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Volume 155, Issue 11

Identification and functional characterization of the iron-dependent regulator (IdeR) of subsp. Free

Abstract

subspecies (MAP), the causative agent of Johne's disease in cattle and sheep, has unique iron requirements in that it is mycobactin-dependent for cultivation . The iron-dependent regulator (IdeR) is a well-characterized global regulator responsible for maintaining iron homeostasis in (MTB). We identified an orthologous segment in the MAP genome, MAP2827, with >93 % amino acid identity to MTB IdeR. Electrophoretic mobility shift assays and DNase protection assays confirmed that MAP2827 binds the 19 bp consensus motif (iron box) on the MAP genome. Sequencing of MAP2827 from multiple isolates revealed a non-synonymous change (R91G) exclusive to sheep strains. Reporter gene assays and quantitative real-time RT-PCR assays in two diverse MAP strains and in an deletion mutant of (mc155) suggested that both sheep MAP IdeR (sIdeR) and cattle MAP IdeR (cIdeR) repress transcription at high iron concentrations and relieve repression at low iron concentrations. On the other hand, (an iron storage gene) was upregulated by cIdeR when presented with MTB or the cattle MAP promoter, and was downregulated by sIdeR in the presence of MTB, or sheep or cattle MAP promoters, at high iron concentrations. The differential iron regulatory mechanisms between IdeR-regulated genes across strains may contribute to the differential growth or pathogenic characteristics of sheep and cattle MAP strains. Taken together, our study provides a possible reason for mycobactin dependency and suggests strong implications in the differential iron acquisition and storage mechanisms in MAP.

  • Received:
  • Accepted:
  • Revised:
  • Published Online:
Keyword(s): cIdeR/sIdeR, cattle/sheep MAP IdeR , EMSA, electrophoretic mobility shift assay , MAP, Mycobacterium avium subsp. paratuberculosis and MTB, Mycobacterium tuberculosis
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2009-11-01
2024-04-19
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Identification and functional characterization of the iron-dependent regulator (IdeR) of Mycobacterium avium subsp. paratuberculosis
Microbiology 155, 3683 (2009); https://doi.org/10.1099/mic.0.031948-0
/content/journal/micro/10.1099/mic.0.031948-0
/content/journal/micro/10.1099/mic.0.031948-0
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