Difference between revisions of "Part:BBa K731040"

Revision as of 20:44, 26 September 2012

Inducible araC-pBAD promoter regulating a sfGFP-tagged M256I CysE

A sfGFP tagged M256I CysE inducible by arabinose. This part was subcloned and characterized in pSB3C5.

This part is also available in pSB3C5. Please contact igemtrento[at]gmail.dot.com if you are interested in this part.

Usage and Biology

CysE is a serine acetyltransferase that mediates the production of cysteine. More specifically, CysE catalyses the activation of L-serine by acetyl-CoA. Its product, 0-acetyl-L-serine (OAS), is then subsequently converted to L-cysteine by 0-acetyl-L-serine(thio1)lyase. Normally,the catalytic activity of CysE is sensitive to feedback inhibition by L-cysteine, but this is a mutated version (M256I) that have a 10-fold decrease in feedback inhibition by cysteine itself.

FIGURE 1. CysE-sfGFP expression with different concentrations of arabinose, after 4 hours of induction.
Test was conducted in NEB10beta strain, with part BBa_K731240 in pSB3C5. Cells were grown in LB broth until OD_600= 0.3 then centrifuged and resuspended in equal amount of minimal MOPS A medium (with 60mM glycerol as carbon source) and induced at OD_600 = 0.6 with 5mM arabinose. Higher CysE-sfGFP expression is observed as the arabinose concentration increases. However, MOPS medium seem to negatively influence induction, delaying promoter response to higher arabinose concentration. No difference in fluorescence intensity between not induced and control NEB10beta cells was observed.

FIGURE 2. CysE-sfGFP expression with different concentrations of arabinose in presence or absence of glucose.
Test was conducted in NEB10beta strain, with part BBa_K731240 in pSB3C5. This chart shows the difference in expression levels when using glucose or glycerol as carbon source. MOPS A has 60mM glycerol as carbon source, MOPS B has 30mM glucose. Data relative to MOPS A are shown in orange, the ones relative MOPS B are in blue. Expression levels in MOPS B with 5mM arabinose are very similar to levels in MOPS A with 0.1mM arabinose.

FIGURE 3. CysE-sfGFP expression over time, after induction.
Test was conducted in NEB10beta strain, with part BBa_K731250 in pSB3C5. Cells were grown in LB broth until OD_600= 0.3 then centrifuged and resuspended in equal amount of minimal MOPS media (A or B, in orange and blue respictively) and induced at OD_600 = 0.6 with 5mM arabinose.In absence of glucose, increasing linear expression over time of GFP is observed, while in MOPS B, in presence of glucose, expression levels are much lower.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  INCOMPATIBLE WITH RFC[21]

  Illegal BamHI site found at 1144
  Illegal BamHI site found at 2045
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  INCOMPATIBLE WITH RFC[25]

  Illegal AgeI site found at 979
  Illegal AgeI site found at 1909
  
• 1000
  INCOMPATIBLE WITH RFC[1000]

  Illegal SapI site found at 961
  Illegal SapI.rc site found at 2075