Expression of Shewanella oneidensis MR-1 [FeFe]-Hydrogenase Genes in Anabaena sp. Strain PCC 7120 |
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| Authors: | Katrin G?rtner Sigal Lechno-Yossef Adam J. Cornish C. Peter Wolk Eric L. Hegg |
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| Affiliation: | aGreat Lakes Bioenergy Research Center;bDepartment of Biochemistry & Molecular Biology;cMSU-DOE Plant Research Laboratory;dDepartment of Plant Biology, Michigan State University, East Lansing, Michigan, USA |
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| Abstract: | H2 generated from renewable resources holds promise as an environmentally innocuous fuel that releases only energy and water when consumed. In biotechnology, photoautotrophic oxygenic diazotrophs could produce H2 from water and sunlight using the cells'' endogenous nitrogenases. However, nitrogenases have low turnover numbers and require large amounts of ATP. [FeFe]-hydrogenases found in other organisms can have 1,000-fold higher turnover numbers and no specific requirement for ATP but are very O2 sensitive. Certain filamentous cyanobacteria protect nitrogenase from O2 by sequestering the enzyme within internally micro-oxic, differentiated cells called heterocysts. We heterologously expressed the [FeFe]-hydrogenase operon from Shewanella oneidensis MR-1 in Anabaena sp. strain PCC 7120 using the heterocyst-specific promoter PhetN. Active [FeFe]-hydrogenase was detected in and could be purified from aerobically grown Anabaena sp. strain PCC 7120, but only when the organism was grown under nitrate-depleted conditions that elicited heterocyst formation. These results suggest that the heterocysts protected the [FeFe]-hydrogenase against inactivation by O2. |
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