Methyltransferases are a large group of enzymes that all methylate their substrates but can be split into several subclasses based on their structural features. The most common class of methyltransferases is class I, all of which contain a Rossmann fold for binding S-Adenosyl methionine (SAM). Class II methyltransferases contain a SET domain, which are exemplified by SET domain histone methyltransferases, and class III methyltransferases, which are membrane associated. Methyltransferases can also be grouped as different types utilizing different substrates in methyl transfer reactions. These types include protein methyltransferases, DNA/RNA methyltransferases, natural product methyltransferases, and non-SAM dependent methyltransferases. SAM is the classical methyl donor for methyltransferases, however, examples of other methyl donors are seen in nature. The general mechanism for methyl transfer is a SN2-like nucleophilic attack where the methionine sulfur serves as the leaving group and the methyl group attached to it acts as the electrophile that transfers the methyl group to the enzyme substrate. SAM is converted to S-Adenosyl homocysteine (SAH) during this process. The breaking of the SAM-methyl bond and the formation of the substrate-methyl bond happen nearly simultaneously. These enzymatic reactions are found in many pathways and are implicated in genetic diseases, cancer, and metabolic diseases. Another type of methyl transfer is the radical S-Adenosyl methionine (SAM) which is the methylation of unactivated carbon atoms in primary metabolites, proteins, lipids, and RNA.
The exosome complex is a multi-protein intracellular complex capable of degrading various types of RNA molecules. Exosome complexes are found in both eukaryotic cells and archaea, while in bacteria a simpler complex called the degradosome carries out similar functions.
In molecular biology, the 5.8S ribosomal RNA is a non-coding RNA component of the large subunit of the eukaryotic ribosome and so plays an important role in protein translation. It is transcribed by RNA polymerase I as part of the 45S precursor that also contains 18S and 28S rRNA. Its function is thought to be in ribosome translocation. It is also known to form covalent linkage to the p53 tumour suppressor protein. 5.8S rRNA can be used as a reference gene for miRNA detection. The 5.8S ribosomal RNA is used to better understand other rRNA processes and pathways in the cell.
In enzymology, a rRNA (adenine-N6-)-methyltransferase (EC 2.1.1.48) is an enzyme that catalyzes the chemical reaction
Lipoyl synthase is an enzyme that belongs to the radical SAM (S-adenosyl methionine) family. Within the radical SAM superfamily, lipoyl synthase is in a sub-family of enzymes that catalyze sulfur insertion reactions. The enzymes in this subfamily differ from general radical SAM enzymes, as they contain two 4Fe-4S clusters. From these clusters, the enzymes obtain the sulfur groups that will be transferred onto the corresponding substrates. This particular enzyme participates in the final step of lipoic acid metabolism, transferring two sulfur atoms from its 4Fe-4S cluster onto the protein N6-(octanoyl)lysine through radical generation. This enzyme is usually localized to the mitochondria. Two organisms that have been extensively studied with regards to this enzyme are Escherichia coli and Mycobacterium tuberculosis. It is currently being studied in other organisms including yeast, plants, and humans.
S-Adenosylmethionine synthetase, also known as methionine adenosyltransferase (MAT), is an enzyme that creates S-adenosylmethionine by reacting methionine and ATP.
23S rRNA (uridine2552-2'-O)-methyltransferase is an enzyme with systematic name S-adenosyl-L-methionine:23S rRNA (uridine2552-2'-O-)-methyltransferase. This enzyme catalyses the following chemical reaction
27S pre-rRNA (guanosine2922-2'-O)-methyltransferase is an enzyme with systematic name S-adenosyl-L-methionine:27S pre-rRNA (guanosine2922-2'-O-)-methyltransferase. This enzyme catalyses the following chemical reaction
16S rRNA (guanine1405-N7)-methyltransferase (EC 2.1.1.179, methyltransferase Sgm, m7G1405 Mtase, Sgm Mtase, Sgm, sisomicin-gentamicin methyltransferase, sisomicin-gentamicin methylase, GrmA, RmtB, RmtC, ArmA) is an enzyme with systematic name S-adenosyl-L-methionine:16S rRNA (guanine1405-N7)-methyltransferase. This enzyme catalyses the following chemical reaction
23S rRNA (adenine1618-N6)-methyltransferase (EC 2.1.1.181, rRNA large subunit methyltransferase F, YbiN protein, rlmF (gene), m6A1618 methyltransferase) is an enzyme with systematic name S-adenosyl-L-methionine:23S rRNA (adenine1618-N6)-methyltransferase. This enzyme catalyses the following chemical reaction
16S rRNA (adenine1518-N6/adenine1519-N6)-dimethyltransferase (EC 2.1.1.182, S-adenosylmethionine-6-N',N'-adenosyl (rRNA) dimethyltransferase, KsgA, ksgA methyltransferase) is an enzyme with systematic name S-adenosyl-L-methionine:16S rRNA (adenine1518-N6/adenine1519-N6)-dimethyltransferase. This enzyme catalyses the following chemical reaction
23S rRNA (adenine2085-N6)-dimethyltransferase (EC 2.1.1.184, ErmC' methyltransferase, ermC methylase, ermC 23S rRNA methyltransferase, rRNA:m6A methyltransferase ErmC', ErmC', rRNA methyltransferase ErmC' ) is an enzyme with systematic name S-adenosyl-L-methionine:23S rRNA (adenine2085-N6)-dimethyltransferase. This enzyme catalyses the following chemical reaction
23S rRNA (adenine2503-C2,C8)-dimethyltransferase (EC 2.1.1.194, Cfr, Cfr methyltransferase, Cfr rRNA methyltransferase) is an enzyme with systematic name S-adenosyl-L-methionine:23S rRNA (adenine2503-C2,C8)-dimethyltransferase. This enzyme catalyses the following chemical reaction
Multisite-specific tRNA:(cytosine-C5)-methyltransferase is an enzyme with systematic name S-adenosyl-L-methionine:tRNA (cytosine-C5)-methyltransferase. This enzyme catalyses the following chemical reaction
TRNA (guanine10-N2)-dimethyltransferase (EC 2.1.1.213, PAB1283, N(2),N(2)-dimethylguanosine tRNA methyltransferase, Trm-G10, PabTrm-G10, PabTrm-m2 2G10 enzyme) is an enzyme with systematic name S-adenosyl-L-methionine:tRNA (guanine10-N2)-dimethyltransferase. This enzyme catalyses the following chemical reaction
TRNA (guanine26-N2/guanine27-N2)-dimethyltransferase (EC 2.1.1.215, Trm1, tRNA (N2,N2-guanine)-dimethyltransferase, tRNA (m2(2G26) methyltransferase, Trm1[tRNA (m2(2)G26) methyltransferase]) is an enzyme with systematic name S-adenosyl-L-methionine:tRNA (guanine26-N2/guanine27-N2)-dimethyltransferase. This enzyme catalyses the following chemical reaction
TRNA (guanine26-N2)-dimethyltransferase (EC 2.1.1.216, Trm1p, TRM1, tRNA (m22G26)dimethyltransferase) is an enzyme with systematic name S-adenosyl-L-methionine:tRNA (guanine26-N2)-dimethyltransferase. This enzyme catalyses the following chemical reaction
tRNA (guanine37-N1)-methyltransferase (EC 2.1.1.228, TrmD, tRNA (m1G37) methyltransferase, transfer RNA (m1G37) methyltransferase, Trm5p, TRMT5, tRNA-(N1G37) methyltransferase, MJ0883 (gene)) is an enzyme with systematic name S-adenosyl-L-methionine:tRNA (guanine37-N1)-methyltransferase. This enzyme catalyses the following chemical reaction
DTDP-3-amino-3,6-dideoxy-alpha-D-glucopyranose N,N-dimethyltransferase is an enzyme with systematic name S-adenosyl-L-methionine:dTDP-3-amino-3,6-dideoxy-alpha-D-glucopyranose 3-N,N-dimethyltransferase. This enzyme catalyses the following chemical reaction
RRNA small subunit pseudouridine methyltransferase Nep1 (EC 2.1.1.260, Nep1, nucleolar essential protein 1) is an enzyme with systematic name S-adenosyl-L-methionine:18S rRNA (pseudouridine1191-N1)-methyltransferase. This enzyme catalyses the following chemical reaction
