The basis of chromatin fiber assembly within chromosomes studied by histone-DNA crosslinking followed by trypsin digestion
- 1 April 1980
- journal article
- research article
- Published by Springer Nature in Chromosoma
- Vol. 78 (1), 123-135
- https://doi.org/10.1007/bf00291911
Abstract
To determine the structural basis of chromatin assembly that leads to chromosome formation in mitosis, crosslinks were introduced by formaldehyde between contiguous components within chromosomes. Crosslinked stable products were then observed by electronmicroscopy after non-cross-linked portions were briefly digested by trypsin to unfold chromosomes. — When the DNA-histone crosslink was the primary product, trypsin readily unfolded the whole chromosome structure while preserving the 250 Å unit chromatin fiber intact; only a single unit fiber was tracked within the centromere region connecting the arms of each chromatid. When a histone polymer was formed by a prolonged formaldehyde crosslinking, trypsin digestion gave rise to chromatin fibers interacting with others at certain distances, and the typical chromosome structure remained unchanged. Regardless of the degree of crosslinking, there were neither thick supercoiled unit fibers nor proteinaceous cores. — These results suggest that the fiber connection may represent, to some extent, the interacting sites of folded chromatin fibers in situ within chromosomes, and also that the 250 Å unit fibers are the sole, highest structural basis in chromosomes. Since virtually no appreciable histone digestion took place in the crosslinked chromosomes, the observation that even after DNA-histone crosslinking the fiber interacting sites were accessible to trypsin preferentially over other portions, may be consistent with our recent results that the exposed, lysine-rich tails of histones represent such interacting sites.Keywords
This publication has 41 references indexed in Scilit:
- Fidelity of ribosomal ribonucleic acid synthesis by nucleoli and nucleolar chromatinBiochemistry, 1977
- Biochemical and Electron‐Microscopic Evidence that the Subunit Structure of Chinese‐Hamster‐Ovary Interphase Chromatin Is Conserved in Mitotic ChromosomesEuropean Journal of Biochemistry, 1976
- The presence of F3-F2a1 dimers and F1 oligomers in chromatinBiochemical and Biophysical Research Communications, 1975
- GLUTARALDEHYDE FIXATION OF ISOLATED EUCARYOTIC NUCLEIThe Journal of cell biology, 1973
- The structure of chromatid ends and of the ends of experimentally procuced chromatid fragments as revealed by trypsin treatment of Vicia faba chromosomesMutation Research, 1973
- INDUCTION OF PROPHASE IN INTERPHASE NUCLEI BY FUSION WITH METAPHASE CELLSThe Journal of cell biology, 1972
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970
- The ultrastructure and strandedness of chromosomes from two species of ViciaExperimental Cell Research, 1968
- STRANDEDNESS OF VICIA FABA CHROMOSOMES AS REVEALED BY ENZYME DIGESTION STUDIESThe Journal of cell biology, 1965
- Chromosome Fibers from an Interphase NucleusScience, 1963