Final answer:
Nucleosomes are dynamically structured and subject to changes catalyzed by enzymes like HATs, de-acetylases, methyl transferases, and kinases. These modifications alter chromatin structure, thereby regulating gene expression. Mutations in chromatin remodeling proteins can be associated with diseases, including cancer.
Step-by-step explanation:
The dynamic structure of nucleosomes is frequently subjected to changes catalyzed by various enzymes that remodel chromatin. These enzymes include histone acetyltransferases (HAT enzymes), de-acetylases, methyl transferases, and kinases. These enzymes carry out histone modification, such as acetylation, de-acetylation, methylation, and phosphorylation, which affect nucleosome mobility and positioning. Particularly, acetylation of histones tends to unwind nucleosomes, making the underlying DNA more accessible for transcription. Conversely, de-acetylation promotes chromatin condensation, reducing accessibility. Methylation can also impact gene expression by altering chromatin structure, where certain patterns of methylation are associated with gene suppression or activation.
The flexibility of this system is crucial for regulating gene transcription, which can alter the expression of genes to meet the cellular needs. Moreover, such epigenetic changes can be linked to diseases; for example, mutations in proteins involved in chromatin remodeling have been associated with various cancers. DNA accessible regions allow gene activation, while methylation and chemical modifications that alter nucleosome spacing can change gene expression patterns significantly.