Part:BBa_K4307007

NisK

Originated from Lactococcus lactis subsp. Lactis, NisK is a member of the two-component regulatory system NisK/NisR involved in the regulation of the biosynthesis of lantibiotic nisin. NisK functions as a membrane-associated protein kinase that phosphorylates NisR in response to environmental nisin signals. We managed to express NisK in E.coli strain.
Functioned together with NisR(BBa_K4307008), PnisA(BBa_K4307009), J23100 and EGFP, it forms composite part J23100-nisK-nisR+PnisA-EGFP(BBa_K4307013) to express fluorescence signal induced by nisin.

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]

Characterization

The following figure demonstrates our successful construction.

Figure 1: The construction results of NisK.

Fluorescence location assay was done to characterize the biobrick.

To determine whether the constitutively expressed NisK in our system could locate on cell membrane correctly, we design NisK-EGFP fusion protein, expressed the protein in MACH1-T1 strain and examined its cellular location under confocal laser scanning microscope. The imaging result showed stronger fluorescence signal located on bacterial membrane, and fluorescence intensity measured by computer also showed the same distribution(Figure 2), indicating that most NisK-EGFP fusion proteins were located correctly on the membrane.

Figure 2: NisK localization under confocal laser scanning microscope.

Conclusion

According to the location assay data, it can be found that NisK can locate on membrane correctly in E.coli, which indicates that it can act as a membrane receptor to sense nisin signal functionally in E.coli as in Lactococcus lactis. This ensures the effectiveness of nisin TCS in E.coli