title: Crystal structure of methylenetetrahydromethanopterin reductase (Mer) in complex with coenzyme F420: Architecture of the F420/FMN binding site of enzymes within the nonprolyl cis-peptide containing bacterial luciferase family.
abstract: Methylenetetratetrahydromethanopterin reductase (Mer) is involved in CO(2) reduction to methane in methanogenic archaea and catalyses the reversible reduction of methylenetetrahydromethanopterin (methylene-H(4)MPT) to methyl-H(4)MPT with coenzyme F(420)H(2), which is a reduced 5'-deazaflavin. Mer was recently established as a TIM barrel structure containing a nonprolyl cis-peptide bond but the binding site of the substrates remained elusive. We report here on the crystal structure of Mer in complex with F(420) at 2.6 A resolution. The isoalloxazine ring is present in a pronounced butterfly conformation, being induced from the Re-face of F(420) by a bulge that contains the non-prolyl cis-peptide bond. The bindingmode of F(420) is very similar to that in F(420)-dependent alcohol dehydrogenase Adf despite the low sequence identity of 21%. Moreover, binding of F(420) to the apoenzyme was only associated with minor conformational changes of the polypeptide chain. These findings allowed us to build an improved model of FMN into its binding site in bacterial luciferase, which belongs to the same structural family as Mer and Adf and also contains a nonprolyl cis-peptide bond in an equivalent position.
authors.affiliation: Max-Planck-Institut für terrestrische Mikrobiologie, Marburg, Germany.
authors.forename: Stephan W
authors.initials: SW
authors.lastname: Aufhammer
authors.forename: Eberhard
authors.initials: E
authors.lastname: Warkentin
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ermler
authors.forename: Christoph H
authors.initials: CH
authors.lastname: Hagemeier
authors.forename: Rudolf K
authors.initials: RK
authors.lastname: Thauer
authors.forename: Seigo
authors.initials: S
authors.lastname: Shima
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D005486:Flavin Mononucleotide / Q000737:chemistry / Q000378:metabolism; D005415:Flavins; D008156:Luciferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017014:Methanobacterium / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011392:Proline / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D012256:Riboflavin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D005415:Flavins; D010455:Peptides; C008173:isoalloxazine; C015084:coenzyme F420; D005486:Flavin Mononucleotide; D011392:Proline; D000429:Alcohol Oxidoreductases; D008156:Luciferases; C071832:alkanol monooxygenase (FMN-linked); D000587:Oxidoreductases Acting on CH-NH Group Donors; C047126:methylenetetrahydromethanopterin dehydrogenase; D012256:Riboflavin