Sidi Abdellahi Ould M'hamed Ould, Babah Khaled Ould, Brimer Nicole, Nominé Yves, Romier Christophe, Kieffer Bruno, Pol Scott Vande, Travé Gilles, Zanier Katia
Ecole Supérieure de Biotechnologie de Strasbourg, UMR 7242, Boulevard Sébastien Brant, BP 10413, 67412 Illkirch, France.
Protein Expr Purif. 2011 Nov;80(1):8-16. doi: 10.1016/j.pep.2011.06.013. Epub 2011 Jul 14.
E6 is a small oncoprotein involved in tumorigenesis induced by papillomaviruses (PVs). E6 often recognizes its cellular targets by binding to short motifs presenting the consensus LXXLL. E6 proteins have long resisted structural analysis. We found that bovine papillomavirus type 1 (BPV1) E6 binds the N-terminal LXXLL motif of the cellular protein paxillin with significantly higher affinity as compared to other E6/peptide interactions. Although recombinant BPV1 E6 was poorly soluble in the free state, provision of the paxillin LXXLL peptide during BPV1 E6 biosynthesis greatly enhanced the protein's solubility. Expression of BPV1 E6/LXXLL peptide complexes was carried out in bacteria in the form of triple fusion constructs comprising, from N- to C-terminus, the soluble carrier protein maltose binding protein (MBP), the LXXLL motif and the E6 protein. A TEV protease cleavage site was placed either between MBP and LXXLL motif or between LXXLL motif and E6. These constructs allowed us to produce highly concentrated samples of BPV1 E6, either covalently fused to the C-terminus of the LXXLL motif (intra-molecular complex) or non-covalently bound to it (inter-molecular complex). Heteronuclear NMR measurements were performed and showed that the E6 protein was folded with similar conformations in both covalent and non-covalent complexes. These data open the way to novel structural and functional studies of the BPV1 E6 in complex with its preferential target motif.
E6是一种参与乳头瘤病毒(PV)诱导肿瘤发生的小癌蛋白。E6通常通过与呈现共有序列LXXLL的短基序结合来识别其细胞靶点。E6蛋白长期以来一直难以进行结构分析。我们发现,与其他E6/肽相互作用相比,1型牛乳头瘤病毒(BPV1)E6与细胞蛋白桩蛋白的N端LXXLL基序结合的亲和力显著更高。尽管重组BPV1 E6在游离状态下溶解性很差,但在BPV1 E6生物合成过程中提供桩蛋白LXXLL肽可大大提高该蛋白的溶解性。BPV1 E6/LXXLL肽复合物以三聚体融合构建体的形式在细菌中表达,从N端到C端包括可溶性载体蛋白麦芽糖结合蛋白(MBP)、LXXLL基序和E6蛋白。TEV蛋白酶切割位点位于MBP与LXXLL基序之间或LXXLL基序与E6之间。这些构建体使我们能够制备高度浓缩的BPV1 E6样品,要么与LXXLL基序的C端共价融合(分子内复合物),要么与其非共价结合(分子间复合物)。进行了异核核磁共振测量,结果表明E6蛋白在共价和非共价复合物中的折叠构象相似。这些数据为对与优先靶基序结合的BPV1 E6进行新的结构和功能研究开辟了道路。