Activities | Families | Sequences | Fold types | References | Help
B6db references: 16339726

type Journal Article
authors Atteia A, van Lis R, Beale SI.
title Enzymes of the heme biosynthetic pathway in the nonphotosynthetic alga Polytomella sp.
journal Eukaryot Cell
sel selected
ui 16339726
year (2005)
volume 4
number 12
pages 2087-97
keywords Aldehyde Oxidoreductases/*drug effects
abstract Heme biosynthesis involves a number of enzymatic steps which in eukaryotes take place in different cell compartments. Enzyme compartmentalization differs between photosynthetic and nonphotosynthetic eukaryotes. Here we investigated the structures and subcellular localizations of three enzymes involved in the heme pathway in Polytomella sp., a colorless alga evolutionarily related to the green alga Chlamydomonas reinhardtii. Functional complementation of Escherichia coli mutant strains was used to isolate cDNAs encoding three heme biosynthetic enzymes, glutamate-1-semialdehyde aminotransferase, protoporphyrinogen IX oxidase, and ferrochelatase. All three proteins show highest similarity to their counterparts in photosynthetic organisms, including C. reinhardtii. All three proteins have N-terminal extensions suggestive of intracellular targeting, and immunoblot studies indicate their enrichment in a dense cell fraction that is enriched in amyloplasts. These results suggest that even though the plastids of Polytomella sp. are not photosynthetically active, they are the major site of heme biosynthesis. The presence of a gene for glutamate-1-semialdehyde aminotransferase suggests that Polytomella sp. uses the five-carbon pathway for synthesis of the heme precursor 5-aminolevulinic acid.
last changed 2008/05/21 16:30

B6db references