Magnesium-protoporphyrin chelatase of Rhodobacter sphaeroides

reconstitution of activity by combining the products of the bchH, -I, and -D genes expressed in Escherichia coli

Lucien C D Gibson*, Robert D. Willows, C. Gamini Kannangara, Diter Von Wettstein, C. Neil Hunter

*Corresponding author for this work

Research output: Contribution to journalArticle

147 Citations (Scopus)

Abstract

Magnesium-protoporphyrin chelatase lies at the branch point of the heme and (bacterio)chlorophyll biosynthetic pathways. In this work, the photosynthetic bacterium Rhodobacter sphaeroides has been used as a model system for the study of this reaction. The bchH and the bchI and -D genes from R. sphaeroides were expressed in Escherichia coli. When cell-free extracts from strains expressing BchH, BchI, and BchD were combined, the mixture was able to catalyze the insertion of Mg into protoporphyrin IX in an ATP-dependent manner. This was possible only when all three genes were expressed. The bchH, -I, and -D gene products are therefore assigned to the Mg chelatase step in bacteriochlorophyll biosynthesis. The mechanism of the Mg chelation reaction and the implications for chlorophyll biosynthesis in plants are discussed.

Original languageEnglish
Pages (from-to)1941-1944
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume92
Issue number6
DOIs
Publication statusPublished - 14 Mar 1995
Externally publishedYes

Keywords

  • bacteriochlorophyll
  • chlorophyll
  • photosynthesis
  • protoporphyrin IX
  • tetrapyrrole

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