Modulation of higher-order structure of F-factor DNA- protein complex and its partition function

I. F-因子DNA和sop基因产物之间的相互作用. SopA和DNA之间的相互作用：发现Sop操纵子-启动子区域中的四个SopA结合位点在抑制方面几乎相等。获得了SopA蛋白晶体. SopB和DNA之间的相互作用：研究表明，SopB引起的基因沉默是由于局部高浓度的蛋白质引起的非特异性DNA结合。寻找寄主因子互作sop基因产物. SopA相互作用蛋白质：远蛋白质分析显示四种蛋白质与SopA相互作用。经鉴定均为核糖体蛋白. SopB相互作用蛋白质：可逆交联揭示了一个约。70 KDa蛋白与SopB相互作用。发现了一种具有不寻常pI的SopB小种。BrCN降解产物的MS分析表明，未知的修饰发生在蛋白质的两端附近。染色体分离和DNA-蛋白质相互作用.染色体分离相关蛋白的细胞内定位：发现人DNA拓扑异构酶IIIβ与M期染色体相关。与参与染色体分离的蛋白质相互作用的蛋白质的表征：检测人DnaH同源物HSJ 2的两种同种型的细胞内分布，HSJ 2已通过双杂交筛选作为人拓扑异构酶IIIa作为诱饵分离。较长的基因产物定位于细胞核，而较短的基因产物在整个细胞中均匀分布。

I. Interaction between F-factor DNA and sop gene products.1. Interaction between SopA and DNA : Four SopA-binding sites in the sop operator-promoter region were found to be nearly equivalent in repression. Crystals of SopA protein were obtained.2. Interaction between SopB and DNA : It was indicated that gene silencing effected by SopB results from a high local concentration of the protein causing non-specific DNA binding.II. Search for host factors interaction sop gene products.1. SopA-interacting proteins : Far-Western analysis revealed four proteins interacting with SopA. All of them were identified as ribosomal proteins.2. SopB-interacting proteins : Reversible cross-linking revealed a ca. 70 KDa protein interacting with SopB. A minor species of SopB with an unusual pI was discovered. MS analysis of BrCN degradation products showed that unknown modifications occurred close to both ends of the protein.III. Chromosome segregation and DNA-protein interaction.1. Intracellular localization of a protein involved in chromosome segregation : Human DNA topoisoemrase IIIβ was found to be associated with chromosomes in the M-phase.2. Characterization of a protein interacting with a protein involved in chromosome segregation : The intracellular distribution was examined for the two isoforms of a human DnaH homologue, HSJ2, which had been isolated by two-hybrid screening as human topoisomerase IIIa as bait. The longer gene product was localized to the nucleus, whereas the shorter one was observed uniformly throughout the cell.