The heme oxygenase gene (pbsA) in the red alga Rhodella violacea is discontinuous and transcriptionally activated during iron limitation

Proc Natl Acad Sci U S A. 1997 Oct 14;94(21):11736-41. doi: 10.1073/pnas.94.21.11736.


Heme oxygenase (HO) catalyzes the opening of the heme ring with the release of iron in both plants and animals. In cyanobacteria, red algae, and cryptophyceae, HO is a key enzyme in the synthesis of the chromophoric part of the photosynthetic antennae. In an attempt to study the regulation of this key metabolic step, we cloned and sequenced the pbsA gene encoding this enzyme from the red alga Rhodella violacea. The gene is located on the chloroplast genome, split into three distant exons, and is presumably expressed by a trans-splicing mechanism. The deduced polypeptide sequence is homologous to other reported HOs from organisms containing phycobilisomes (Porphyra purpurea and Synechocystis sp. strain PCC 6803) and, to a lesser extent, to vertebrate enzymes. The expression is transcriptionally activated under iron deprivation, a stress condition frequently encountered by algae, suggesting a second role for HO as an iron-mobilizing agent in photosynthetic organisms.

Publication types

  • Comparative Study

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Chickens
  • Chloroplasts / enzymology
  • Cyanobacteria / genetics
  • DNA Primers
  • Exons
  • Gene Expression Regulation, Enzymologic*
  • Genes, Plant
  • Genomic Library
  • Heme Oxygenase (Decyclizing) / biosynthesis*
  • Heme Oxygenase (Decyclizing) / chemistry
  • Heme Oxygenase (Decyclizing) / genetics
  • Humans
  • Iron / metabolism*
  • Iron / pharmacology
  • Molecular Sequence Data
  • Phycobilisomes
  • Polymerase Chain Reaction
  • Restriction Mapping
  • Rhodophyta / drug effects
  • Rhodophyta / enzymology*
  • Rhodophyta / genetics*
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Transcription, Genetic*


  • DNA Primers
  • Phycobilisomes
  • Iron
  • Heme Oxygenase (Decyclizing)

Associated data

  • GENBANK/AF000717
  • GENBANK/AF000718
  • GENBANK/AF000719