| Popis: |
Transcription, the synthesis of RNA from DNA, is the first step in gene expression. It is a multistep biochemical process. RNA polymerase, the enzyme that catalyzes transcription, locates and binds a specific promoter sequence on the template DNA, unwinds a small region surrounding a specific start site, initiates the synthesis of an RNA chain, elongates the chain to a definite stop site, and finally releases the completed transcript and dissociates itself from the template DNA. RNA polymerase is composed of a battery of distinct polypeptide subunits whose function requires accurate interaction not only with each other but also with the template DNA, four ribonucleotide precursor molecules, the emerging RNA chain, and numerous other ancillary subunits that influence one or more individual steps of transcription. The overall chemical mechanism of the basic transcription process is identical in procaryotic and eucaryotic organisms, with certain features of the individual components of the transcription apparatus conserved from bacteria to man. However, the two types of organisms differ more in the individual protein components and the ancillary proteins than they show identity. This diversity makes the transcription apparatus of pathogenic bacteria an ideal target for developing novel antibacterial drugs. |
