Biological Assembly 1  

 3D View: Structure | Electron Density | Validation Report

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 47.30 kDa 
• Atom Count: 2489 
• Modelled Residue Count: 320 
• Deposited Residue Count: 421 
• Unique protein chains: 1

5H7V

Structure of full-length extracellular domain of HAI-1 at pH 4.6

• DOI: 10.2210/pdb5H7V/pdb

• Classification: HYDROLASE INHIBITOR
• Organism(s): Homo sapiens
• Expression System: Drosophila melanogaster
• Mutation(s): No 


• Deposited: 2016-11-21 Released: 2017-03-29 
• Deposition Author(s): Liu, M., Huang, M.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 3.82 Å
• R-Value Free: 0.328 
• R-Value Work: 0.253 
• R-Value Observed: 0.256 

Literature

The crystal structure of a multidomain protease inhibitor (HAI-1) reveals the mechanism of its auto-inhibition

Liu, M., Yuan, C., Jensen, J.K., Zhao, B., Jiang, Y., Jiang, L., Huang, M.

(2017) J Biol Chem 292: 8412-8423

• PubMed: 28348076 
• DOI: 10.1074/jbc.M117.779256
• Primary Citation of Related Structures:  
  5H7V


• PubMed Abstract: 
  

Hepatocyte growth factor activator inhibitor 1 (HAI-1) is a membrane-bound multidomain protein essential to the integrity of the basement membrane during placental development and is also important in maintaining postnatal homeostasis in many tissues. HAI-1 is a Kunitz-type serine protease inhibitor, and soluble fragments of HAI-1 with variable lengths have been identified in vivo The full-length extracellular portion of HAI-1 (sHAI-1) shows weaker inhibitory activity toward target proteases than the smaller fragments, suggesting auto-inhibition of HAI-1. However, this possible regulatory mechanism has not yet been evaluated. Here, we solved the crystal structure of sHAI-1 and determined the solution structure by small-angle X-ray scattering. These structural analyses revealed that, despite the presence of long linkers, sHAI-1 exists in a compact conformation in which sHAI-1 active sites in Kunitz domain 1 are sterically blocked by neighboring structural elements. We also found that in the presence of target proteases, sHAI-1 adopts an extended conformation that disables the auto-inhibition effect. Our results also reveal the roles of non-inhibitory domains of this multidomain protein and explain the low activity of the full-length protein. The structural insights gained here improve our understanding of the regulation of HAI-1 inhibitory activities and point to new approaches for better controlling these activities.

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Organizational Affiliation: 

the College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108, China.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Kunitz-type protease inhibitor 1	A	421	Homo sapiens	Mutation(s): 0  Gene Names: SPINT1, HAI1, UNQ223/PRO256
UniProt & NIH Common Fund Data Resources
Find proteins for O43278 (Homo sapiens) Explore O43278  Go to UniProtKB:  O43278
PHAROS:  O43278 GTEx:  ENSG00000166145

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 3.82 Å
• R-Value Free: 0.328 
• R-Value Work: 0.253 
• R-Value Observed: 0.256 
• Space Group: P 4₁ 2₁ 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 95.62	α = 90
b = 95.62	β = 90
c = 124.58	γ = 90

Software Package:

Software Name	Purpose
PHENIX	refinement
PDB_EXTRACT	data extraction
xia2	data reduction
xia2	data scaling
PHENIX	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2016-11-21 
• Released Date: 2017-03-29 
Deposition Author(s): Liu, M., Huang, M.

Revision History  

• Version 1.0: 2017-03-29
  Type: Initial release
  
• Version 1.1: 2017-04-19
  Changes: Database references
• Version 1.2: 2017-05-31
  Changes: Database references