Transcription in bacteria

There are three primary domains of life, represented by the bacteria, archaea, and eukaryotes. Some of the clearest evidence for the independent evolution of these three groups of organisms is found in the transcriptional apparatus. While the basic chemistry is the same, the details of initiation and control of transcription in bacteria and in eukaryotes are very different.2643 The archaea share characteristics of both bacteria and eukaryotes. Archaeal RNA polymerases have a complexity similar to that of eukaryotes and also share a similar mechanism of initiation of transcription 265 266b... 

First we discuss the process of transcription in bacteria and then in eukaryotes. In both cases we consider the properties of the RNA polymerase(s) first. 

As with the establishment of the genetic code and information on the molecular mechanism of DNA replication (Chap. 16), the present detailed knowledge of the mechanism of DNA transcription to produce RNA rests largely upon studies with bacteria, particularly E. coli. It is convenient to treat transcription in bacteria first. 

Question Can a single RNA transcript in bacteria carry information from more than one gene ... 

Question Arc there inhibitors that discriminate between transcription in bacteria and eukaryotes ... 

Polycistronic mRNA, which forms as a primary transcript in bacteria, is a continuous length of RNA transcribed from a single promoter. It will therefore contain only one normal termination sequence (i.e.. ignoring a possible attenuator sequence before the first initiation codon). 

Mironov AS, Gusarov I, Raflkov R, Lopez LE, Shatalin K, Kreneva RA, Perumov DA, Nudler E. Sensing small molecules by nascent RNA a mechanism to control transcription in bacteria. Cell 2002 111 747-756. 

A novel mechanism for regulating transcription in bacteria was discovered by Charles Yanofsky and his colleagues as a result of their studies of the tryptophan operon. The 7-kb mRNA transcript from this operon encodes five enzymes that convert chorismate into tryptophan (Section 24.2.10). The mode of regulation of this operon is called attenuation, and it... 

Riboswitch-mediated gene regulation occurs after transcription initiation, as the regulatory element is part of the regulated transcript. In bacteria, preferred modes of regulation are at the levels of premature termination of transcription (referred to as transcriptional attenuation) and translation initiation. Rare examples identified so far in eukaryotic cells affect mRNA stability and splicing. 

Among the molecular mechanisms controlling the initiation of transcription in bacteria that might be considered specific mechanisms of control are those that involve a negative control element, or the repressor of the original model of Jacob and Monod (4A). 

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