Structural Biology Studies On FrB Series Phosphonate Synthase And Carboline Skeleton Synthase McbB

FR900098 is a natural fosmidomycin antibiotics. In most pathogens, such as Plasmodium falciparum, Streptococcus pneumoniae, Salmonella, Typhoid bacteria and E. coli, isoprenoid are synthesized via a non-mevalonate pathway, the so-called 2-C-methyl-D-erythritol-4-phosphate(MEP)pathway,which is absent in mammals, including humans. The FR900098 is a strong inhibitor of the DXR, the second enzyme in the MEP pathway, but does not affect our isoprenoid synthesis. Which make the FR900098 an effective antimalarial. The FR900098 biosynthesis in microorganisms remains poorly understood. So, in order to reveal the catalytic mechanism of FR900098 biosynthesis synthase,we obtained the crystals of FR900098 synthase(FrbB and FrbD). And we used the X-ray single crystal diffraction methods to resolve FrbB, FrbD protein structure. The studies on the structural of FrbB and FrbD enzyme, which will reveal the catalytic mechanisms to catalytic reaction and provide the structural basis for the FR900098 biosynthetic pathway.FrbJ is a member of the Fe(Ⅱ) ?α-ketoglutarate-dependent dioxygenases family, which hydroxylates the natural product FR-900098 yielding phosphonate antibiotic FR-33289. It also catalyzes the hydroxylation reactions with other substrates including fosmidomycin, methyl-fosmidomycin, and methyl-FR-900098. The products of these reactions were used to construct a library of potential antimalarial compounds. Here we report the crystal structure of FrbJ, which shows structural homology to taurine catabolism dioxygenase TauD, a key member of the same family. Unlike other members in the family, FrbJ has an unusual lid structure. To investigate the role of this lid motif, molecular dynamics simulation was performed with the FrbJ structure. The molecular dynamics simulation analysis implies that the lid loop region is highly flexible, which is consistent with the fact that FrbJ has a relatively broad spectrum of substrates with different lengths. Interestingly, an access tunnel is found in the back of the active site, which connects the putative binding site of α-ketoglutarate to the solvent outside. The studies on the structural of FrbJ enzyme, which will reveal the catalytic mechanisms to catalytic reaction.β-carboline alkaloids as an important compound that are widely distributed in plants, bacteria, fungi and marine microorganisms. β-carboline alkaloids have exhibit important pharmacological,such as antiallergic, antiviral, anti-inflammatory, antibacterial and with activities against Plasmodium falciparum. McbB can catalyze the Pictet-Spengler(PS) reaction of L-tryptophan and oxaloacetaldehyde to produce the β-carboline alkaloids. McbB also can involves decarboxylation and oxidation reactions. In this study, we have obtained McbB crystal and resolved McbB three-dimensional structure. The structural analysis show that Glu97 in McbB is vital for its activities. The studies on the structural of McbB, which will help to reveal the catalytic mechanism of Mcb B and provide important the basis for the enzyme engineering by rational design.