Sulfite reduction in mycobacteria

Rachel Pinto, Joseph S. Harrison, Tsungda Hsu, William R. Jacobs, Thomas S. Leyh

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Mycobacterium tuberculosis places an enormous burden on the welfare of humanity. Its ability to grow and its pathogenicity are linked to sulfur metabolism, which is considered a fertile area for the development of antibiotics, particularly because many of the sulfur acquisition steps in the bacterium are not found in the host. Sulfite reduction is one such mycobacterium-specific step and is the central focus of this paper. Sulfite reduction in Mycobacterium smegmatis was investigated using a combination of deletion mutagenesis, metabolite screening, complementation, and enzymology. The initial rate parameters for the purified sulfite reductase from M. tuberculosis were determined under strict anaerobic conditions [kcat = 1.0 (±0.1) electron consumed per second, and Km(SO3-2) = 27 (±1) μM], and the enzyme exhibits no detectible turnover of nitrite, which need not be the case in the sulfite/nitrite reductase family. Deletion of sulfite reductase (sirA, originally misannotated nirA) reveals that it is essential for growth on sulfate or sulfite as the sole sulfur source and, further, that the nitrite-reducing activities of the cell are incapable of reducing sulfite at a rate sufficient to allow growth. Like their nitrite reductase counterparts, sulfite reductases require a siroheme cofactor for catalysis. Rv2393 (renamed che1) resides in the sulfur reduction operon and is shown for the first time to encode a ferrochelatase, a catalyst that inserts Fe2+ into siroheme. Deletion of che1 causes cells to grow slowly on metabolites that require sulfite reductase activity. This slow-growth phenotype was ameliorated by optimizing growth conditions for nitrite assimilation, suggesting that nitrogen and sulfur assimilation overlap at the point of ferrochelatase synthesis and delivery.

Original languageEnglish (US)
Pages (from-to)6714-6722
Number of pages9
JournalJournal of Bacteriology
Volume189
Issue number18
DOIs
StatePublished - Sep 2007

Fingerprint

Oxidoreductases Acting on Sulfur Group Donors
Sulfites
Mycobacterium
Sulfur
Nitrites
Ferrochelatase
Nitrite Reductases
Growth
Mycobacterium tuberculosis
Mycobacterium smegmatis
Operon
Catalysis
Mutagenesis
Sulfates
Virulence
Nitrogen
Electrons
Anti-Bacterial Agents
Bacteria
Phenotype

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Immunology

Cite this

Sulfite reduction in mycobacteria. / Pinto, Rachel; Harrison, Joseph S.; Hsu, Tsungda; Jacobs, William R.; Leyh, Thomas S.

In: Journal of Bacteriology, Vol. 189, No. 18, 09.2007, p. 6714-6722.

Research output: Contribution to journalArticle

Pinto, R, Harrison, JS, Hsu, T, Jacobs, WR & Leyh, TS 2007, 'Sulfite reduction in mycobacteria', Journal of Bacteriology, vol. 189, no. 18, pp. 6714-6722. https://doi.org/10.1128/JB.00487-07
Pinto, Rachel ; Harrison, Joseph S. ; Hsu, Tsungda ; Jacobs, William R. ; Leyh, Thomas S. / Sulfite reduction in mycobacteria. In: Journal of Bacteriology. 2007 ; Vol. 189, No. 18. pp. 6714-6722.
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