ISOLATION OF BORRELIA-BURGDORFERI GENES ENCODING HOMOLOGS OF DNA-BINDING PROTEIN HU AND RIBOSOMAL-PROTEIN S20

Linear DMA with covalently closed ends is the predominant form of DNA in the spirochaete Borrelia burgdorferi. All bacteria examined to date have small DNA-binding proteins related to the Escherichia coli IHF a nd HU proteins that appear to play roles in DNA compaction and replica tion, but such proteins had not been isolated from bacteria with linea r genomes. We found a single gene in B. burgdorferi (named hbb) whose product (named Hbb) complements the defects for lambda DNA packaging f ound in E. coli strains mutant in the genes for IHF and HU. The sequen ce of the predicted B. burgdorferi protein is similar to those of HU a nd IHF-like proteins in other bacteria. The gene appears to be in an o peron with the order rpsT-hbb-orfH, where the rpsT gene is a homologue of the E. coli gene encoding ribosomal protein S20 and the orfH gene encodes a protein of unknown function. This operon is located upstream of the previously identified B. burgdorferi rho homologue.