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The structure of the Haemophilus influenzae HMW1 pro-piece reveals a structural domain essential for bacterial

Hye-Jeong Yeo1, Takeshi Yokoyama, Katarzyna Walkiewicz

  • 1Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204, USA. hyeo@uh.edu

The Journal of Biological Chemistry
|August 19, 2007
PubMed

Insights

The crystal structure of the HMW1 secretion domain reveals a beta-helix fold, crucial for targeting virulence factors in nontypeable Haemophilus influenzae to outer membrane proteins.

Area of Science:

  • Microbiology
  • Structural Biology
  • Bacterial Pathogenesis

Background:

  • Many Gram-negative bacteria use the two-partner secretion (TPS) pathway for virulence factor export.
  • HMW1 and HMW2 adhesins are key virulence factors in nontypeable Haemophilus influenzae, utilizing the TPS pathway.
  • Targeting of these adhesins to outer membrane proteins (TpsB) is mediated by an N-terminal secretion domain.

Purpose of the Study:

  • To determine the crystal structure of the HMW1 secretion domain (HMW1-PP).
  • To elucidate the structural basis for targeting HMW1 adhesin to its cognate outer membrane translocator (HMW1B).
  • To compare the structure with other TPS secretion domains for conserved features.

Main Methods:

  • X-ray crystallography was used to determine the structure of HMW1-PP at 1.92 Å resolution.
  • Structural analysis and comparison with the Bordetella pertussis FHA secretion domain (Fha30) were performed.

Main Results:

  • The HMW1 secretion domain adopts a right-handed beta-helix fold with 12 parallel coils and an extra-helical domain.
  • Despite limited amino acid homology, HMW1-PP shares structural features with Fha30.
  • These shared features suggest a common structural motif for TpsA secretion domains.

Conclusions:

  • The beta-helix fold of the HMW1 secretion domain is essential for its function in the two-partner secretion pathway.
  • Conserved structural elements across different TpsA secretion domains may underpin specific interactions with cognate TpsB proteins.
  • Understanding these structures can provide insights into the specificity of TpsA-TpsB interactions in bacterial virulence.

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