Part:BBa_K3735001

Coding sequence

SefA is a protein from Thaurea selenatis (a β-proteobacteria) with a size of 94.5kDa. In the process of degrading selenite, the decrease of selenite will cause the accumulation of Se⁰ in the cell, and SefA is the substance that wraps Se⁰ in Thaurea selenatis to forms SeNPs, and transport SeNPs out of the cell. But in Escherichia coli BL21, we found that SefA will only help form SeNPs and will not participate in transshipment. In our detection, we found that SeNPs are about 300nm, which is consistent with the result in the literature. In our concentration gradient experiments, we found that strains expressing more SefA grew better, which also proved that SefA can improve the resistance of bacteria to selenite at a certain extent.

SefA is a protein from Thaurea selenatis (a β-proteobacteria).During selenate respiration by Thaurea selenatis, the reduction of selenate results in the formation of intracellular selenium (Se) deposits that are ultimately secreted as Se nanospheres. Studies have found that SefA is closely related to the deposition of elemental selenium. Then the gene was cloned and expressed in Escherichia coli. The gene sequence of this part was obtained from NCBI and its GenBank Accession number is: HQ380173.1.

In order to characterize the quality of SeNPs produced by protein SefA, the scanning electron microscope(SEM) experiment was carried out. Fig.1 showed the sizes of SeNPs produced by SefA with different strength of promoters were diversed. According to the literature, the particle size between 100-300nm has the best bioactivity. So we chose the “Low” sefA (BBa_K3735004) and “Low” ssuE tandem circuit to produce SeNPs.

Fig.1 SEM results of SeNPs production by different expression intensity of SefA. The size of SeNPs produced by middle and high expression intensity of SefA were more than 300nm and the one in low intensity was between 100-300nm.

Sequence and Features

Assembly Compatibility:

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

  Illegal BglII site found at 1476
  Illegal BglII site found at 2793
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  INCOMPATIBLE WITH RFC[25]

  Illegal NgoMIV site found at 268
  Illegal NgoMIV site found at 583
  Illegal NgoMIV site found at 709
  Illegal NgoMIV site found at 1090
  Illegal NgoMIV site found at 1513
  Illegal NgoMIV site found at 2614
  Illegal NgoMIV site found at 2863
  Illegal AgeI site found at 610
  Illegal AgeI site found at 1156
  Illegal AgeI site found at 1312
  Illegal AgeI site found at 1453
  Illegal AgeI site found at 1876
  Illegal AgeI site found at 2233
  Illegal AgeI site found at 2404
  
• 1000
  COMPATIBLE WITH RFC[1000]