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Anaplasma phagocytophilum p44 mRNA Expression Is Differentially Regulated in Mammalian and Tick Host Cells: Involvement of the DNA Binding Protein ApxR
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| Zeitschriftentitel: | Journal of Bacteriology |
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| Personen und Körperschaften: | , , , , |
| In: | Journal of Bacteriology, 189, 2007, 23, S. 8651-8659 |
| Format: | E-Article |
| Sprache: | Englisch |
| veröffentlicht: |
American Society for Microbiology
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| Schlagwörter: |
| Zusammenfassung: | <jats:title>ABSTRACT</jats:title> <jats:p> The natural life cycle of <jats:italic>Anaplasma phagocytophilum</jats:italic> , an obligatory intracellular bacterium that causes human granulocytic anaplasmosis, consists of alternate infection of two distinct hosts, ticks and mammals, in which bacterial surface proteins are expected to have a critical role. The present study investigated regulation of <jats:italic>A. phagocytophilum p44</jats:italic> genes, which encode the P44 major surface proteins. Quantitative real-time reverse transcription-PCR analysis revealed that the amount of <jats:italic>p44</jats:italic> mRNA obtained from spleens of <jats:italic>A. phagocytophilum</jats:italic> -infected SCID mice was approximately 10-fold greater than the amount obtained from salivary glands of <jats:italic>A. phagocytophilum</jats:italic> -infected <jats:italic>Ixodes scapularis</jats:italic> nymphs. Similarly, the amount of <jats:italic>p44</jats:italic> mRNA obtained from <jats:italic>A. phagocytophilum</jats:italic> -infected HL-60 cells per bacterium was significantly greater than the amount obtained from infected ISE6 tick cells. The relative amount of <jats:italic>p44</jats:italic> mRNA was approximately threefold higher in <jats:italic>A. phagocytophilum</jats:italic> -infected HL-60 cells cultured at 37°C than in <jats:italic>A. phagocytophilum</jats:italic> -infected HL-60 cells cultured at 28°C. Although there are more than 100 <jats:italic>p44</jats:italic> paralogs, we observed expression mainly from the <jats:italic>p44</jats:italic> expression locus ( <jats:italic>p44E</jats:italic> ) in various host environments. Interestingly, transcription of the <jats:italic>A. phagocytophilum</jats:italic> gene encoding the DNA binding protein ApxR was also significantly greater in <jats:italic>A. phagocytophilum</jats:italic> -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 <jats:italic>p44E</jats:italic> and <jats:italic>apxR</jats:italic> . ApxR also transactivated the <jats:italic>p44E</jats:italic> and <jats:italic>apxR</jats:italic> promoter regions in a <jats:italic>lacZ</jats:italic> reporter assay. These results indicate that <jats:italic>p44</jats:italic> genes and <jats:italic>apxR</jats:italic> are specifically up-regulated in the mammalian host environment and suggest that ApxR not only is positively autoregulated but also acts as a transcriptional regulator of <jats:italic>p44E</jats:italic> . </jats:p> |
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| Umfang: | 8651-8659 |
| ISSN: |
0021-9193
1098-5530 |
| DOI: | 10.1128/jb.00881-07 |