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.

Figure 1

Function analysis of SQR gene:

Abstract Several Cyanobacteria have Sulfide-Quinone Reductase (SQR) and thus the ability to deprive electron from sulfide compound. According to both databases of NCBI and KEGG, the sqr in Synechococcus SP. PCC 7002 shared great similarity with that of Oscillatoria limnetica, which is reported to exhibit anoxygenic photosynthesis by consumed sulfide anion. Since we planned to express sqr from Synechococcus SP. PCC 7002 in Synechococcus SP. PCC 7942 and Escherichia coli, the experiment was designed to testify the property of the sqr. 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, we expected that the more sodium sulfide was present, the better the cell grew.

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. Our SQR transformed E.coli depleted much more H2S in 48 hours than in 24 hours timepoint.(figure 2A,2B) And SQR transformed E.coli consumed H2S dramatically.(figure 3)

Following were results in our experiment.

Figure 2

(A)different concentration of H2S under 24 hrs

(B)different concentration of H2S under 48 hrs

Figure 3

Conclusion

Our cloning product SQR(sulfide quinone reductase),from Synechococcus sp. PCC 7002 plasmid pAQ7, could transfer electrons from sulfide into the quinone pool.

References

1.Facultative Anoxygenic Photosynthesis in the Cyanobacterium Oscillatoria limnetica YEHUDA COHEN,* ETANA PADAN, AND MOSHE SHILO Department of Microbiological Chemistry, The Hebrew University-Hadassah Medical School, Jerusalem, Israel Received for publication 9 May 1975

2.Sulfide oxidation in gram-negative bacteria by expression of the sulfide–quinone reductase gene of Rhodobacter capsulatus and by electron transport to ubiquinone Hiroomi Shibata and Shigeki Kobayashi 2001

3.Sulfur metabolism in Thiorhodoceae. I. Quantitative measurements on growing cells of Chromatium okenii. Antonie Leeuwenhoek, 30: 225–238 Trüper, H.G., and Schlegel, H.G. 1964.

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