Identification of the Genomic Region Which Complements a Temperature-Sensitive, High-CO2 Requiring Mutant of the Cyanobacterium, Synechococcus PCC7942

Abstract

For the purpose of understanding the nature of inorganic carbon (Cinorg) transport system, several mutants of Synechococcus PCC7942 (Anacystis nidulans R2) that require high-CO2 concentration for growth have been isolated (1–4). A temperature-sensitive mutant, C3P-O, was reported to be impaired in concentrating Cinorg into the cells (4). However, as will be shown in the present study, the lesion caused in this mutant is rather in the ability to utilize the intracellular Cinorg pool. The genes that are defective in these mutants remain to be defined. We report here the identification of the wild type genomic region which complements the mutant, C3P-O. The genetic location of the cloned segment relative to rbcLS genes encoding subunits of ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase, and the transcription from the cloned genomic region will also be described.