Regulation of Heme Biosynthesis in Escherichia coli

Woodard, Steven I.; Dailey, Harry A.

doi:10.1006/abbi.1995.1016

Cited by 81 publications

(54 citation statements)

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“…Thus, heme synthesis is limiting, but we note that the use of heme sinks such as periplasmic or cytoplasmic cytochrome b 5 can increase the total heme synthesis in the cell. This is in agreement with a recent report on heme synthesis in the E. coli cytoplasm (45).…”

Section: Discussionsupporting

confidence: 94%

Use of heme reporters for studies of cytochrome biosynthesis and heme transport

1996

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Strains of Escherichia coli containing mutations in the cydDC genes are defective for synthesis of the heme proteins cytochrome bd and c-type cytochromes. The cydDC genes encode a putative heterodimeric ATP-binding cassette transporter that has been proposed to act as an exporter of heme to the periplasm. To more fully understand the role of this transporter (and other factors) in heme protein biosynthesis, we developed plasmids that produce various heme proteins (e.g., cytochrome b 5 , cytochrome b 562 , and hemoglobin) in the periplasm of E. coli. By using these reporters, it was shown that the steady-state levels of polypeptides of heme proteins known to be stable without heme (e.g., cytochrome b 5 and hemoglobin apoprotein) are significantly reduced in a cydC mutant. Exogenous addition of hemin to the cydC mutant still resulted in <10% of wild-type steady-state levels of apohemoglobin in the periplasm. This locus was shown to be essential in E. coli for endogenous cytochrome c biogenesis but not cytochrome b 562 synthesis. Consistent with these and previous results, it is proposed that the HelABC transporter is specifically involved in heme export for ligation (hel). This class of periplasmic cytochromes is proposed to require heme liganding before undergoing correct folding.

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Section: Discussionsupporting

confidence: 94%

Use of heme reporters for studies of cytochrome biosynthesis and heme transport

1996

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“…Since ALA-induced reactive oxygen acts on the guanine base of DNA, ALA can be a mutagenic compound. Therefore, intracellular ALA concentrations are strictly regulated (42,44). In this study, we examined the intracellular ALA concentrations in the wild-type and tolC mutant cells grown in the presence of ALA; however, no significant differences in the intracellular ALA concentration were noted between the wild-type and tolC mutant cells.…”

Section: Discussionmentioning

confidence: 94%

TolC-Dependent Exclusion of Porphyrins in Escherichia coli

Tatsumi

Wachi

2008

J Bacteriol

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We found that Escherichia coli tolC mutants showed increased sensitivity to 5-aminolevulinic acid (ALA), a precursor of porphyrins. The tolC mutant cells grown in the presence of ALA showed a reddish brown color under visible light and a strong red fluorescence under near-UV irradiation. Fluorescence spectrometry and high-performance liquid chromatography analysis showed that the tolC mutant cells grown in the presence of ALA accumulated a large amount of coproporphyrin(ogen) intracellularly. In contrast, the wild-type cells produced coproporphyrin extracellularly. The tolC mutant cells grown in the presence of ALA, which were capable of surviving in the dark, were killed by near-UV irradiation, suggesting that the intracellular coproporphyrin(ogen) renders these cells photosensitive. These results suggest that the TolC-dependent efflux system is involved in the exclusion of porphyrin(ogen)s in E. coli.

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“…Either protein, when overexpressed, promotes PPIX accumulation, an intermediate in the heme biosynthetic pathway. This could be the result of a higher heme biosynthetic activity due to a reduced intracellular heme pool (19,20). To challenge this hypothesis, YfeX and EfeB activities were tested with meso-heme, a nonnatural porphyrin.…”

Section: Discussionmentioning

confidence: 99%

Bacteria capture iron from heme by keeping tetrapyrrol skeleton intact

Létoffé

Heuck

Delepelaire

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

131

126

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Because heme is a major iron-containing molecule in vertebrates, the ability to use heme-bound iron is a determining factor in successful infection by bacterial pathogens. Until today, all known enzymes performing iron extraction from heme did so through the rupture of the tetrapyrrol skeleton. Here, we identified 2 Escherichia coli paralogs, YfeX and EfeB, without any previously known physiological functions. YfeX and EfeB promote iron extraction from heme preserving the tetrapyrrol ring intact. This novel enzymatic reaction corresponds to the deferrochelation of the heme. YfeX and EfeB are the sole proteins able to provide iron from exogenous heme sources to E. coli. YfeX is located in the cytoplasm. EfeB is periplasmic and enables iron extraction from heme in the periplasm and iron uptake in the absence of any heme permease. YfeX and EfeB are widespread and highly conserved in bacteria. We propose that their physiological function is to retrieve iron from heme

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Regulation of Heme Biosynthesis in Escherichia coli

Cited by 81 publications

References 0 publications

Use of heme reporters for studies of cytochrome biosynthesis and heme transport

Use of heme reporters for studies of cytochrome biosynthesis and heme transport

TolC-Dependent Exclusion of Porphyrins in Escherichia coli

Bacteria capture iron from heme by keeping tetrapyrrol skeleton intact

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