Solution structure and backbone dynamics of streptopain: Insight into diverse substrate specificity

Chih Chieh Wang, Hsiang Chee Houng, Chun Liang Chen, Pei Ju Wang, Chih Feng Kuo, Yee Shin Lin, Jiunn Jong Wu, Ming T. Lin, Ching Chuan Liu, Wenya Huang, Woei Jer Chuang

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14 Citations (Scopus)


Streptococcal pyrogenic exotoxin B (SPE B) is a cysteine protease expressed by Streptococcus pyogenes. The D9N, G163S, G163S/A172S, and G239D mutant proteins were expressed to study the effect of the allelic variants on their protease activity. In contrast to other mutants, the G239D mutant was ∼12-fold less active. The Gly-239 residue is located within the C-terminal S230-G239 region, which cannot be observed in the x-ray structure. The three-dimensional structure and backbone dynamics of the 28-kDa mature SPE B (mSPE B) were determined. Unlike the x-ray structure of the 40-kDa zymogen SPE B (proSPE B), we observed the interactions between the C-terminal loop and the active site residues in mSPE B. The structural differences between mSPE B and proSPE B were the conformation of the C-terminal loop and the orientation of the catalytic His-195 residue, suggesting that activation and inactivation of SPE B is involved in the His-195 side-chain rotation. Dynamics analysis ofmSPEBand themSPEB/inhibitor complexes showed that the catalytic and C-terminal loops were the most flexible regions with low order parameter values of 0.5 to 0.8 and exhibited the motion on the ps/ns timescale. These findings suggest that the flexible C-terminal loop of SPE B may play an important role in controlling the substrate binding, resulting in its broad substrate specificity.

Original languageEnglish
Pages (from-to)10957-10967
Number of pages11
JournalJournal of Biological Chemistry
Issue number16
Publication statusPublished - 2009 Apr 17

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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