title: Molecular machines encoded by bacterially-derived multi-domain gene fusions that potentially synthesize, N-methylate and transfer long chain polyamines in diatoms.
abstract: Silica glass formation in diatoms requires the biosynthesis of unusual, very long chain polyamines (LCPA) composed of iterated aminopropyl units. Diatoms processively synthesize LCPA, N-methylate the amine groups and transfer concatenated, N-dimethylated aminopropyl groups to silaffin proteins. Here I show that diatom genomes possess signal peptide-containing gene fusions of bacterially-derived polyamine biosynthetic enzymes S-adenosylmethionine decarboxylase (AdoMetDC) and an aminopropyltransferase, sometimes fused to a eukaryotic histone N-methyltransferase domain, that potentially synthesize and N-methylate LCPA. Fusions of similar, alternatively configured domains but with a catalytically dead AdoMetDC and in one case a Tudor domain, may N-dimethylate and transfer multiple aminopropyl unit polyamines onto silaffin proteins.
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9041, USA. anthony.michael@utsouthwestern.edu
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Michael
mesh_terms: D012437:Adenosylmethionine Decarboxylase / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000145:classification / Q000235:genetics; D017377:Diatoms / Q000201:enzymology* / Q000378:metabolism*; D050939:Gene Fusion / Q000235:genetics / Q000502:physiology*; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D011073:Polyamines / Q000737:chemistry / Q000378:metabolism*; D011436:Spermidine Synthase / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D011073:Polyamines; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase; D011436:Spermidine Synthase; D012437:Adenosylmethionine Decarboxylase