Disease relevance of APG1

• In vitro enzyme assays confirmed that VTE3 is the plant functional equivalent of the previously characterized MPBQ/MSBQ MT (Sll0418) from Synechocystis sp PCC6803, although the two proteins are highly divergent in primary sequence [1].
• In vivo analyses of vte3 mutants and the corresponding homozygous Synechocystis sp PCC6803 sll0418::aphII mutant revealed important differences in enzyme redundancy, the regulation of tocopherol synthesis, and the integration of tocopherol and PQ biosynthesis in cyanobacteria and plants [1].

High impact information on APG1

• VTE3 orthologs are present in all vascular and nonvascular plant databases and in C. reinhardtii but absent from cyanobacterial genomes [1].
• The phenotypes of vte3 mutants are consistent with the disruption of MPBQ/MSBQ MT activity to varying extents [1].
• Molecular dissection of the pathway in plants is now complete with the cloning and characterization of the gene for Arabidopsis MPBQ/MSBQ methyltransferase (VITAMIN E 3; VTE3) [2].
• The apg1 plants lacked plastoquinone (PQ), suggesting that the APG1 protein is involved in the methylation step of PQ biosynthesis, which is localized at the envelope membrane [3].

Associations of APG1 with chemical compounds

• Intriguingly, the only prokaryotic genomes that contain VTE3-like sequences are those of two species of archea, suggesting that, in contrast to all other enzymes of the plant tocopherol pathway, the evolutionary origin of VTE3 may have been archeal rather than cyanobacterial [1].

References