Open AccessStructure of the recombinant BPTI/Kunitz‐type inhibitor r ShPI‐1A from the marine invertebrate Stichodactyla helianthus
Author(s) -
GarcíaFernández Rossana,
Pons Tirso,
Meyer Arne,
Perbandt Markus,
GonzálezGonzález Yamile,
Gil Dayrom,
de los Angeles Chávez María,
Betzel Christian,
Redecke Lars
Publication year - 2012
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
ISSN - 1744-3091
DOI - 10.1107/s1744309112039085
Subject(s) - recombinant dna , marine invertebrates , biology , botany , biochemistry , ecology , gene
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 ( r ShPI‐1A) is reported to 2.5 Å resolution. Crystallization of recombinant r ShPI‐1A required the salt‐induced dissociation of a trypsin complex that was previously formed to avoid intrinsic inhibitor aggregates in solution. The r ShPI‐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 r ShPI‐1A and similar molecules requires further study.