The Phosphatase RosC from Streptomyces davaonensis is Used for Roseoflavin Biosynthesis and has Evolved to Largely Prevent Dephosphorylation of the Important Cofactor Riboflavin-5'-phosphate.

The antibiotic roseoflavin is a riboflavin (vitamin B) analog. One step of the roseoflavin biosynthetic pathway is catalyzed by the phosphatase RosC, which dephosphorylates 8-demethyl-8-amino-riboflavin-5'-phosphate (AFP) to 8-demethyl-8-amino-riboflavin (AF). RosC also catalyzes the potentially cell-damaging dephosphorylation of the AFP analog riboflavin-5'-phosphate also called "flavin mononucleotide" (FMN), however, with a lower efficiency.

Mutational and structural studies of (βα)-barrel fold methylene-tetrahydropterin reductases utilizing a common catalytic mechanism.

Methylene-tetrahydropterin reductases catalyze the reduction of a methylene to a methyl group bound to a reduced pterin as C carrier in various one-carbon (C) metabolisms. F-dependent methylene-tetrahydromethanopterin (methylene-HMPT) reductase (Mer) and the flavin-independent methylene-tetrahydrofolate (methylene-HF) reductase (Mfr) use a ternary complex mechanism for the direct transfer of a hydride from FH and NAD(P)H to the respective methylene group, whereas FAD-dependent methylene-HF reductase (MTHFR) uses FAD as prosthetic group and a ping-pong mechanism to catalyze the reduction of methylene-HF. A ternary complex structure and a thereof derived catalytic mechanism of MTHFR is available, while no ternary complex structures of Mfr or Mer are reported.

Structural and mechanistic basis of the central energy-converting methyltransferase complex of methanogenesis.

Methanogenic archaea inhabiting anaerobic environments play a crucial role in the global biogeochemical material cycle. The most universal electrogenic reaction of their methane-producing energy metabolism is catalyzed by -methyl-tetrahydromethanopterin: coenzyme M methyltransferase (MtrABCDEFGH), which couples the vectorial Na transport with a methyl transfer between the one-carbon carriers tetrahydromethanopterin and coenzyme M via a vitamin B derivative (cobamide) as prosthetic group. We present the 2.

Crystal structure of FAD-independent methylene-tetrahydrofolate reductase from Mycobacterium hassiacum.

FAD-independent methylene-tetrahydrofolate (methylene-H F) reductase (Mfr), recently identified in mycobacteria, catalyzes the reduction of methylene-H F to methyl-H F with NADH as hydride donor by a ternary complex mechanism. This biochemical reaction corresponds to that of the ubiquitous FAD-dependent methylene-H F reductase (MTHFR), although the latter uses a ping-pong mechanism with the prosthetic group as intermediate hydride carrier. Comparative genomics and genetic analyses indicated that Mfr is indispensable for the growth of Mycobacterium tuberculosis, which lacks the MTHFR encoding gene.

Purification and structural characterization of the Na-translocating ferredoxin: NAD reductase (Rnf) complex of Clostridium tetanomorphum.

Various microbial metabolisms use H/Na-translocating ferredoxin:NAD reductase (Rnf) either to exergonically oxidize reduced ferredoxin by NAD for generating a transmembrane electrochemical potential or reversely to exploit the latter for producing reduced ferredoxin. For cryo-EM structural analysis, we elaborated a quick four-step purification protocol for the Rnf complex from Clostridium tetanomorphum and integrated the homogeneous and active enzyme into a nanodisc. The obtained 4.