Nocturnin is a human hydrolase enzyme that is involved in metabolism and its expression is controlled by the rhythmic circadian clock. It is encoded by the NOCT gene located on chromosome 4. Nocturnin contains a c-terminal structural domain of the Endonuclease/Exonuclease/phosphatase family.
The Drosophila melanogasterortholog of Nocturnin is Curled. Knockouts of Curled lead to the curled wing phenotype in fruit flies. The curled wing phenotype was first discovered by Thomas Hunt Morgan in 1915.[1] In mice the Nocturnin ortholog is responsible for controlling diet and weight-gain, knockout mice do not gain weight when placed on a high-fat diet, when compared to normal mice containing Nocturnin.[2] In mice it has also been shown that Nocturnin is rhythmically expressed even when mice are placed in complete darkness, demonstrating that Nocturnin expression is driven by our body's internal clock.[3]
Enzymatic activity
Nocturnin was previously thought to deadenylatemRNAs of metabolic genes,[4] but two studies in 2018 demonstrated that Nocturnin does not directly posses ribonuclease activity.[5][6]
↑Abshire ET, Chasseur J, Bohn JA, Del Rizzo PA, Freddolino PL, Goldstrohm AC, Trievel RC (2018). "The structure of human Nocturnin reveals a conserved ribonuclease domain that represses target transcript translation and abundance in cells". Nucleic Acids Research. 46 (12). doi:10.1093/nar/gky412.