GLYCOLYTIC ENZYME OPERON OF BORRELIA-BURGDORFERI - CHARACTERIZATION AND EVOLUTIONARY IMPLICATIONS

The genes encoding three enzymes of the glycolytic pathway have been i dentified and sequenced completely in Borrelia burgdorferi sensu stric to and partially in B. hermsii. They are clustered on the chromosome i nto an operon with a single putative promoter and are arranged downstr eam of this promoter in the following order: gadph (glyceraldehyde-3-p hosphate dehydrogenase), pgk (phosphoglycerate kinase), and tpi (trios ephosphate isomerase). gapdh and pgk are separated by 19 bp of interge nic sequence and pgk and tpi are separated by only 1 bp. Each of the t hree genes contains a putative RBS 6-7 bp upstream of each respective translational (ATG) start codon. The deduced protein encoded by gapdh consists of 335 amino acids (aa) with a predicted MW of 36 400, that o f pgk is 393 aa (MW of 42 156) and that of tpi is 290 aa (MW of 27 683 ). The aa sequences of each of the three enzymes share 58.4% (GAPDH), 52.8% (PGK) and 46.1% (TPI) identity with respective enzymes from othe r prokaryotic organisms. Phylogenetic analyses based on these universa l and conserved proteins support the hypothesis that spirochetes are a n ancient and distinct eubacterial phylum.