Part:BBa_K3137001

Improved RBS 4

This year, we improved the sequence of the RBS BBa_B0033, and got the RBS BBa_K3137001.

Figure1. Maps of the constructed plasmids

As we all know, RBS refers to a sputum-rich untranslated region upstream of the initiation codon AUG. BBa_B0033 is a weaker RBS based on Ron Weiss thesis. Compared with BBa_B0030, BBa_B0031, BBa_B0032, BBa_B0034, BBa_B0033 is the weakest, and whose RBS strength is 0.35% of BBa_B0034. By analyzing their sequence, we found that BBa_B0033 has fewer purines and no not have AAA sequence. SO we designed the RBS by adjusting the proportion of bases.

Figure2. Sequences of the original RBS and improved RBS

Then we ligated the two RBS with promotor rsmH (BBa_K3137000) and gene gfp (BBa_K3137011) and transform into E. coli BL21 to compare their green fluorescence. And take E. coli BL21 as a control. The figure below shows that BBa_K3137001 has the stronger fluorescently protein expression than BBa_B0033, that means it’s efficient to increase the protein expression by increasing the number of purines in the RBS sequence, which is beneficial to the binding of ribosomes.

Figure3. Expression of gfp driven by BBa_K3137001, BBa_B0033 and control

Figure4. Fluorescence intensity of gfp driven by BBa_K3137001, BBa_B0033 and control

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]