Structural mechanism for guanylate-binding proteins (GBPs) targeting by the Shigella E3 ligase IpaH9.8

PLoS Pathog. 2019 Jun 19;15(6):e1007876. doi: 10.1371/journal.ppat.1007876. eCollection 2019 Jun.

Abstract

The guanylate-binding proteins (GBPs) belong to the dynamin superfamily of GTPases and function in cell-autonomous defense against intracellular pathogens. IpaH9.8, an E3 ligase from the pathogenic bacterium Shigella flexneri, ubiquitinates a subset of GBPs and leads to their proteasomal degradation. Here we report the structure of a C-terminally truncated GBP1 in complex with the IpaH9.8 Leucine-rich repeat (LRR) domain. IpaH9.8LRR engages the GTPase domain of GBP1, and differences in the Switch II and α3 helix regions render some GBPs such as GBP3 and GBP7 resistant to IpaH9.8. Comparisons with other IpaH structures uncover interaction hot spots in their LRR domains. The C-terminal region of GBP1 undergoes a large rotation compared to previously determined structures. We further show that the C-terminal farnesylation modification also plays a role in regulating GBP1 conformation. Our results suggest a general mechanism by which the IpaH proteins target their cellular substrates and shed light on the structural dynamics of the GBPs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Molecular Dynamics Simulation*
  • Protein Domains
  • Shigella flexneri / enzymology*
  • Shigella flexneri / genetics
  • Ubiquitin-Protein Ligases / chemistry*
  • Ubiquitin-Protein Ligases / genetics

Substances

  • Bacterial Proteins
  • Ubiquitin-Protein Ligases

Grants and funding

This work was supported by the National Key Research and Development Program of China (2017YFA0505200 and 2016YFC0906000), the National Science Foundation of China (31570735, 31822014), the Clinical Medicine Plus X - Young Scholars Project of Peking University, and the Qidong-SLS Innovation Fund to J.X.; as well as the Basic Science Center Project of NSFC (81788104) and the National Key Research and Development Program of China (2017YFA0505900 and 2016YFA0501500) to F.S. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.