tailieunhanh - Báo cáo khoa học: Characterization of SCP-2 from Euphorbia lagascae reveals that a single Leu/Met exchange enhances sterol transfer activity

Sterol carrier protein-2 (SCP-2) is a small intracellular basic protein domain implicated in peroxisomalb-oxidation. We extend our knowledge of plant SCP-2 by characterizing SCP-2 fromEuphorbia lagascae. This pro-tein consists of 122 amino acids including a PTS1 peroxisomal targeting signal. | ỊFEBS Journal Characterization of SCP-2 from Euphorbia lagascae reveals that a single Leu Met exchange enhances sterol transfer activity Lenita Viitanen1 Matts Nylund1 D. Magnus Eklund2 Christina Alm2 Ann-Katrin Eriksson2 Jessica Tuuf1 Tiina A. Salminen1 Peter Mattjus1 and Johan Edqvist2 3 1 Department of Biochemistry and Pharmacy Abo Akademi University Turku Finland 2 Department of Plant Biology and Forest Genetics Swedish University of AgriculturalSciences Uppsala Sweden 3 IFM-Biology Linkoping University Sweden Keywords b-oxidation lipid transfer protein peroxisome sterol sterolcarrier protein-2 Correspondence J. Edqvist Department of Plant Biology and Forest Genetics Swedish University of AgriculturalSciences Box 7080 750 07 Uppsala Sweden Fax 46 18 673389 Tel 46 18 673242 E-mail These authors contributed equally to this work Received 25 August 2006 revised 3 October 2006 accepted 23 October 2006 doi Sterol carrier protein-2 SCP-2 is a small intracellular basic protein domain implicated in peroxisomal b-oxidation. We extend our knowledge of plant SCP-2 by characterizing SCP-2 from Euphorbia lagascae. This protein consists of 122 amino acids including a PTS1 peroxisomal targeting signal. It has a molecular mass of kDa and a pI of . It shares 67 identity and 84 similarity with SCP-2 from Arabidopsis thaliana. Proteo-mic analysis revealed that E. lagascae SCP-2 accumulates in the endosperm during seed germination. It showed in vitro transfer activity of BODIPY-phosphatidylcholine BODIPY-PC . The transfer of BODIPY-PC was almost completely inhibited after addition of phosphatidylinositol palmitic acid stearoyl-CoA and vernolic acid whereas sterols only had a very marginal inhibitory effect. We used protein modelling and site-directed mutagenesis to investigate why the BODIPY-PC transfer mediated by E. lagascae SCP-2 is not sensitive to sterols whereas the transfer mediated by A. thaliana SCP-2 shows