A requirement for phosphoenolpyruvate carboxylase in the cyanobacterium Synechococcus PCC 7942
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The gene encoding phosphoenolpyruvate carboxylase (PEPCase) in the cyanobacterium Synechococcus PCC 7942 has been isolated and characterized. As a first step in determining the role of this enzyme in cyanobacterial carbon metabolism we have attempted to generate PEPCase deficient mutants by insertional inactivation of the PEPCase gene (ppc) and recombination into the wild-type genome. Transformants generated by these constructs appear to be merodiploids in which some copies of ppc remain intact and PEPCase activity is present. Successful insertional inactivation of regions of the genome on either side of ppc suggest that the merodiploid state is a result of a requirement for PEPCase activity by the cyanobacteria. Attempts to select for ppc mutants by nutritional complementation during segregation are also described.
Key wordsCyanobacteria Synechocccus PEPCase gene inactivation merodiploid carbon metabolism
gene coding for PEPCase
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