Disease relevance of rapQ

• The pathway and enzymes for tocopherol synthesis are homologous in cyanobacteria and plants except for 2-methyl-6-phytyl-1,4-benzoquinone/2-methyl-6-solanyl-1,4-benzoquinone methyltransferase (MPBQ/MSBQ MT), which catalyzes a key methylation step in both tocopherol and plastoquinone (PQ) synthesis [1].
• Purification and kinetic characterization of the magnesium protoporphyrin IX methyltransferase from Synechocystis PCC6803 [2].
• Thus, active Mg chelatase and Mg-protoporphyrin IX methyltransferase can be coupled in E. coli extracts [3].

High impact information on rapQ

• A gene encoding a methyltransferase (menG) was identified in Synechocystis sp. PCC 6803 as responsible for transferring the methyl group to 2-phytyl-1,4-naphthoquinone in the biosynthetic pathway of phylloquinone, the secondary electron acceptor in photosystem I (PS I) [4].
• A putative 2-methyl-6-phytylbenzoquinone (MPBQ) methyltransferase gene, SLL0418, was identified from the Synechocystis PCC6803 genome based on its homology to previously characterized gamma-tocopherol methyltransferases [5].
• Genetic and biochemical evidence confirmed open reading frame (ORF) SLL0418 encodes a MPBQ methyltransferase [5].
• We propose the designation M.Ssp6803I [corrected] (Synechocystis methyltransferase I) for the slr0214-encoded enzyme [6].
• The complemented R. capsulatus strain contains a defined mutation in the bchM gene that codes for Mg-protoporphyrin IX methyltransferase, the enzyme which converts Mg-protoporphyrin IX to Mg-protoporphyrin IX methylester using S-adenosyl-L-methionine as a cofactor [7].

Biological context of rapQ

• Since chlorophyll biosynthesis also requires the same methylation reaction, the Synechocystis genome should similarly code for a Mg-protoporphyrin IX methyltransferase [7].
• Transient kinetics of the reaction catalysed by magnesium protoporphyrin IX methyltransferase [8].

Anatomical context of rapQ

• The plant S-adenosyl-L-methionine:Mg-protoporphyrin IX methyltransferase is located in both envelope and thylakoid chloroplast membranes [9].

Associations of rapQ with chemical compounds

• Magnesium protoporphyrin IX methyltransferase (ChlM), catalyses the methylation of magnesium protoporphyrin IX (MgP) at the C(6) propionate side chain to form magnesium protoporphyrin IX monomethylester (MgPME) [2].
• The methyltransferase encoded by the gene sll0418 is not essential either for tocopherol or plastoquinone synthesis [10].
• Magnesium protoporphyrin IX methyltransferase (ChlM), an enzyme in the chlorophyll biosynthetic pathway, catalyses the transfer of a methyl group to magnesium protoporphyrin IX (MgP) to form magnesium protoporphyrin IX monomethyl ester (MgPME) [8].

References