title: Leptospira spp. possess a complete haem biosynthetic pathway and are able to use exogenous haem sources.
abstract: Unlike the spirochetes Borrelia burgdorferi and Treponema pallidum, Leptospira spp. contain genes encoding the enzymes for most biosynthetic pathways. In this study, we describe the first haem biosynthetic pathway genes in the order Spirochaetales. Sequence analysis of the L. interrogans genome shows that all haem biosynthetic genes (hemA, heml, hemB, hemC, hemE, hemN, hemY and hemH) are clustered in a 15 kb region of the CII secondary chromosome. Although no hemD homologue (encoding uroporphyrinogen III synthase) was found in the genome, the L. interrogans hemC gene (encoding porphobilinogen deaminase) was able to restore uroporphyrinogen III synthase activity in an Escherichia coli Delta hemD mutant, suggesting that the L. interrogans hemC gene encodes a bifunctional enzyme. Similarly, we show that the L. interrogans hemH gene (encoding ferrochelatase, the terminal enzyme of the haem biosynthetic pathway) is able to complement a ferrochelatase-defective E. coli Delta hemH mutant. Further investigation of ferrochelatases was undertaken in both saprophytic and pathogenic species of Leptospira. Ferrochelatase activity of 2.3 +/- 0.1 nmol h-1 mg-1 (in comparison with 0.25 +/- 0.02 nmol h-1 mg-1 in E. coli) was found in membrane fractions of pathogenic and saprophytic species, suggesting that ferrochelatase is a membrane-associated protein. Leptospira biflexa allelic exchange mutants containing an inactivated hemH gene were recovered only when exogenous haemin was present. The results indicate that haem is an essential growth factor for Leptospira, and that these spirochetes are capable of both de novo synthesis or uptake of haem. This may have implications in a better understanding of the pathogenesis of Leptospira.
authors.affiliation: Unité de Bactériologie Moléculaire et Médicale, Institut Pasteur, Paris, France.
authors.forename: Rozenn
authors.initials: R
authors.lastname: Guégan
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Camadro
authors.forename: Isabelle
authors.initials: I
authors.lastname: Saint Girons
authors.forename: Mathieu
authors.initials: M
authors.lastname: Picardeau
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005294:Ferrochelatase / Q000235:genetics / Q000378:metabolism; D015723:Gene Library; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D006090:Gram-Negative Bacteria / Q000235:genetics; D006418:Heme / Q000096:biosynthesis*; D006427:Hemin / Q000378:metabolism; D011163:Hydroxymethylbilane Synthase / Q000378:metabolism; D007501:Iron / Q000378:metabolism; D007919:Leptospira / Q000145:classification / Q000235:genetics; D007921:Leptospira interrogans / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics*; D016415:Sequence Alignment; D013045:Species Specificity; D013144:Spirochaetales / Q000378:metabolism; D014576:Uroporphyrinogen III Synthetase / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D006418:Heme; D006427:Hemin; D007501:Iron; D011163:Hydroxymethylbilane Synthase; D014576:Uroporphyrinogen III Synthetase; D005294:Ferrochelatase