The Propionibacterium freudenreichii hemYHBXRL gene cluster, which encodes enzymes and a regulator involved in the biosynthetic pathway from glutamate to protoheme

Appl Microbiol Biotechnol. 1997 Apr;47(4):385-92. doi: 10.1007/s002530050945.


A clone that can complement both Escherichia coli hemB and hemL mutations was found among plasmids containing the Propionibacterium freudenreichii hemB gene, which encodes delta-aminolevulinic acid dehydratase. The regions upstream and downstream of the hemB gene were sequenced. Two open-reading frames (ORF1 and -2), which were similar to the hemY gene encoding protoporphyrinogen oxidase and the hemH gene encoding ferrochelatase from Bacillus subtilis, were found upstream of the hemB gene. ORF1 and -2 complemented the E. coli hemG mutation, defective in protoporphyrinogen oxidase, and the hemH gene respectively. Since ORF1 had no homology to hemG, the gene was designated hemY. The hemYHB genes appeared to be within the same transcription unit. Downstream from the hemB gene, three open-reading frames were found. One of these, transcribed in the same direction as the hemB gene, was identical to be the hemL gene, which encodes glutamate-1-semialdehyde 2,1-aminomutase. The other two open-reading frames, located between the hemYHB and hemL genes, were transcribed divergently, and their deduced amino acid sequences showed similarities to a membrane-bound transport protein and a transcriptional regulatory protein respectively. The two genes may thus be involved in hem transport and the regulation of hem gene expression respectively, and were tentatively named hemX and hemR. Although hemX and hemL are unlikely to be part of the same operon, hemYHBXRL are clustered on the P. freudenreichii chromosome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacillus subtilis / genetics
  • Bacterial Proteins / genetics*
  • Base Sequence
  • Carrier Proteins / genetics
  • Chromosome Mapping
  • DNA, Bacterial / analysis
  • DNA, Bacterial / genetics
  • Escherichia coli / genetics
  • Ferrochelatase / genetics*
  • Genetic Complementation Test
  • Glutamic Acid / metabolism*
  • Heme / metabolism*
  • Intramolecular Transferases*
  • Isomerases
  • Methyltransferases*
  • Molecular Sequence Data
  • Open Reading Frames
  • Operon
  • Oxidoreductases / genetics*
  • Oxidoreductases Acting on CH-CH Group Donors*
  • Plasmids / genetics*
  • Porphobilinogen Synthase / genetics*
  • Propionibacterium / genetics*
  • Propionibacterium / metabolism*
  • Protoporphyrinogen Oxidase
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Transcription, Genetic


  • Bacterial Proteins
  • Carrier Proteins
  • DNA, Bacterial
  • Glutamic Acid
  • Heme
  • Oxidoreductases
  • Oxidoreductases Acting on CH-CH Group Donors
  • Protoporphyrinogen Oxidase
  • Methyltransferases
  • HemX protein, Bacteria
  • Porphobilinogen Synthase
  • Ferrochelatase
  • Isomerases
  • Intramolecular Transferases
  • glutamate-1-semialdehyde 2,1-aminomutase

Associated data

  • GENBANK/D85417