Characterization of the structure and function of Escherichia coli DegQ as a representative of the DegQ-like proteases of bacterial HtrA family proteins

Xiao Chen Bai, Xi Jiang Pan, Xiao Jing Wang, Yun Ying Ye, Lei Fu Chang, Dong Leng, Jianlin Lei, Sen Fang Sui

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HtrA family proteins play a central role in protein quality control in the bacterial periplasmic space. DegQ-like proteases, a group of bacterial HtrA proteins, are characterized by a short LA loop as compared with DegP-like proteases, and are found in many bacterial species. As a representative of the DegQ-like proteases, we report that Escherichia coli DegQ exists in vivo primarily as a trimer (substrate-free) or dodecamer (substrate-containing). Biochemical analysis of DegQ dodecamers revealed that the major copurified protein substrate is OmpA. Importantly, wild-type DegQ exhibited a much lower proteolytic activity, and thus higher chaperone-like activity, than DegP. Furthermore, using cryo-electron microscopy we determined high-resolution structures of DegQ 12- and 24-mers in the presence of substrate, thus revealing the structural mechanism by which DegQ moderates its proteolytic activity.

Original languageEnglish (US)
Pages (from-to)1328-1337
Number of pages10
Issue number9
Publication statusPublished - Sep 7 2011


ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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