Part:BBa_K2036000

CII bacteriophage lambda trascriptional activator

CII is an important part of the bacteriophage lambda operon. It promotes lysogeny through activation of three phage promoters p(E), p(I) and p(aQ), recognizing a direct repeat sequence TTGCN6TTGC at each. It is an unstable protein in vivo, being rapidly degraded by the host protease HflB (FtsH). This instability is essential for the function of CII in the lysis-lysogeny switch. From NMR and limited proteolysis we show that about 15 C-terminal residues of CII are highly flexible, and may act as a target for proteolysis in vivo. From in vitro transcription, isothermal calorimetry and gel chromatography of CII (1-97) and its truncated fragments CIIA (4-81/82) and CIIB (4-69), we find that residues 70-81/82 are essential for (a) tetramer formation, (b) operator binding and (c) transcription activation. Presumably, tetramerization is necessary for the latter functions.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]

Protein&promoter

--CII and pRE

CII (BBa_K2036000) functions as a transcriptional activator to direct promoter RE, so we constructed CII-TT-pRE-RBS-GFP-LVAssrAtag as test group and pRE-RBS-GFPLVAssrAtag as CK to see if CII efficiently activate pRE.

Fig1: According to the Flourescence measurement curve above, we can see clearly that GFP level increasedover time and it showed significant difference from CK.

Fig2: We also did Fluorescence microscope detection after 30, 120 and 240 minutes induction.According to the figture below, we can tell qualitively that pRE leakage is at relatively low level and CII can efficiently activate the promoter.

Protein&protein reaction

We had submitted and documented RBS-CIII-RBS-CIII-RBS-CII-TT-pRE-RBS-GFP-LVAssrAtag (BBa_K2036014) and RBS-CII-RBS-CII-RBS-CII-TT-pRE-RBS-GFP-LVAssrAtag (BBa_K2036015). These two parts were to test whether CIII can protect CII from being degraded by Ftsh by competitive inhibition.

Fig3: According to the Flourescence measurement curve above, we can see clearly that GFP level of CIII test circuit increased over time and it showed significant difference from two control groups. It indicates that tandomly expressed CIII can efficiently protect CII from being degraded by Ftsh.