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Methylation Zinc Finger

Methylation
In the chemical sciences, methylation denotes the addition of a methyl group to a substrate or the substitution of an atom or group by a methyl group. Methylation is a form of alkylation with, to be specific, a methyl group, rather than a larger carbon chain, replacing a hydrogen atom. These terms are commonly used in chemistry, biochemistry, soil science, and the biological sciences. In biological systems, methylation is catalyzed by enzymes; such methylation can be involved in modification of heavy metals, regulation of gene expression, regulation of protein function, and RNA metabolism. Methylation of heavy metals can also occur outside of biological systems. Chemical methylation of tissue samples is also one method for reducing certain histological staining artifacts.

Zinc Finger
A zinc finger is a small protein structural motif that is characterized by the coordination of one or more zinc ions in order to stabilize the fold. Unlike many other clearly defined supersecondary structures such as Greek keys or β hairpins, the secondary structures underlying the zinc finger are variable and differ from protein to protein. Proteins that contain zinc fingers (zinc finger proteins) can be classified into several different structural families depending on the ligands that coordinate the zinc ion. While such proteins exist in great variety, the vast majority typically function as interaction modules that bind DNA, RNA, proteins, or other small, useful molecules. The name "zinc finger" was originally coined to describe the finger-like appearance of a diagram showing the hypothesized structure of the repeated unit in Xenopus laevis transcription factor IIIA.[1]

E. Coli
Escherichia coli ( /ˌɛʃɨˈrɪkiə ˈkoʊlaɪ/;[1] commonly abbreviated E. coli) is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls due to food contamination.[2][3] The harmless strains are part of the normal flora of the gut, and can benefit their hosts by producing vitamin K2,[4] and by preventing the establishment of pathogenic bacteria within the intestine.[5][6] E. coli and related bacteria constitute about 0.1% of gut flora,[7] and fecal-oral transmission is the major route through which pathogenic strains of the bacterium cause disease. Cells are able to survive outside the body for a limited amount of time, which makes them ideal indicator organisms to test environmental samples for fecal contamination.[8][9] There is, however, a growing body of research that has examined environmentally persistent E. coli which can survive for extended periods of time outside of the host.[10] The bacterium can also be grown easily and inexpensively in a laboratory setting, and has been intensively investigated for over 60 years. E. coli is the most widely studied prokaryotic model organism,[citation needed] and an important species in the fields of biotechnology and microbiology, where it has served as the host organism for the majority of work with recombinant DNA.