Question

2. Compare the mechanisms by which acetylation and methylation of histone lysines affect transcription. Be sure to discuss how these modifications impact the charge of the lysine and the association of other proteins.

Answer 1

Modification K-ac. Histone target (s) of various modifications and their associated functions. Function Target Residus * Methylation (me) Repave, K-med, K-me 2, K-me3. transcription Transcription R-mes, R-me 2a, R-me as * Acetylation (ac) Condensation, Repaire, transcription, owocciolin veplication or geblice Hovi a - asąmmetric, S = symmetric, k-lysine, R-oeginine. DNA methylation is commonly associated with gene silencing, and a hink between histone deacetylation and DNA methylation has been established. The impact of DNA methylation on transcription is greater when it is in the transcription whit, and it is primarily a local effect DNA methylation represses Eukaryotic transcription is highly transcription, loss of methylation regulated ted where acetylation is is associated with gene activation. now known to play a major role DNA methylation can directly inter in this regulation. Acetyltransferase - fere with transcription factor binding. enzymes that at on particular Methyl-CpG binding proteins can lysine side chains of histones and mediate histone deacetylases to other profeins are intimately methylated DNA. With fungi, methy-involved in transcriptional -lation impacts transcriptional activation. HAT (Histone acetyl initiation. transferase) ensaymatically transfers Methylation adjacent to promoter inhibit transcription. oder acetyl CoA to the e-amino may group of certain lysine side charice with histone's basic N-terminal tail. elongation more than Si

Histone depending Proteiris associated with lation ston juborib co Acetylated deacetylation Lysine acetylation, which repress gene expression neutralization of a tail region's Unline acetylation, methyla positive charge, is postulated tion of different parts of the to weaken histone-DNA or nucleo- N-terminal tails of H3 and 44 -some- nucleosome interactions histones is associated with both and/or & signal a conformational repressed and active chromatin, change destabilizing nucleosome on amino acid that structure on arrangement and is modified in the histone tail. giving other nuclear factors H3K9 - gene silencing/condensa- such as the transcription complex, Hak37 tion (lysine at gtposition more access to a genetic locus. H3, K39transcription activation profecius associated we tú H4 K8 Clysine at 4th position of H3) position Bron omo domani Enzyme - methyl transferans. MAWILI HAKS, H2A KY, H28K5, HAB KI2 make up the nucleosone in methylated histones - Clocomo cone contenin flexible amino and terminus 11-37 residues extending from the fixed structure of the nucleosomes. CH₃ Totovit CH2 berita.bob. monitorid CH₂ domain Acetyl COA COASH NH3 dd at - Lysine // lysine NH CH2 THDACI, I, O CH2 de CH₂ Acetate H₂O Corrosta (M2 C CH2 leogan moitola CH2 hoitoon TA! .n HDACT (Sirtwins) Huic no con NADT lanN- и O-Acety! ADP ribose Nicotinamide HN ОР

CH3 CH3 CH₂ Lysine Monomethyl Dimethyl lyone lycine CH₃ CHA Trimethyl lysine. сня NH₂ NHg NH+ KMT KMT KMT R Protein Protein Protein . Protein KDM KOM KDM KMT - Kmethyl transferase KDM-k deneytiglase.