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Loss of Homogentisate 1,2-Dioxygenase Activity in Bacillus anthracis Results in Accumulation of Protective Pigment.

Han H, Iakovenko L, Wilson AC - PLoS ONE (2015)

Bottom Line: In Bacillus anthracis, loss of hmgA, encoding homogentisate 1,2-dioxygenase, results in accumulation of a melanin-like pigment called pyomelanin.Pyomelanin is produced in the mutant as a byproduct of disrupted catabolism of L-tyrosine and L-phenylalanine.Neither loss of hmgA nor accumulation of pyomelanin alter virulence gene expression, sporulation or germination.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Georgia State University, Atlanta, GA, United States of America.

ABSTRACT
Melanin production is important to the pathogenicity and survival of some bacterial pathogens. In Bacillus anthracis, loss of hmgA, encoding homogentisate 1,2-dioxygenase, results in accumulation of a melanin-like pigment called pyomelanin. Pyomelanin is produced in the mutant as a byproduct of disrupted catabolism of L-tyrosine and L-phenylalanine. Accumulation of pyomelanin protects B. anthracis cells from UV damage but not from oxidative damage. Neither loss of hmgA nor accumulation of pyomelanin alter virulence gene expression, sporulation or germination. This is the first investigation of homogentisate 1,2-dioxygenase activity in the Gram-positive bacteria, and these results provide insight into a conserved aspect of bacterial physiology.

No MeSH data available.


Related in: MedlinePlus

Pigment production in cell-free extracts.Cell-free extracts from cells grown in LB at 37°C for 6 hours. Amino acids then added to cell-free extracts, as indicated, and incubated for an additional 24 hours at 37°C. 1, 34F2, no added amino acids; 2, 34F2 with L-tyrosine; 3, 34F2 with L-phenylalanine; 4, 34F2 with L-tryptophan; 5, AW-A127 (ΔhmgA), no added amino acids; 6, AW-A127 with L-tyrosine; 7, AW-A127 with L-phenylalanine; 8, AW-A127 with L-tryptophan.
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pone.0128967.g005: Pigment production in cell-free extracts.Cell-free extracts from cells grown in LB at 37°C for 6 hours. Amino acids then added to cell-free extracts, as indicated, and incubated for an additional 24 hours at 37°C. 1, 34F2, no added amino acids; 2, 34F2 with L-tyrosine; 3, 34F2 with L-phenylalanine; 4, 34F2 with L-tryptophan; 5, AW-A127 (ΔhmgA), no added amino acids; 6, AW-A127 with L-tyrosine; 7, AW-A127 with L-phenylalanine; 8, AW-A127 with L-tryptophan.

Mentions: To confirm these findings, pigment production was tested in cell-free extracts of the parental and mutant strains. 34F2 and the ΔhmgA strains were grown to early-stationary phase at 37°C in LB, cells disrupted by sonication, and cell debris removed by filtration. Amino acids were then added to the cell-free extracts and incubated for 48 hours at 37°C. With extracts of the parental strain, pigment was not produced under conditions tested (Fig 5). In extracts of the ΔhmgA strain, pigment was observed with the addition of exogenous L-tyrosine or L-phenylalanine but not with the addition of exogenous L-tryptophan. Combined, these findings indicate that, in the ΔhmgA strain, pyomelanin is produced in the presence of L-tyrosine and L-phenylalanine.


Loss of Homogentisate 1,2-Dioxygenase Activity in Bacillus anthracis Results in Accumulation of Protective Pigment.

Han H, Iakovenko L, Wilson AC - PLoS ONE (2015)

Pigment production in cell-free extracts.Cell-free extracts from cells grown in LB at 37°C for 6 hours. Amino acids then added to cell-free extracts, as indicated, and incubated for an additional 24 hours at 37°C. 1, 34F2, no added amino acids; 2, 34F2 with L-tyrosine; 3, 34F2 with L-phenylalanine; 4, 34F2 with L-tryptophan; 5, AW-A127 (ΔhmgA), no added amino acids; 6, AW-A127 with L-tyrosine; 7, AW-A127 with L-phenylalanine; 8, AW-A127 with L-tryptophan.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4457819&req=5

pone.0128967.g005: Pigment production in cell-free extracts.Cell-free extracts from cells grown in LB at 37°C for 6 hours. Amino acids then added to cell-free extracts, as indicated, and incubated for an additional 24 hours at 37°C. 1, 34F2, no added amino acids; 2, 34F2 with L-tyrosine; 3, 34F2 with L-phenylalanine; 4, 34F2 with L-tryptophan; 5, AW-A127 (ΔhmgA), no added amino acids; 6, AW-A127 with L-tyrosine; 7, AW-A127 with L-phenylalanine; 8, AW-A127 with L-tryptophan.
Mentions: To confirm these findings, pigment production was tested in cell-free extracts of the parental and mutant strains. 34F2 and the ΔhmgA strains were grown to early-stationary phase at 37°C in LB, cells disrupted by sonication, and cell debris removed by filtration. Amino acids were then added to the cell-free extracts and incubated for 48 hours at 37°C. With extracts of the parental strain, pigment was not produced under conditions tested (Fig 5). In extracts of the ΔhmgA strain, pigment was observed with the addition of exogenous L-tyrosine or L-phenylalanine but not with the addition of exogenous L-tryptophan. Combined, these findings indicate that, in the ΔhmgA strain, pyomelanin is produced in the presence of L-tyrosine and L-phenylalanine.

Bottom Line: In Bacillus anthracis, loss of hmgA, encoding homogentisate 1,2-dioxygenase, results in accumulation of a melanin-like pigment called pyomelanin.Pyomelanin is produced in the mutant as a byproduct of disrupted catabolism of L-tyrosine and L-phenylalanine.Neither loss of hmgA nor accumulation of pyomelanin alter virulence gene expression, sporulation or germination.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Georgia State University, Atlanta, GA, United States of America.

ABSTRACT
Melanin production is important to the pathogenicity and survival of some bacterial pathogens. In Bacillus anthracis, loss of hmgA, encoding homogentisate 1,2-dioxygenase, results in accumulation of a melanin-like pigment called pyomelanin. Pyomelanin is produced in the mutant as a byproduct of disrupted catabolism of L-tyrosine and L-phenylalanine. Accumulation of pyomelanin protects B. anthracis cells from UV damage but not from oxidative damage. Neither loss of hmgA nor accumulation of pyomelanin alter virulence gene expression, sporulation or germination. This is the first investigation of homogentisate 1,2-dioxygenase activity in the Gram-positive bacteria, and these results provide insight into a conserved aspect of bacterial physiology.

No MeSH data available.


Related in: MedlinePlus