LAP2 binds to BAF⋅DNA complexes: requirement for the LEM domain and modulation by variable regions

AUTOR(ES)

Shumaker, Dale K.

FONTE

Oxford University Press

RESUMO

LAP2 belongs to a family of nuclear membrane proteins sharing a 43 residue LEM domain. All LAP2 isoforms have the same N-terminal ‘constant’ region (LAP2-c), which includes the LEM domain, plus a C-terminal ‘variable’ region. LAP2-c polypeptide inhibits nuclear assembly in Xenopus extracts, and binds in vitro to barrier-to-autointegration factor (BAF), a DNA-bridging protein. We tested 17 Xenopus LAP2-c mutants for nuclear assembly inhibition, and binding to BAF and BAF⋅DNA complexes. LEM domain mutations disrupted all activities tested. Some mutations outside the LEM domain had no effect on binding to BAF, but disrupted activity in Xenopus extracts, suggesting that LAP2-c has an additional unknown function required to inhibit nuclear assembly. Mutagenesis results suggest that BAF changes conformation when complexed with DNA. The binding affinity of LAP2 was higher for BAF⋅DNA complexes than for BAF, suggesting that these interactions are physiologically relevant. Nucleoplasmic domains of Xenopus LAP2 isoforms varied 9-fold in their affinities for BAF, but all isoforms supershifted BAF⋅DNA complexes. We propose that the LEM domain is a core BAF-binding domain that can be modulated by the variable regions of LAP2 isoforms.

Documentos Relacionados

• Solution structure of the constant region of nuclear envelope protein LAP2 reveals two LEM-domain structures: one binds BAF and the other binds DNA
• LAP2α and BAF collaborate to organize the Moloney murine leukemia virus preintegration complex
• Cloning of a cDNA for lamina-associated polypeptide 2 (LAP2) and identification of regions that specify targeting to the nuclear envelope.
• Laparoscopy Compared With Laparotomy for Comprehensive Surgical Staging of Uterine Cancer: Gynecologic Oncology Group Study LAP2
• Protein-DNA complexes: the cost of recognition.