TTGACA

TTGACA is a hexamer DNA sequence that serves as the -35 promoter element in many bacterial promoters. It is typically located about 35 nucleotides upstream of the transcription start site. Together with the adjacent -10 element, commonly TATAAT, TTGACA forms the promoter core recognized by the RNA polymerase holoenzyme containing sigma factor, most notably sigma70 in many bacteria. The -35 and -10 elements are usually separated by about 16 to 18 base pairs, though spacing can vary among promoters.

Promoter strength often correlates with similarity to the TTGACA consensus; sequences that more closely match the TTGACA motif generally recruit RNA polymerase more efficiently, whereas greater divergence can reduce transcription. Some promoters feature deviations from TTGACA or extended -35 elements that include additional nucleotides upstream which interact with sigma factor region 4, thereby modulating recognition.

TTGACA is a canonical motif used in studies of bacterial transcription initiation and in computational promoter prediction and genome annotation. While common in many bacteria, the exact -35 consensus can vary among taxa, and archaeal/eukaryotic promoters involve different promoter elements and transcription factors.