f Differential activity of Rickettsia rickettsii ompA and ompB promoter regions in a heterologous reporter gene system
- Authors: Paul F. Policastro, Ted Hackstadt
- Author for correspondence: Paul F. Policastro. Tel: +1 406 363 9343. Fax: +1 406 363 9204. e-mail: firstname.lastname@example.org
- Microbiology, November 1994 140: 2941-2949, doi: 10.1099/13500872-140-11-2941
- Subject: Genetics And Molecular Biology
- Published Online:
The outer membrane of the Gram-negative obligate intracellular parasite Rickettsia rickettsii contains two large surface protein antigens with approximate molecular masses of 200 and 135 kDa termed rOmpA and rOmpB, respectively. rOmpB is the most abundant protein in the outer membrane, while rOmpA is a relatively minor constituent. Densitometry of intrinsically radiolabelled protein profiles from R. rickettsii-infected Vero cells indicated a molar ratio of approximately 1:9 between rOmpA and rOmpB. The putative promoter-5′ untranslated regions (5′ UTR) from their recently characterized genes (rompA and rompB) were placed in the promoter assay vector pKK232-8 to test whether these elements conserve aspects of differential expression in a heterologous host-reporter system. Primer extension analysis of RNA from Escherichia coli clones containing the constructs indicated that E. coli RNA polymerase faithfully utilizes rompA and rompB transcription start sites identified previously in R. rickettsii. The rompB insert directs 28-fold higher levels of chloramphenicol acetyl transferase activity than the rompA insert.
The GenBank accession numbers for the sequence data reported in this paper are M84167 (rompB) and M84168 (rompA).
- Keyword(s): Rickettsia rickettsii, α-proteobacteria, transcription, promoter, outer membrane proteins
© Society for General Microbiology 1994 | Published by the Society for General Microbiology
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