Goldberg M, Harel A, Brandeis M, Rechsteiner T, Richmond T J, Weiss A M, Gruenbaum Y
Department of Genetics, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Proc Natl Acad Sci U S A. 1999 Mar 16;96(6):2852-7. doi: 10.1073/pnas.96.6.2852.
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 Kd of binding of the lamin Dm0 tail domain was found to be approximately 1 microM. 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.
在多细胞生物中，间期染色质的高级组织形式以及有丝分裂期间核膜的重新组装被认为涉及核纤层与染色质之间的相互作用。在体内，核纤层蛋白和外周染色质的核分布高度相关，并且核纤层蛋白在体外能特异性结合染色质。通过表达果蝇核纤层蛋白Dm0的缺失突变体来定位该蛋白与染色体结合所需的区域。结合活性需要核纤层蛋白Dm0尾部结构域中的两个区域。发现核纤层蛋白Dm0尾部结构域结合的表观解离常数约为1微摩尔。检查染色质亚组分以寻找核纤层蛋白Dm0结合的可能靶分子。分离的多核小体、核小体、组蛋白八聚体、组蛋白H2A/H2B二聚体以及组蛋白H2A或H2B会取代核纤层蛋白Dm0尾部与染色体的结合。这种取代是特异性的，因为多胺或诸如组蛋白H1、H3或H4等蛋白质不会取代核纤层蛋白Dm0尾部与染色体的结合。此外，包括基质附着区域（M/SARs）在内的DNA序列不会干扰核纤层蛋白Dm0尾部结构域与染色体的结合。综上所述，这些结果表明核纤层蛋白Dm0的尾部结构域与组蛋白H2A和H2B之间的相互作用可能在体内介导核纤层与染色体的附着。
