Lem2 is retained at the nuclear envelope through its interaction with Bqt4 in fission yeast

Genes Cells. 2018 Mar;23(3):122-135. doi: 10.1111/gtc.12557. Epub 2018 Jan 2.


Inner nuclear membrane (INM) proteins are thought to play important roles in modulating nuclear organization and function through their interactions with chromatin. However, these INM proteins share redundant functions in metazoans that pose difficulties for functional studies. The fission yeast Schizosaccharomyces pombe exhibits a relatively small number of INM proteins, and molecular genetic tools are available to separate their redundant functions. In S. pombe, it has been reported that among potentially redundant INM proteins, Lem2 displays a unique genetic interaction with another INM protein, Bqt4, which is involved in anchoring telomeres to the nuclear envelope. Double mutations in the lem2 and bqt4 genes confer synthetic lethality during vegetative growth. Here, we show that Lem2 is retained at the nuclear envelope through its interaction with Bqt4, as the loss of Bqt4 results in the exclusive accumulation of Lem2 to the spindle pole body (SPB). An N-terminal nucleoplasmic region of Lem2 bears affinity to both Bqt4 and the SPB in a competitive manner. In contrast, the synthetic lethality of the lem2 bqt4 double mutant is suppressed by the C-terminal region of Lem2. These results indicate that the N-terminal and C-terminal domains of Lem2 show independent functions with respect to Bqt4.

Keywords: Schizosaccharomyces pombe; Bqt4; DNA binding; Lem2; Man1; nuclear membrane; spindle pole body.

MeSH terms

  • DNA, Fungal / genetics
  • DNA, Fungal / metabolism
  • DNA-Binding Proteins / metabolism*
  • Membrane Proteins / metabolism*
  • Nuclear Envelope / genetics
  • Nuclear Envelope / metabolism*
  • Nuclear Proteins / metabolism*
  • Protein Interaction Domains and Motifs
  • Schizosaccharomyces / growth & development
  • Schizosaccharomyces / metabolism*
  • Schizosaccharomyces pombe Proteins / metabolism*
  • Telomere / genetics
  • Telomere / metabolism*


  • Bqt4 protein, S pombe
  • DNA, Fungal
  • DNA-Binding Proteins
  • Lem2 protein, S pombe
  • Membrane Proteins
  • Nuclear Proteins
  • Schizosaccharomyces pombe Proteins