Methylase
Encyclopedia
A methylase is an enzyme
that attaches a methyl group
to a molecule.
These are found in prokaryotes and eukaryotes. Bacteria use methylase to differentiate between foreign genetic material and their own, thus protecting their DNA from their own immune system. By placing a methyl group on a base of the recognition site of a restriction endonuclease, methylases prevent the enzyme
from cleaving the bacterial DNA.
There are methylases that can methylate DNA, RNA, proteins, or small molecules, for example, DNA methyltransferase
, which methylates cytosine residues
and adenine residues
in DNA
. A new relevant example is a methylase that alters the ribosomal RNA binding site of the antibiotic linezolid
and causes cross-resistance to other antibiotics which act on the ribosomal RNA. Plasmid
vectors capable of transmitting this gene are a cause of potentially dangerous cross resistance.
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
that attaches a methyl group
Methyl group
Methyl group is a functional group derived from methane, containing one carbon atom bonded to three hydrogen atoms —CH3. The group is often abbreviated Me. Such hydrocarbon groups occur in many organic compounds. The methyl group can be found in three forms: anion, cation and radical. The anion...
to a molecule.
These are found in prokaryotes and eukaryotes. Bacteria use methylase to differentiate between foreign genetic material and their own, thus protecting their DNA from their own immune system. By placing a methyl group on a base of the recognition site of a restriction endonuclease, methylases prevent the enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
from cleaving the bacterial DNA.
There are methylases that can methylate DNA, RNA, proteins, or small molecules, for example, DNA methyltransferase
DNA methyltransferase
In biochemistry, the DNA methyltransferase family of enzymescatalyze the transfer of a methyl group to DNA. DNA methylation serves a wide variety of biological functions...
, which methylates cytosine residues
Cytosine
Cytosine is one of the four main bases found in DNA and RNA, along with adenine, guanine, and thymine . It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached . The nucleoside of cytosine is cytidine...
and adenine residues
Adenine
Adenine is a nucleobase with a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate and the cofactors nicotinamide adenine dinucleotide and flavin adenine dinucleotide , and protein synthesis, as a chemical component of DNA...
in DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
. A new relevant example is a methylase that alters the ribosomal RNA binding site of the antibiotic linezolid
Linezolid
Linezolid is a synthetic antibiotic used for the treatment of serious infections caused by Gram-positive bacteria that are resistant to several other antibiotics...
and causes cross-resistance to other antibiotics which act on the ribosomal RNA. Plasmid
Plasmid
In microbiology and genetics, a plasmid is a DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA. They are double-stranded and, in many cases, circular...
vectors capable of transmitting this gene are a cause of potentially dangerous cross resistance.