Are histone mRNAs polyadenylated?

The metazoan replication-dependent histone mRNAs are not polyadenylated but end instead in a conserved stem-loop, while in plants, and most single-cell eukaryotes, the replication-dependent histone mRNAs are polyadenylated [1].

Why are histone mRNAs not polyadenylated?

In metazoans, histone mRNAs are not polyadenylated but end in a conserved stem-loop. Stem-loop binding protein (SLBP) binds to the stem-loop and is required for all steps in histone mRNA metabolism. The genes for the five histone proteins are linked. A histone locus body (HLB) forms at each histone gene locus.

How are histone mRNAs degraded?

Histone mRNAs end in a conserved stem–loop rather than a poly(A) tail. Degradation of histone mRNAs requires the stem–loop sequence, which binds the stem–loop-binding protein (SLBP), active translation of the histone mRNA, and the location of the stem–loop close to the termination codon.

Where does translation of histone mRNA occur?

SLBP remains bound to the histone mRNA as it goes to the cytoplasm, where histone mRNA is circularized through a complex of proteins including at least SLBP, SLBP-interacting protein 1 (SLIP1) and eukaryotic translation initiation factor 4-γ (EIF4G) mediating translation of histone mRNA.

What DNA is transcriptionally inactive?

Transcriptionally inactive heterochromatin plays a vital role in sustaining stable structure of specialized chromosomal regions with repetitive DNA, such as centromeres and telomeres. Loss of integrity in these chromosomal areas can lead to detrimental effects and drive cancer development.

How are histones translated?

SLBP is required for histone mRNA processing, as well as translation. We show here, using histone mRNAs whose translation can be regulated by the iron response element, that histone mRNAs need to be actively translated for their rapid degradation following the inhibition of DNA synthesis.

Do histones have poly A tails?

The metazoan replication-dependent histone mRNAs are unusual as they are the only eukaryotic mRNAs that lack poly(A) tails. These RNAs are produced mainly in the S-phase of somatic cells and produce histones to package newly replicated DNA into chromatin.

What is the process called that changes DNA to mRNA?

Transcription is the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA).

What is the meaning of transcriptionally?

: the process of constructing a messenger RNA molecule using a DNA molecule as a template with resulting transfer of genetic information to the messenger RNA — compare reverse transcription, translation. Other Words from transcription. transcriptional \ -​shnəl, -​shən-​ᵊl \ adjective. transcriptionally \ -​ē \ adverb.

What does transcriptionally active mean?

Transcriptionally active or potentially active genes can be distinguished by several criteria from inactive sequences. Active genes show both an increased general sensitivity to endonucleases like DNase I or micrococcal nuclease and the presence of nuclease hypersensitive sites.

What is a modification to histone proteins?

A modification is a covalent post-translational modification (PTM) to histone proteins which includes , , , ubiquitylation, and sumoylation. The PTMs made to can impact by altering chromatin structure or recruiting histone modifiers. Histone proteins act to package DNA, which wraps around the eight histones, into chromosomes.

What are histone H3 modifications?

Histone modifications act in diverse biological processes such as transcriptional activation/inactivation, chromosome packaging, and DNA damage/repair. In most species, histone H3 is primarily acetylated at lysines 9, 14, 18, 23, and 56, methylated at arginine 2 and lysines 4, 9, 27, 36, and 79, and phosphorylated at ser10, ser28, Thr3, and Thr11.

Are histone modifications epigenetic markings?

Various histone modifications are also linked to DNA methylation and cell identity determination; hence they are now considered epigenetic markings. Distinct epigenetic changes, including changes in certain histone modifications, have been observed in various aged cells and tissues.

What is a histone tail modification?

N-terminal histone tails (blue) are shown protruding from H3 and H4. A modification is a covalent post-translational modification (PTM) to histone proteins which includes , , , ubiquitylation, and sumoylation.