The gene for the major carbon fixation enzyme in picocyanobacteria (rbcL) has been shown to be contained in a conserved operon, which we have termed the rbcL genomic environment. To understand genomic arrangements of carbon fixation genes we have made large insert libraries from the Gulf of Mexico and the LEO-15 site off Tuckerton, NJ. These were BAC libraries made from concentration of 200 L seawater and suspending the cells in agar plugs. After proteinase K and lysozyme treatment, the DNA-containing plugs were partially digested with HindIII, the desired mw bands excised and cloned into Epicentre's pIndigoBAC vectors.
The resulting 3200 clone library from the Gulf of Mexico was screened for rbcL-containing inserts using form I, form II, and formIII/IV probes. Ten clones hybridized (dots are in duplicate, the two circled ones were identical). Eight were sequenced by DOE JGI (Paul Richardson). All clones were derived from naturally occurring marine Synechococcus.
The sequences compared to Synechococcus WH8102 appear below.
These results show that there is tremendous conservation of synteny in the immediate rbcL genomic environment, and that insertion of genes that expand the metabolic capacity can occur outside these areas of high conservation.