Structural determinants of specificity and antagonistic Ca2+ and Zn2+ regulation of peptidase activity in human KLK8/neuropsin

ABSTRACT: Human KLK8/neuropsin, a kallikrein-related serine peptidase, is mostly expressed in skin and hippocampus, where it regulates memory formation by synaptic remodeling. Recombinantly expressed KLK8 revealed a good accordance two substrate profiling methods: positional scanning with fluorogenic tetrapeptides and a novel version of the proteomic PICS approach. Besides a strong preference for Arg in the P1 position, the enzyme favors Thr in P4, basic P3 residues, aliphatic P2, small P1′ and aliphatic P2′ residues. Enzyme kinetic studies with synthesized substrates showed stimulatory and inhibitory effects of Ca2+ and Zn2+, respectively, which are important for physiological functions. Two crystal structures of KLK8 with the active site inhibitor leupeptin explain the subsite specificity and display Ca2+ bound to the 75-loop, which is unique among the KLKs. The mutants D70K and H99A confirmed the antagonistic role of the cation binding sites, for which a comparison with the murine apo-KLK8 structure clarified further mechanistic details. Molecular docking and dynamics calculations provided insights in substrate binding and the dual regulation by Ca2+ and Zn2+, involving an allosteric surface loop network.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Escherichia Coli

SUBMITTER: Oliver Schilling  

LAB HEAD: Oliver Schilling

PROVIDER: PXD006884 | Pride | 2018-10-17

REPOSITORIES: Pride