A structural model of the membrane-bound aromatic prenyltransferase UbiA from E. coli.
The membrane-bound enzyme 4-hydroxybenzoic acid oligoprenyltransferase (ubiA) from E. coli is crucial for the production of ubiquinone, the essential electron carrier in prokaryotic and eukaryotic organisms. On the basis of previous modeling analyses, amino acids identified as important in two putative active sites (1 and 2) were selectively mutated. All mutants but one lost their ability to form geranylated hydroxybenzoate, irrespective of their being from active site 1 or 2. This suggests either that the two active sites are interrelated or that they are in fact only one site. With the aid of the experimental results and a new structure-based classification of prenylating enzymes, a relevant 3D model could be developed by threading. The new model explains the substrate specificities and is in complete agreement with the results of site-directed mutagenesis. The high similarity of the active fold of UbiA-transferase to that of 5-epi-aristolochene synthase (Nicotiana tabacum), despite a low homology, allows a hypothesis on a convergent evolution of these enzymes to be formed.
Bräuer
Lars
L
Leibniz-Institute of Plant Biochemistry, Department of Bioorganic Chemistry, Weinberg 3, 06120 Halle/Saale, Germany.
Brandt
Wolfgang
W
Schulze
Diana
D
Zakharova
Svetlana
S
Wessjohann
Ludger
L
D000595:Amino Acid Sequence; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism*; D004122:Dimethylallyltranstransferase / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D008565:Membrane Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
D008565:Membrane Proteins; C509554:4-hydroxybenzoic acid oligoprenyltransferase, E coli; D004122:Dimethylallyltranstransferase