Rubrivivax gelatinosus acsF (Previously orf358) Codes for a Conserved, Putative Binuclear-Iron-Cluster-Containing Protein Involved in Aerobic Oxidative Cyclization of Mg-Protoporphyrin IX Monomethylester
AUTOR(ES)
Pinta, Violaine
FONTE
American Society for Microbiology
RESUMO
This study describes the characterization of orf358, an open reading frame of previously unidentified function, in the purple bacterium Rubrivivax gelatinosus. A strain in which orf358 was disrupted exhibited a phenotype similar to the wild type under photosynthesis or low-aeration respiratory growth conditions. In contrast, under highly aerated respiratory growth conditions, the wild type still produced bacteriochlorophyll a (Bchl a), while the disrupted strain accumulated a compound that had the same absorption and fluorescence emission spectra as Mg-protoporphyrin but was less polar, suggesting that it was Mg-protoporphyrin monomethylester (MgPMe). These data indicated a blockage in Bchl a synthesis at the oxidative cyclization stage and implied the coexistence of two different mechanisms for MgPMe cyclization in R. gelatinosus, an anaerobic mechanism active under photosynthesis or low oxygenation and an aerobic mechanism active under high-oxygenation growth conditions. Based on these results as well as on sequence analysis indicating the presence of conserved putative binuclear-iron-cluster binding motifs, the designation of orf358 as acsF (for aerobic cyclization system Fe-containing subunit) is proposed. Several homologs of AcsF were found in a wide range of photosynthetic organisms, including Chlamydonomas reinhardtii Crd1 and Pharbitis nil PNZIP, suggesting that this aerobic oxidative cyclization mechanism is conserved from bacteria to plants.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=139524Documentos Relacionados
- Separation of Mg-Protoporphyrin IX and Mg-Protoporphyrin IX Monomethyl Ester Synthesized de novo by Developing Cucumber Etioplasts 1
- Xantha-l encodes a membrane subunit of the aerobic Mg-protoporphyrin IX monomethyl ester cyclase involved in chlorophyll biosynthesis
- The Chlorophyll Biosynthetic Enzyme Mg-Protoporphyrin IX Monomethyl Ester (Oxidative) Cyclase (Characterization and Partial Purification from Chlamydomonas reinhardtii and Synechocystis sp. PCC 6803).
- Topological Model of the Rhodobacter capsulatus Light-Harvesting Complex I Assembly Protein LhaA (Previously Known as ORF1696)
- Accumulation of protoporphyrin IX and Zn protoporphyrin IX in Cyanidium caldarium