Crystallization of a nonclassical Kazal-type Carcinoscorpius rotundicauda serine protease inhibitor, CrSPI-1, complexed with subtilisin

Shenoy Rajesh Tulsidas, Saravanan Thangamani, Bow Ho, J. Sivaraman, Jeak Ling Ding

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Serine proteases play a major role in host-pathogen interactions. The innate immune system is known to respond to invading pathogens in a nonspecific manner. The serine protease cascade is an essential component of the innate immune system of the horseshoe crab. The serine protease inhibitor CrSPI isoform 1 (CrSPI-1), a unique nonclassical Kazal-type inhibitor of molecular weight 9.3 kDa, was identified from the hepatopancreas of the horseshoe crab Carcinoscorpius rotundicauda. It potently inhibits subtilisin and constitutes a powerful innate immune defence against invading microbes. Here, the cloning, expression, purification and cocrystallization of CrSPI-1 with subtilisin are reported. The crystals diffracted to 2.6 Å resolution and belonged to space group P21, with unit-cell parameters a = 73.8, b = 65.0, c = 111.9 Å, Β = 95.4°. The Matthews coefficient (V M = 2.64 Å3 Da-1, corresponding to 53% solvent content) and analysis of the preliminary structure solution indicated the presence of one heterotrimer (1:2 ratio of CrSPI-1:subtilisin) and one free subtilisin molecule in the asymmetric unit.

Original languageEnglish (US)
Pages (from-to)533-535
Number of pages3
JournalActa Crystallographica Section F: Structural Biology and Crystallization Communications
Volume65
Issue number5
DOIs
StatePublished - Jun 23 2009

Keywords

  • CrSPI
  • Horseshoe crab
  • Host-pathogen interaction
  • Immune defence
  • Kazal-type serine protease inhibitors
  • Serine proteases

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Genetics
  • Condensed Matter Physics

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