The gun4 gene is essential for cyanobacterial porphyrin metabolism.
Ycf53 is a hypothetical chloroplast open reading frame with similarity to the Arabidopsis nuclear gene GUN4. In plants, GUN4 is involved in tetrapyrrole biosynthesis. We demonstrate that one of the two Synechocystis sp. PCC 6803 ycf53 genes with similarity to GUN4 functions in chlorophyll (Chl) biosynthesis as well: cyanobacterial gun4 mutant cells exhibit lower Chl contents, accumulate protoporphyrin IX and show less activity not only of Mg chelatase but also of Fe chelatase. The possible role of Gun4 for the Mg as well as Fe porphyrin biosynthesis branches in Synechocystis sp. PCC 6803 is discussed.
Institut für Biologie, Biochemie der Pflanzen, Humboldt-Universität zu Berlin, Chausseestrasse 117, 10115 Berlin, Germany. annegret.wilde@rz.hu-berlin.de
Annegret
A
Wilde
Sandra
S
Mikolajczyk
Ali
A
Alawady
Heiko
H
Lokstein
Bernhard
B
Grimm
D002736:Chloroplasts / Q000378:metabolism*; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000235:genetics*; D017931:DNA Primers; D005798:Genes, Bacterial / Q000235:genetics*; D007700:Kinetics; D016296:Mutagenesis; D016366:Open Reading Frames; D010641:Phenotype; D011166:Porphyrins / Q000378:metabolism*; D015183:Restriction Mapping
D017931:DNA Primers; D011166:Porphyrins