title: An inverted repeat in the ospC operator is required for induction in Borrelia burgdorferi.
abstract: Borrelia burgdorferi, the spirochete that causes Lyme disease, differentially regulates synthesis of the outer membrane lipoprotein OspC to infect its host. OspC is required to establish infection but then repressed in the mammal to avoid clearance by the adaptive immune response. Inverted repeats (IR) upstream of the promoter have been implicated as an operator to regulate ospC expression. We molecularly dissected the distal inverted repeat (dIR) of the ospC operator by site-directed mutagenesis at its endogenous location on the circular plasmid cp26. We found that disrupting the dIR but maintaining the proximal IR prevented induction of OspC synthesis by DNA supercoiling, temperature, and pH. Moreover, the base-pairing potential of the two halves of the dIR was more important than the nucleotide sequence in controlling OspC levels. These results describe a cis-acting element essential for the expression of the virulence factor OspC.
authors.affiliation: Division of Biological Sciences, The University of Montana, Missoula, Montana, United States of America.
authors.forename: Dan
authors.initials: D
authors.lastname: Drecktrah
authors.forename: Laura S
authors.initials: LS
authors.lastname: Hall
authors.forename: Laura L
authors.initials: LL
authors.lastname: Hoon-Hanks
authors.forename: D Scott
authors.initials: DS
authors.lastname: Samuels
mesh_terms: D000942:Antigens, Bacterial / Q000737:chemistry / Q000235:genetics*; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D025065:Borrelia burgdorferi / Q000235:genetics* / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D023061:Gene Order; D055029:Inverted Repeat Sequences; D008969:Molecular Sequence Data; D009875:Operator Regions, Genetic; D014176:Protein Biosynthesis; D013696:Temperature
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D004269:DNA, Bacterial; C079616:OspC protein