Glutamate Racemase - Moonlighting Background

Moonlighting Background

Before the discovery of moonlighting proteins, it was generally believed by scientists that an enzyme only had one function which lead to the concept of "one gene, one enzyme". However, this concept no longer applies in science after the discovery that some proteins consist of both major and minor functions. This led to numerous studies attempting to relate the two functions to each other. The minor functions of these unique enzymes are called moonlighting functions, in which a protein can have a secondary functions not dependent upon the main function. These two functions of the moonlighting protein are found in a single polypeptide chain. Proteins that are multifunctional are not included due to gene fusion, families of homologous proteins, splice variants or promiscuous enzyme activities. The enzyme glutamate racemase (MurI) is an example of a moonlighting protein, functioning both in bacterial cell wall biosynthesis as well as in gyrase inhibition.