Difference between revisions of "Part:BBa K2739000"

Revision as of 22:25, 8 October 2018

ProR-PhaR (The phasin autoregulation system with native promoter)

phaR is the core member of the phasin autoregulation system, which contribute to the PHA operon and PHA production. phasin is a low-molecular weight protein that plays a role in PHA granule formation by physically binding to the PHA granule surface and promote the PHA production. The expression of phasin is repressed by an autoregulator phaR, which is able to bind to the region of phasin promoter and its own promoter to regulate the expression of phasin and itself. Otherwise, phaR can also bind to the PHB granules. It is potential to help cells saving energy by curtailing excessive expression of PHA biosynthesis pathways.

Usage and Biology

According to previous research (Pötter et al, 2002), phaR binds at two sites upstream of phaP. One site is the transcriptional initiation site plus the -10 region. The other site is a region just upstream of the -35 region of the σ70 promoter of phaP. Gene of phaR was also recognised to bind to 86 bp upstream of the start codon in the open reading frame (ORF) of phaR. In addition, PhaR was detected binding on the surface of PHA granules(Pötter et al, 2002; Yamada et al, 2013). Based on the binding behaviours and following influence, it was confirmed that phaR regulated not only phaP but also itself precisely (Pötter et al, 2002).

During the later stages of PHA accumulation, PhaR leaves the PHA granules as the surface of PHA granules is mostly covered with phasin. The replaced PhaR returns to bind to the phaP promoter and represses transcription of phasin again. PhaR has been reported to autoregulate the expression of itself by binding on its promoter(Yamada et al, 2013).This autoregulation system guarantees the efficient expression of phasin as well as curtailing excessive expression of the PHA biosynthetic pathway, decreasing the metabolic burden imposed on cells.

Sequence and Features