Involvement of H1 and other chromatin proteins in the formation of DNA-protein cross-links induced by visible light in the presence of methylene blue
✍ Scribed by Ratna Lalwani; Subhankar Maiti; Sheela Mukherji
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 779 KB
- Volume
- 27
- Category
- Article
- ISSN
- 1011-1344
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✦ Synopsis
The formation of DNA-protein cross-links (DPCs), induced by irradiation with visible light, was studied in methylene bluetreated (MB-treated) chromatin and HI-depleted chromatin. The effects of the MB concentration and radiation dose were studied using sodium dodecylsulphate-chloroform-isoamyl alcohol assay and sodium dodecylsulphate-polyacrylamide gel electrophoresis. Under identical experimental conditions, DPC formation was less in HI-depleted chromatin (70%) than in chromatin (92%). The non-histone proteins and core proteins of chromatin contributed towards DPC formation. Of the core proteins, H2A was more cross-linked than H4, whereas the bands for H2B and H3 melted into one in chromatin and HIdepleted chromatin. In both cases, the gel pattern showed the appearance of two new protein bands with approximate molecular weights of 27 kDa and 29 kDa as a result of histone-histone cross-linking. Viscometric studies showed that the dissociation of the compact structure of chromatin in 2 M NaCI was more extensive in irradiated, MB-treated, HI-depleted chromatin than in irradiated, MB-treated chromatin, indicating a reduction in the amount of DPC formation in HI-depleted chromatin.