Macro | |||||||||
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![]() Crystal structure of the macro-domain of human core histone variant macroh2a1.1 | |||||||||
Identifiers | |||||||||
Symbol | Macro | ||||||||
Pfam | PF01661 | ||||||||
Pfam clan | CL0223 | ||||||||
InterPro | IPR002589 | ||||||||
SCOP2 | 1vhu / SCOPe / SUPFAM | ||||||||
CDD | cd02749 | ||||||||
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In molecular biology, the Macro domain (often also written macrodomain) or A1pp domain is an ancient, evolutionary conserved structural module found in all kingdoms of life as well as some viruses. [1] Macro domains are modules of about 180 amino acids that can bind ADP-ribose, an NAD metabolite, or related ligands. Binding to ADP-ribose can be either covalent or non-covalent: [2] in certain cases it is believed to bind non-covalently, [3] while in other cases (such as Aprataxin) it appears to bind both non-covalently through a zinc finger motif, and covalently through a separate region of the protein. [4]
The domain was described originally in association with the ADP-ribose 1-phosphate (Appr-1-P)-processing activity (A1pp) of the yeast YBR022W protein and called A1pp. [5] However, the domain has been renamed Macro as it is the C-terminal domain of mammalian core histone macro-H2A. [6] [7] Macro domain proteins can be found in eukaryotes, in (mostly pathogenic) bacteria, in archaea and in ssRNA viruses, such as coronaviruses, Rubella and Hepatitis E viruses. In vertebrates the domain occurs in e.g. histone macroH2A, predicted poly-ADP-ribose polymerases (PARPs) and B aggressive lymphoma (BAL) protein. Zinc-containing macro domains (Zn-Macros) are primarily encountered in pathogenic microorganisms and have structurally distinct features from other macro domains, which include their function being strictly dependent on a catalytic zinc within the active site. [8] [9]
ADP-ribosylation of proteins is an important post-translational modification that occurs in a variety of biological processes, including DNA repair, regulation of transcription, chromatin biology, maintenance of genomic stability, telomere dynamics, [10] cell differentiation and proliferation, [11] necrosis and apoptosis, [12] and long-term memory formation. [13] The Macro domain recognises the ADP-ribose nucleotide and in some cases poly-ADP-ribose, and is thus a high-affinity ADP-ribose-binding module found in a number of otherwise unrelated proteins. [14]
ADP-ribosylation of DNA is relatively uncommon and has only been described for a small number of toxins that include pierisin, [15] scabin [16] and DarT. [17] [18] The Macro domain from the antitoxin DarG of the toxin-antitoxin system DarTG, both binds and removes the ADP-ribose modification added to DNA by the toxin DarT. [17] [18] The Macro domain from human, macroH2A1.1, binds an NAD metabolite O-acetyl-ADP-ribose. [19]
Class | Subclass | Species | Activity |
---|---|---|---|
MacroH2A-like | e | ADP-ribose binding | |
MacroD-type | ‘classic’ | a, b, e, v | ADP-ribosyl bond hydrolysis |
Zn-dependent | b, e | ADP-ribosyl bond hydrolysis | |
GDAP2-like | e | ADP-ribose binding | |
ALC1-like | b, e | ADP-ribose binding or ADP-ribosyl bond hydrolysis | |
PARG-like | PARG_cat | e | ADP-ribosyl bond hydrolysis |
mPARG (DUF2263) | b, e, v | ADP-ribosyl bond hydrolysis | |
Macro2-type | e, v | ADP-ribosyl bond hydrolysis | |
SUD-M-like | v | RNA binding | |
DUF2362 | e | unknown | |
a, Archaea; b, Bacteria; e, Eukarya; v, Virus |
The 3D structure of the Macro domain describes a mixed alpha/beta fold of a mixed beta sheet sandwiched between four helices with the ligand-binding pocket lies within the fold. [14] Several Macro domain-only domains are shorter than the structure of AF1521 and lack either the first strand or the C-terminal helix 5. Well conserved residues form a hydrophobic cleft and cluster around the AF1521-ADP-ribose binding site. [7] [14] [19] [20]
In biology, histones are highly basic proteins abundant in lysine and arginine residues that are found in eukaryotic cell nuclei and in most Archaeal phyla. They act as spools around which DNA winds to create structural units called nucleosomes. Nucleosomes in turn are wrapped into 30-nanometer fibers that form tightly packed chromatin. Histones prevent DNA from becoming tangled and protect it from DNA damage. In addition, histones play important roles in gene regulation and DNA replication. Without histones, unwound DNA in chromosomes would be very long. For example, each human cell has about 1.8 meters of DNA if completely stretched out; however, when wound about histones, this length is reduced to about 90 micrometers (0.09 mm) of 30 nm diameter chromatin fibers.
A nucleosome is the basic structural unit of DNA packaging in eukaryotes. The structure of a nucleosome consists of a segment of DNA wound around eight histone proteins and resembles thread wrapped around a spool. The nucleosome is the fundamental subunit of chromatin. Each nucleosome is composed of a little less than two turns of DNA wrapped around a set of eight proteins called histones, which are known as a histone octamer. Each histone octamer is composed of two copies each of the histone proteins H2A, H2B, H3, and H4.
Histone acetyltransferases (HATs) are enzymes that acetylate conserved lysine amino acids on histone proteins by transferring an acetyl group from acetyl-CoA to form ε-N-acetyllysine. DNA is wrapped around histones, and, by transferring an acetyl group to the histones, genes can be turned on and off. In general, histone acetylation increases gene expression.
Poly (ADP-ribose) polymerase (PARP) is a family of proteins involved in a number of cellular processes such as DNA repair, genomic stability, and programmed cell death.
Histone H2A is one of the five main histone proteins involved in the structure of chromatin in eukaryotic cells.
Histone-modifying enzymes are enzymes involved in the modification of histone substrates after protein translation and affect cellular processes including gene expression. To safely store the eukaryotic genome, DNA is wrapped around four core histone proteins, which then join to form nucleosomes. These nucleosomes further fold together into highly condensed chromatin, which renders the organism's genetic material far less accessible to the factors required for gene transcription, DNA replication, recombination and repair. Subsequently, eukaryotic organisms have developed intricate mechanisms to overcome this repressive barrier imposed by the chromatin through histone modification, a type of post-translational modification which typically involves covalently attaching certain groups to histone residues. Once added to the histone, these groups elicit either a loose and open histone conformation, euchromatin, or a tight and closed histone conformation, heterochromatin. Euchromatin marks active transcription and gene expression, as the light packing of histones in this way allows entry for proteins involved in the transcription process. As such, the tightly packed heterochromatin marks the absence of current gene expression.
ADP-ribosylation is the addition of one or more ADP-ribose moieties to a protein. It is a reversible post-translational modification that is involved in many cellular processes, including cell signaling, DNA repair, gene regulation and apoptosis. Improper ADP-ribosylation has been implicated in some forms of cancer. It is also the basis for the toxicity of bacterial compounds such as cholera toxin, diphtheria toxin, and others.
Poly [ADP-ribose] polymerase 1 (PARP-1) also known as NAD+ ADP-ribosyltransferase 1 or poly[ADP-ribose] synthase 1 is an enzyme that in humans is encoded by the PARP1 gene. It is the most abundant of the PARP family of enzymes, accounting for 90% of the NAD+ used by the family. PARP1 is mostly present in cell nucleus, but cytosolic fraction of this protein was also reported.
Core histone macro-H2A.1 is a protein that in humans is encoded by the H2AFY gene.
Tankyrase, also known as tankyrase 1, is an enzyme that in humans is encoded by the TNKS gene. It inhibits the binding of TERF1 to telomeric DNA. Tankyrase attracts substantial interest in cancer research through its interaction with AXIN1 and AXIN2, which are negative regulators of pro-oncogenic β-catenin signaling. Importantly, activity in the β-catenin destruction complex can be increased by tankyrase inhibitors and thus such inhibitors are a potential therapeutic option to reduce the growth of β-catenin-dependent cancers.
Histone H1.1 is a protein that in humans is encoded by the HIST1H1A gene.
Poly [ADP-ribose] polymerase 2 is an enzyme that in humans is encoded by the PARP2 gene. It is one of the PARP family of enzymes.
(ADP-ribosyl)hydrolase 3 (ARH3) is an enzyme that in humans is encoded by the ADPRHL2 gene (also called ADPRS). This enzyme reverses the proteins’ post-translational addition of ADP-ribose to serine residues as part of the DNA damage response The enzyme is also known to cleave poly(ADP-ribose) polymers, 1''-O-acetyl-ADP-ribose and alpha-NAD+
In molecular biology, the (ADP-ribosyl)hydrolase (ARH) family contains enzymes which catalyses the hydrolysis of ADP-ribosyl modifications from proteins, nucleic acids and small molecules.
Poly (ADP-ribose) glycohydrolase is an enzyme that in humans is encoded by the PARG gene.
(ADP-ribosyl)hydrolase 1, also termed [Protein ADP-ribosylarginine] hydrolase and protein-Nω-(ADP-D-ribosyl)-L-arginine ADP-ribosylhydrolase (EC 3.2.2.19), is an enzyme that in humans is encoded by the ADPRH gene. This enzyme is a specific mono(ADP-ribosyl)hydrolase that catalyses the removal of an ADP-ribosyl modification from target arginine residues of protein substrates. The chemical reactions can formally be described as follows:
Parthanatos is a form of programmed cell death that is distinct from other cell death processes such as necrosis and apoptosis. While necrosis is caused by acute cell injury resulting in traumatic cell death and apoptosis is a highly controlled process signalled by apoptotic intracellular signals, parthanatos is caused by the accumulation of Poly(ADP ribose) (PAR) and the nuclear translocation of apoptosis-inducing factor (AIF) from mitochondria. Parthanatos is also known as PARP-1 dependent cell death. PARP-1 mediates parthanatos when it is over-activated in response to extreme genomic stress and synthesizes PAR which causes nuclear translocation of AIF. Parthanatos is involved in diseases that afflict hundreds of millions of people worldwide. Well known diseases involving parthanatos include Parkinson's disease, stroke, heart attack, and diabetes. It also has potential use as a treatment for ameliorating disease and various medical conditions such as diabetes and obesity.
Histone variants are proteins that substitute for the core canonical histones in nucleosomes in eukaryotes and often confer specific structural and functional features. The term might also include a set of linker histone (H1) variants, which lack a distinct canonical isoform. The differences between the core canonical histones and their variants can be summarized as follows: (1) canonical histones are replication-dependent and are expressed during the S-phase of cell cycle whereas histone variants are replication-independent and are expressed during the whole cell cycle; (2) in animals, the genes encoding canonical histones are typically clustered along the chromosome, are present in multiple copies and are among the most conserved proteins known, whereas histone variants are often single-copy genes and show high degree of variation among species; (3) canonical histone genes lack introns and use a stem loop structure at the 3’ end of their mRNA, whereas histone variant genes may have introns and their mRNA tail is usually polyadenylated. Complex multicellular organisms typically have a large number of histone variants providing a variety of different functions. Recent data are accumulating about the roles of diverse histone variants highlighting the functional links between variants and the delicate regulation of organism development.
Deltex E3 ubiquitin ligase 3L is a protein that in humans is encoded by the DTX3L gene. It functions as an ubiquitin ligase (E3), and is over-expressed in chemotherapy-resistant lymphomas. It is a member of the DTX family of proteins. Among other roles it has a function in DNA damage repair.