The Haemophilus influenzae Hia autotransporter contains an unusually short trimeric translocator domain.

Journal Article (Journal Article)

Gram-negative bacterial autotransporter proteins are a growing group of virulence factors that are characterized by their ability to cross the outer membrane without the help of accessory proteins. A conserved C-terminal beta-domain is critical for targeting of autotransporters to the outer membrane and for translocation of the N-terminal "passenger" domain to the bacterial surface. We have demonstrated previously that the Haemophilus influenzae Hia adhesin belongs to the autotransporter family, with translocator activity residing in the C-terminal 319 residues. To gain further insight into the mechanism of autotransporter protein translocation, we performed a structure-function analysis on Hia. In initial experiments, we generated a series of in-frame deletions and a set of chimeric proteins containing varying regions of the Hia C terminus fused to a heterologous passenger domain and discovered that the final 76 residues of Hia are both necessary and sufficient for translocation. Analysis by flow cytometry revealed that the region N-terminal to this shortened translocator domain is surface localized, further suggesting that this region is not involved in beta-barrel formation or in translocation of the passenger domain. Western analysis demonstrated that the translocation-competent regions of the C terminus migrated at masses consistent with trimers, suggesting that the Hia C terminus oligomerizes. Furthermore, fusion proteins containing a heterologous passenger domain demonstrated that similarly small C-terminal regions of Yersinia sp. YadA and Neisseria meningitidis NhhA are translocation-competent. These data provide experimental support for a unique subclass of autotransporters characterized by a short trimeric translocator domain.

Full Text

Duke Authors

Cited Authors

  • Surana, NK; Cutter, D; Barenkamp, SJ; St Geme, JW

Published Date

  • April 9, 2004

Published In

Volume / Issue

  • 279 / 15

Start / End Page

  • 14679 - 14685

PubMed ID

  • 14726537

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.M311496200


  • eng

Conference Location

  • United States