title: Nature of the genome of the saprophytic spirochete Spirochaeta aurantia and its ribosomal RNA operons.
abstract: Using restriction endonucleases DraI, AseI, and I-CeuI in conjunction with pulsed-field gel electrophoresis, we have shown that Spirochaeta aurantia M1 possesses a circular 3.98-Mb genome. This is the second largest spirochete chromosome yet analyzed. The observation that the latter enzyme cuts in 3 places suggests the presence of 3 copies of the large subunit (23S) rRNA gene (rrl), which was confirmed by Southern hybridizations. The complete sequence of 2 of the ribosomal RNA operons was determined, revealing that their structure resembled that of the typical member of the bacterial superkingdom: rrs (16S; 1561 bp), tRNA, rrl (23S; 2972 bp), and rrf (5S; 110 bp). The S. aurantia rrs-rrl intergenic regions, as with Treponema denticola, contain genes specifying a 73-nt tRNA(Ala) (anticodon TGC) and a 77-nt tRNA(Ile) (anticodon GAT).
authors.affiliation: Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: McLaughlin
authors.forename: David M
authors.initials: DM
authors.lastname: Secko
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Paul
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Kropinski
mesh_terms: D001483:Base Sequence; D004269:DNA, Bacterial / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis; D016521:Electrophoresis, Gel, Pulsed-Field; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D013142:Spirochaeta / Q000235:genetics*; D012407:rRNA Operon / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal