Part:BBa_K896000

SQR(sulfide quinone reductase),from Synechococcus sp. PCC 7002 plasmid pAQ7

 SQR introduction:

Sulfide-dependent anoxygenic photosynthesis, driven by photosystem I (PS/I) alone, among cyanobacteria was first described for Oscillatoria limnetica from Solar Lake. Later photosynthetic sulfide oxidation in O. limnetica led to the discovery of sulfide-quinone reductase (SQR; E.C.1.8.5.′), a novel enzyme that transfers electrons from sulfide into the quinone pool.

Above are sulfide-induced sulfide-Quinone Reductase with the electron transport system.

(Cohen, Y., E. Padan, and M. Shilo, Facultative anoxygenic photosynthesis in the cyanobacterium Oscillatoria limnetica. J Bacteriol, 1975. 123(3): p. 855-61.)

 Cloning of SQR gene:

SQR gene came from Synechococcus elongatus PCC7002 because the hypersaline strain S. elongatus PCC 7002, which is already sequenced, is 96% similar to O.limnetica SQR gene.

 Function analysis of SQR gene:

Method: DCMU was added in the medium to inhibit photosystem II, and therefore only sodium sulfide in the medium can provide electron for carbon photoassimilation. By creating different dilution of sodium sulfide, the more sodium sulfide was present, the better the growth of cyanobacteria was.

Results:

After establishing a H2S standard curve to quantify H2S concentration, different H2S concentration challenge SQR transformed E.coli and H2S consumption in 24hrs or 48hrs were tested. The result showed that SQR transformed E.coli consumed much more H2S compred to the blank control, Str transformed E.coli.(figure 2A,2B) Our SQR transformed E.coli depleted much more H2S in 48 hours than in 24 hours timepoint.(figure 3)

Following were results in our experiment.

Figure 2

(A)24 hrs

(B)48 hrs

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
  INCOMPATIBLE WITH RFC[1000]

  Illegal BsaI site found at 349