ABSTRACT

Nucleosomes ............................................................................ 123 10.3.3 Frequency of the Nucleosomes in Relation to Plasmid

Length ...................................................................................... 124 10.3.4 DNA Negative Supercoiling Affects Nucleosome

Formation ................................................................................. 126 10.3.5 Chromatin Salt-Dependent Conformational Changes ............. 127

10.4 Role of Linker Histone H1 in Nucleosome Compaction ....................... 128 10.4.1 Addition of Linker Histone H1 to Reconstituted 100-kb

Chromatin ................................................................................ 128 10.4.2 Dose-Dependency of Linker Histone H1 for Formation of

Thicker Fibers ................................................................................ 129 10.4.3 Physiological Ionic Strength Is Critical for the Formation of

30-nm Fibers ................................................................................... 129 10.5 Nonhistone Chromosome Proteins also Induced Chromatin

Compaction ............................................................................................ 130 10.5.1 Contribution of Matrix/Scaffold Proteins .................................131 10.5.2 Nonhistone Chromosomal Protein PC4 Induced

Chromatin Compaction by a Mechanism Different from the Histone H1-Induced Compaction ....................................... 133

10.6 Conclusion ............................................................................................. 133 Acknowledgment .............................................................................................. 133 References ......................................................................................................... 134

In eukaryotic cells, genomic DNA is packaged into the nucleus in a well-organized manner. The ultimate goal of chromosome researchers is to understand the molecular mechanisms underlying the process in which DNA is folded up and packed, together with a number of associated proteins, into the nucleus. For years, researchers have known that the chromosome is built up from DNA and protein, and also that the chromosome condenses to form an “X” shape in mitosis [1]. Although the precise number of steps is not known, it has generally been believed that there are at least several steps on the path from DNA to the chromosome [1,2].