The tail domain of lamin Dm₀ binds histones H2A and H2B

In multicellular organisms, the higher order organization of chromatin during interphase and the reassembly of the nuclear envelope during mitosis are thought to involve an interaction between the nuclear lamina and chromatin. The nuclear distribution of lamins and of peripheral chromatin is highly correlated in vivo, and lamins bind specifically to chromatin in vitro. Deletion mutants of Drosophila lamin Dm₀ were expressed to map regions of the protein that are required for its binding to chromosomes. The binding activity requires two regions in the lamin Dm₀ tail domain. The apparent K(d) of binding of the lamin Dm₀ tail domain was found to be approximately 1 μM. Chromatin subfractions were examined to search for possible target molecules for the binding of lamin Dm₀. Isolated polynucleosomes, nucleosomes, histone octamer, histone H2A/H2B dimer, and histones H2A or H2B displaced the binding of lamin Dm₀ tail to chromosomes. This displacement was specific, because polyamines or proteins such as histones H1, H3, or H4 did not displace the binding of the lamin Dm₀ tail to chromosomes. In addition, DNA sequences, including M/SARs, did not interfere with the binding of lamin Dm₀ tail domain to chromosomes. Taken together, these results suggest that the interaction between the tail domain of lamin Dm₀ and histones H2A and H2B may mediate the attachment of the nuclear lamina to chromosomes in vivo.