Porciero Sophie, Receveur-Bréchot Véronique, Mori Kazushige, Franzetti Bruno, Roussel Alain
Architecture et Fonction des Macromolécules Biologiques, UMR 6098 CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2005 Feb 1;61(Pt 2):239-42. doi: 10.1107/S1744309105001910.
The deblocking aminopeptidase (DAP) of Pyrococcus horikoshii is a hyperthermophilic exoprotease that cleaves the N-terminal amino acid of peptide substrates with a putative deblocking activity for acylated peptides. DAP has been found to be homologous to a tetrahedral aminopeptidase from the halophilic Haloarcula marismortui. The latter enzyme is a dodecameric complex and has been revealed to be a self-compartmentalized protease whose central cavity harbouring the catalytic site is accessible through several channels of different size, unlike all other known proteolytic complexes. Three paralogues of DAP have been identified in P. horikoshii, with about 40% identity between them. Each of them has been overexpressed in Escherichia coli, purified and crystallized in the native and selenomethionine-substituted states. The results indicate that they form two kinds of assemblies, of 12 and of 24 subunits, with a molecular weight of approximately 400 and approximately 800 kDa, respectively. Crystals of the different variants of DAP and in their different oligomeric states diffract up to a resolution of 3 A.
嗜热栖热菌的去封闭氨肽酶（DAP）是一种超嗜热外切蛋白酶，可切割肽底物的N端氨基酸，对酰化肽具有假定的去封闭活性。已发现DAP与嗜盐嗜盐碱杆菌的一种四面体氨肽酶同源。后一种酶是一种十二聚体复合物，已被揭示为一种自分隔蛋白酶，其容纳催化位点的中央腔可通过几个不同大小的通道进入，这与所有其他已知的蛋白水解复合物不同。在嗜热栖热菌中已鉴定出DAP的三个旁系同源物，它们之间的同一性约为40%。它们各自在大肠杆菌中过表达、纯化，并在天然状态和硒代甲硫氨酸取代状态下结晶。结果表明，它们形成了两种组装体，分别由12个和24个亚基组成，分子量分别约为400 kDa和约800 kDa。DAP不同变体及其不同寡聚状态的晶体衍射分辨率高达3 Å。
