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Crystal structure of a two-domain fragment of hepatocyte growth factor activator inhibitor-1

DOI: 10.1074/jbc.M115.707240 DOI Help

Authors: Zebin Hong (Aarhus University) , Laura De Meulemeester (Aarhus University) , Annemarie Jacobi (Aarhus University) , Jan Skov Pedersen (Aarhus University) , J. Preben Morth (University of Oslo) , Peter A. Andreasen (Aarhus University) , Jan K. Jensen (Aarhus University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Biological Chemistry , VOL 291 , PAGES 14340 - 14355

State: Published (Approved)
Published: July 2016
Diamond Proposal Number(s): 9107

Open Access Open Access

Abstract: Hepatocyte growth factor activator inhibitor-1 (HAI-1) is a type I transmembrane protein and inhibitor of several serine proteases, including hepatocyte growth factor activator and matriptase. The protein is essential for development as knock-out mice die in utero due to placental defects caused by misregulated extracellular proteolysis. HAI-1 contains two Kunitz-type inhibitor domains (Kunitz), which are generally thought of as a functionally self-contained protease inhibitor unit. This is not the case for HAI-1, where our results reveal how interdomain interactions have evolved to stimulate the inhibitory activity of an integrated Kunitz. Here we present an x-ray crystal structure of an HAI-1 fragment covering the internal domain and Kunitz-1. The structure reveals not only that the previously uncharacterized internal domain is a member of the polycystic kidney disease domain family but also how the two domains engage in interdomain interactions. Supported by solution small angle x-ray scattering and a combination of site-directed mutagenesis and functional assays, we show that interdomain interactions not only stabilize the fold of the internal domain but also stimulate the inhibitory activity of Kunitz-1. By completing our structural characterization of the previously unknown N-terminal region of HAI-1, we provide new insight into the interplay between tertiary structure and the inhibitory activity of a multidomain protease inhibitor. We propose a previously unseen mechanism by which the association of an auxiliary domain stimulates the inhibitory activity of a Kunitz-type inhibitor (i.e. the first structure of an intramolecular interaction between a Kunitz and another domain).

Journal Keywords: cell surface protein; inhibition mechanism; protease inhibitor; protein-protein interaction; tertiary structure; multidomain protein

Diamond Keywords: Kidney Disease

Subject Areas: Biology and Bio-materials, Chemistry

Instruments: I02-Macromolecular Crystallography

Added On: 24/04/2017 14:02


Discipline Tags:

Non-Communicable Diseases Health & Wellbeing Biochemistry Chemistry Structural biology Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)