title: Crystallization and preliminary X-ray crystallographic analysis of a highly specific serpin from the beetle Tenebrio molitor.
abstract: The Toll signalling pathway, which is crucial for innate immunity, is transduced in insect haemolymph via a proteolytic cascade consisting of three serine proteases. The proteolytic cascade is downregulated by a specific serine protease inhibitor (serpin). Recently, the serpin SPN48 was found to show an unusual specific reactivity towards the terminal serine protease, Spätzle-processing enzyme, in the beetle Tenebrio molitor. In this study, the mature form of SPN48 was overexpressed in Escherichia coli and purified. The purified SPN48 protein was crystallized using 14% polyethylene glycol 8000 and 0.1 M 2-(N-morpholino)ethanesulfonic acid pH 6.0 as the precipitant. The crystals diffracted X-rays to 2.1 A resolution and were suitable for structure determination. The crystals belonged to space group P2(1). The crystal structure will provide information regarding how SPN48 achieves its unusual specificity for its target protease.
authors.affiliation: College of Pharmacy and Research Institute for Drug Development, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-735, Republic of Korea.
authors.forename: Sun Hee
authors.initials: SH
authors.lastname: Park
authors.forename: Shunfu
authors.initials: S
authors.lastname: Piao
authors.forename: Hyun Mi
authors.initials: HM
authors.lastname: Kwon
authors.forename: Eun Hye
authors.initials: EH
authors.lastname: Kim
authors.forename: Bok Luel
authors.initials: BL
authors.lastname: Lee
authors.forename: Nam Chul
authors.initials: NC
authors.lastname: Ha
mesh_terms: D000818:Animals; D018360:Crystallography, X-Ray; D019476:Insect Proteins / Q000737:chemistry*; D015843:Serpins / Q000737:chemistry*; D013712:Tenebrio / Q000737:chemistry*
chemical_list: D019476:Insect Proteins; D015843:Serpins