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Identification of a nuclear targeting signal in YopM from Yersinia spp

Rachid Benabdillah1, Luís Jaime Mota, Silke Lützelschwab

  • 1Microbial Pathogenesis Unit, Christian de Duve Institute of Cellular Pathology and Université catholique de Louvain, B1200 Brussels, Belgium.

Microbial Pathogenesis
|March 27, 2004
PubMed

Insights

Yersinia

Area of Science:

  • Microbiology
  • Molecular Biology
  • Cell Biology

Background:

  • Yersinia's YopM protein is a key virulence factor, but its function and cellular localization remain poorly understood.
  • YopM, an acidic leucine-rich repeat (LRR) protein, targets the host cell nucleus without a canonical nuclear localization signal (NLS).

Purpose of the Study:

  • To identify the specific region and residues within YopM responsible for its nuclear import.
  • To confirm the functionality of the identified NLS in mammalian cells and its role in YopM's nuclear localization.

Main Methods:

  • Utilized a yeast-based system to screen for nuclear localization sequences within YopM.
  • Employed HEK293T cell transfection with YopM deletion constructs and site-directed mutagenesis to validate NLS activity in mammalian systems.
  • Constructed EGFP-YopM fusion proteins to assess the functional significance of the identified NLS.

Main Results:

  • The first three leucine-rich repeats (LRR1-3) and the C-terminal 32 residues (YopMC-ter) of YopM function as NLSs in yeast.
  • YopMC-ter directs large recombinant proteins into the nucleus of HEK293T cells, confirming its NLS activity in mammalian cells.
  • Specific residues within YopMC-ter were identified as critical for nuclear targeting, and this NLS was essential for the nuclear localization of an EGFP-YopM fusion protein.

Conclusions:

  • Yersinia's YopM protein possesses a functional NLS within its C-terminal region (YopMC-ter).
  • This NLS is sufficient to direct proteins to the nucleus in both yeast and mammalian cells.
  • The identified NLS is crucial for the nuclear import of YopM, providing insights into its pathogenic mechanisms.

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