Difference between revisions of "Part:BBa K4451010"

Revision as of 15:47, 12 October 2023

T4 AsiA

BBa_K4451010 encodes the AsiA protein from the T4 phage. This protein has been reported to interact with sigma-70 factor and inhibits recognition of sigma-70 promoters (Ouhammouch et al., 1995).

Description

A transcriptional inhibitor from T4 phage, which causes growth rate suppression in E. coli. The AsiA gene encodes an anti-σ factor, which is able to bind to σ70 and prevent the RNA polymerase σ70 holoenzyme from recognising σ70 specific promoters, thus enacting a transcriptional downregulation of housekeeping genes and subsequently causing growth rate suppression. AsiA further enables the transcription of phage middle genes as part of the T4 infection cycle (J. Liu et al., 2004).

Figure 1: Mean log2(OD) against time for AsiA, concentrations refer to the [IPTG] used to induce the pLac promoter regulating AsiA.

Figure 1 shows that there's a significant decrease in growth of E. coli when they are transformed with a plasmid containing AsiA. The decreased mean log 2 OD observed without induction of pLac shows leaky expression of the growth slower gene has an impact on bacterial cell growth. With induction, the greater the [IPTG], there's a large decrease in growth rate between 4uM and 1000uM AsiA, suggesting that in the future more [IPTG] need to be used between this interval. This supports that AsiA causes a growth slowing impact in E. coli, and the level of growth slowing can be controlled using an inducible promoter.

Sequence and Features