The far-UV CD-spectroscopic data indicate the presence of a-helical as well as b-structural elements with the latter being dominant. The fluorescence and near-UV CD spectra point to tight packing of the aromatic residues in the core of the protein. From the near-UV CD signals and activity data as a function of the calcium ion concentration two binding events characterized by dissociation constants in the ranges of mM and .