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Essential calcium-binding cluster of Leptospira LipL32 protein for inflammatory responses through the Toll-like

Yueh-Yu Lo1, Shen-Hsing Hsu, Yi-Ching Ko

  • 1Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, Hsin Chu 30013, Taiwan.

The Journal of Biological Chemistry
|March 15, 2013
PubMed

Insights

The calcium-binding cluster in Leptospira LipL32 protein is crucial for its interaction with Toll-like receptor 2 (TLR2). This interaction triggers inflammatory responses in human kidney cells.

Area of Science:

  • Microbiology
  • Immunology
  • Structural Biology

Background:

  • Leptospirosis is a widespread zoonotic disease caused by pathogenic Leptospira.
  • LipL32, a major outer membrane lipoprotein of Leptospira, possesses an atypical poly(Asp) motif and is implicated in host-pathogen interactions.

Purpose of the Study:

  • To investigate the role of the calcium (Ca2+)-binding cluster in LipL32 for its interaction with Toll-like receptor 2 (TLR2).
  • To determine the impact of this interaction on inflammatory responses in human kidney cells.

Main Methods:

  • Site-directed mutagenesis was used to alter Ca2+-binding residues in LipL32.
  • Binding assays and atomic force microscopy assessed LipL32 mutant binding to TLR2.
  • Analysis of TLR2 pathway intermediates (hCXCL8/IL-8, hCCL2/MCP-1, hMMP7, hTNF-α) measured inflammatory responses.

Main Results:

  • Mutations in the Ca2+-binding cluster disrupted the structural integrity of LipL32.
  • LipL32 mutants exhibited significantly reduced binding capability to TLR2.
  • The inflammatory responses induced by LipL32 variants were diminished.

Conclusions:

  • The Ca2+-binding cluster of LipL32 is essential for maintaining its conformation.
  • Proper LipL32 conformation, facilitated by the Ca2+-binding cluster, is necessary for effective association with TLR2.
  • This association is critical for eliciting inflammatory responses in human renal cells via the TLR2 pathway.

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