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Bacterial transcription is the process in which messenger RNA transcripts of genetic material in bacteria are produced, to be translated for the production of proteins. Bacterial transcription occurs in the cytoplasm alongside translation. Unlike in eukaryotes, bacterial transcription and translation can occur simultaneously. This is impossible in eukaryotes, where transcription occurs in a membrane-bound nucleus while translation occurs outside the nucleus in the cytoplasm. In bacteria genetic material is not enclosed in a membrane-enclosed nucleus and has access to ribosomes in the cytoplasm. Transcription is known to be controlled by a variety of regulators in bacteria. Many of these transcription factors are homodimers containing helix-turn-helix DNA-binding motifs. ==Initiation== The following steps occur, in order, for transcription initiation: * RNA polymerase (RNAP) binds to one of several specificity factors, σ, to form a holoenzyme. In this form, it can recognize and bind to specific promoter regions in the DNA. The -35 region and the -10 ("Pribnow box") region comprise the core prokaryotic ''promoter'', and |T| stands for the ''terminator''. The DNA on the template strand between the +1 site and the terminator is transcribed into RNA, which is then translated into protein. At this stage, the DNA is double-stranded ("closed"). This holoenzyme/wound-DNA structure is referred to as the ''closed complex''. * The DNA is unwound and becomes single-stranded ("open") in the vicinity of the initiation site (defined as +1). This holoenzyme/unwound-DNA structure is called the ''open complex''. * The RNA polymerase transcribes the DNA (the beta subunit initiates the synthesis), but produces about 10 abortive (short, non-productive) transcripts which are unable to leave the RNA polymerase because the exit channel is blocked by the σ-factor. * The σ-factor eventually dissociates from the core enzyme, and elongation proceeds. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bacterial transcription」の詳細全文を読む スポンサード リンク
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