title: Structure of the recombinant BPTI/Kunitz-type inhibitor rShPI-1A from the marine invertebrate Stichodactyla helianthus.
abstract: The BPTI/Kunitz-type inhibitor family includes several extremely potent serine protease inhibitors. To date, the inhibitory mechanisms have only been studied for mammalian inhibitors. Here, the first crystal structure of a BPTI/Kunitz-type inhibitor from a marine invertebrate (rShPI-1A) is reported to 2.5 Å resolution. Crystallization of recombinant rShPI-1A required the salt-induced dissociation of a trypsin complex that was previously formed to avoid intrinsic inhibitor aggregates in solution. The rShPI-1A structure is similar to the NMR structure of the molecule purified from the natural source, but allowed the assignment of disulfide-bridge chiralities and the detection of an internal stabilizing water network. A structural comparison with other BPTI/Kunitz-type canonical inhibitors revealed unusual ϕ angles at positions 17 and 30 to be a particular characteristic of the family. A significant clustering of ϕ and ψ angle values in the glycine-rich remote fragment near the secondary binding loop was additionally identified, but its impact on the specificity of rShPI-1A and similar molecules requires further study.
authors.affiliation: Centro de Estudio de Proteínas, Facultad de Biología, Universidad de la Habana, Calle 25 No. 455, Havana 10400, Cuba.
authors.forename: Rossana
authors.initials: R
authors.lastname: García-Fernández
authors.forename: Tirso
authors.initials: T
authors.lastname: Pons
authors.forename: Arne
authors.initials: A
authors.lastname: Meyer
authors.forename: Markus
authors.initials: M
authors.lastname: Perbandt
authors.forename: Yamile
authors.initials: Y
authors.lastname: González-González
authors.forename: Dayrom
authors.initials: D
authors.lastname: Gil
authors.forename: María
authors.initials: M
authors.lastname: de los Angeles Chávez
authors.forename: Christian
authors.initials: C
authors.lastname: Betzel
authors.forename: Lars
authors.initials: L
authors.lastname: Redecke
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D012615:Sea Anemones; D016415:Sequence Alignment; D040681:Structural Homology, Protein; D014360:Trypsin Inhibitor, Kunitz Soybean / Q000737:chemistry*
chemical_list: D011994:Recombinant Proteins; C080476:ShPI proteinase inhibitor; D014360:Trypsin Inhibitor, Kunitz Soybean