Part:BBa_K1100021

R0040-Aleader

The 75nt RNA sequence of ALeader contains two SD sequences (ribosome binding sites) and an anti-SD sequence (CUUC) which can complementarily pair with either of the SD sequences. In the absence of aminoglycosides, anti-SD pairs with SD2. The binding of ribosomes to SD1 triggers the translation of a small peptide which stops at the stop codon ahead of SD2, therefore inhibits the translation of the gene after SD2. When aminoglycosides (kanamycin for example) exists, it will induce a structural change of Aleader. The anti-SD sequence pairs with SD1, consequently unmasking SD2 for ribosomal binding, which results in the translation of the following gene.

Our Aleader riboswitch demonstrates progressive induction of reporter genes in response to sublethal doses of the antibiotics. It makes sense because an antibiotic-resistant riboswitch must be able to detect low levels of antibiotics and activate the resistance mechanism before the cells are killed. Thus, Aleader turns out to be a novel translation regulatory part with high dynamic range, slight response delay and immense modification potential.

Figure 1. Induction of Aminoglycoside Resistance Genes by Leader RNA-Antibiotic Binding(Jia X et al, 2013.).

We tested the ALeader performance by measuring the fluorescence intensity of mRFP1 when different concentrations of kanamycin sulfate are added to the bacteria culture.

Figure 2. The dose-response curve of ALeader with the promoter R0063, measured by mRFP fluorescence test.

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]