This Article Full Text (PDF) Other Versions of this Article: JB.00881-07v1 189/23/8651    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wang, X. Articles by Rikihisa, Y. Search for Related Content PubMed PubMed Citation Articles by Wang, X. Articles by Rikihisa, Y.

 Previous Article  |  Next Article 

J. Bacteriol. doi:10.1128/JB.00881-07
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Anaplasma phagocytophilum p44 mRNA Expression is Differentially Regulated in Mammalian and Tick Host Cells: Involvement of the DNA Binding Protein ApxR

Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210

^* To whom correspondence should be addressed. Email: rikihisa.1{at}osu.edu.

	Abstract

The natural life cycle of Anaplasma phagocytophilum, an obligatory intracellular bacterium that causes human granulocytic anaplasmosis, consists of alternate infection of two distinct hosts, ticks and mammals, where bacterial surface proteins are expected to have a critical role. The present study investigated regulation of A. phagocytophilum p44s, which encode the P44 major surface proteins. Quantitative real time RT-PCR analysis revealed that the relative amount of p44 mRNA from spleens of A. phagocytophilum-infected SCID mice was approximately 10-fold greater than from salivary glands of A. phagocytophilum-infected Ixodes scapularis nymphs. Similarly, the amount of p44 mRNA from A. phagocytophilum-infected HL-60 cells per bacterium was significantly greater than from infected ISE6 tick cells. The relative amount of p44 transcripts was approximately 3-fold higher in A. phagocytophilum-infected HL-60 cells cultured at 37°C than at 28°C. Although there are more than 100 p44 paralogs, we mainly observed expression from the p44-expression locus (p44E) in various host environments. Interestingly, transcription of the A. phagocytophilum gene encoding the DNA binding protein ApxR was also significantly greater in A. phagocytophilum-infected HL-60 cells than in infected ISE6 tick cells. Gel mobility shift and DNase I protection assays revealed recombinant ApxR binding to the promoter regions of p44E and apxR. ApxR also transactivated the p44E and apxR promoter regions in a lacZ reporter assay. These results indicate that p44s and apxR are specifically upregulated in the mammalian host environment and suggest that ApxR is not only positively autoregulated, but also acts as a transcriptional regulator of p44E.

This article has been cited by other articles:

• Cheng, Z., Wang, X., Rikihisa, Y. (2008). Regulation of Type IV Secretion Apparatus Genes during Ehrlichia chaffeensis Intracellular Development by a Previously Unidentified Protein. J. Bacteriol. 190: 2096-2105 [Abstract] [Full Text]  
• Scorpio, D. G., Leutenegger, C., Berger, J., Barat, N., Madigan, J. E., Dumler, J. S. (2008). Sequential Analysis of Anaplasma phagocytophilum msp2 Transcription in Murine and Equine Models of Human Granulocytic Anaplasmosis. CVI 15: 418-424 [Abstract] [Full Text]