Structure of coenzyme F(420) dependent methylenetetrahydromethanopterin reductase from two methanogenic archaea.
Coenzyme F(420)-dependent methylenetetrahydromethanopterin reductase (Mer) is an enzyme of the Cl metabolism in methanogenic and sulfate reducing archaea. It is composed of identical 35-40 kDa subunits and lacks a prosthetic group. The crystal structure of Mer from Methanopyrus kandleri (kMer) revealed in one crystal form a dimeric and in another a tetrameric oligomerisation state and that from Methanobacterium thermoautotrophicum (tMer) a dimeric state. Each monomer is primarily composed of a TIM-barrel fold enlarged by three insertion regions. Insertion regions 1 and 2 contribute to intersubunit interactions. Insertion regions 2 and 3 together with the C-terminal end of the TIM-barrel core form a cleft where the binding sites of coenzyme F(420) and methylene-tetrahydromethanopterin are postulated. Close to the coenzyme F(420)-binding site lies a rarely observed non-prolyl cis-peptide bond. It is surprising that Mer is structurally most similar to a bacterial FMN-dependent luciferase which contains a non-prolyl cis-peptide bond at the equivalent position. The structure of Mer is also related to that of NADP-dependent FAD-harbouring methylenetetrahydrofolate reductase (MetF). However, Mer and MetF do not show sequence similarities although they bind related substrates and catalyze an analogous reaction.
Shima
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S
Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch Strasse, Marburg, 35043, Germany.
Warkentin
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E
Grabarse
W
W
Sordel
M
M
Wicke
M
M
Thauer
R K
RK
Ermler
U
U
D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D004777:Environment; D019605:Euryarchaeota / Q000201:enzymology*; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry / Q000378:metabolism; D005415:Flavins / Q000737:chemistry / Q000378:metabolism; D017014:Methanobacterium / Q000201:enzymology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000737:chemistry* / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D012256:Riboflavin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D016415:Sequence Alignment
D005415:Flavins; D005182:Flavin-Adenine Dinucleotide; C015084:coenzyme F420; D000587:Oxidoreductases Acting on CH-NH Group Donors; C047126:methylenetetrahydromethanopterin dehydrogenase; D012256:Riboflavin