Question

What activities of a eukaryotic cell would be affected by dysfunctional histone proteins that can’t properly condense the DNA into nucleosomes?

How would these activities be affected?

Answer 1

If histones can't properly condense DNA into nucleosome then the first function that will be affected is improper chromatin condensation. As we know formation of nucleosome is the basis of chromosome organisation, thus, chromosome organisation will be affected. Most of the DNA will remain as double stranded helix. This may increase the probability of nuclease digestion.

Improper condensation of DNA will hamper the chromatin remodeling processes. Thus, the gene expression will no longer remains under the regulation of chromatin remodellers. Most of the gene will be expressed because RNA polymerase 2 will have much access to the DNA promoter sequences.

Histone tail post translational modifications like acetylation, methylation, sumoylation, ubiqutination will no longer have any regulation upon gene expression.

Heterochromatin formation will be hampered. There will be loss of heterochromatin formation at telomeres. Thus, exonuclease enzymes can start to degrade telomeric ends of DNA