6c5b
From Proteopedia
Crystal Structure Analysis of LaPhzM
Structural highlights
FunctionPHZM_LYSAN Involved in the biosynthesis of phenazine natural products including myxin, an N(5),N(10)-dioxide phenazine antiobiotic, which has antimicrobial activity. O-methyltransferase, which converts iodinin (1,6-dihydroxyphenazine N(5),N(10)-dioxide) to myxin (1-hydroxy-6-methoxyphenazine N(5),N(10)-dioxide). Catalyzes both monomethoxy and dimethoxy formation of phenazine natural compounds. Acts on a wide variety of substrates, catalyzing O-methylation of phenazines with non-, mono- or di-N-oxide. Highest activity with 1,6-dihydroxyphenazine (DHP) as substrate. Less active with monohydroxy-containing and monohydroxy-monomethoxy-containing phenazines. Least active with non-phenazine substrates, such as 8-hydroxyquinoline and 6-hydroxyquinoline. Is not able to convert 1-hydroxyphenazine to 1-hydroxy-N5-methylphenazine (pyocyanine), hence does not function as an N-methyltransferase.[1] Publication Abstract from PubMedMyxin is a well-known antibiotic that had been used for decades. It belongs to the phenazine natural products that exhibit various biological activities, which are often dictated by the decorating groups on the heteroaromatic three-ring system. The three rings of myxin carry a number of decorations, including an unusual aromatic N5, N10-dioxide. We previously showed that phenazine 1,6-dicarboxylic acid (PDC) is the direct precursor of myxin, and two redox enzymes (LaPhzS and LaPhzNO1) catalyze the decarboxylative hydroxylation and aromatic N-oxidations of PDC to produce iodinin (1.6-dihydroxy- N5, N10-dioxide phenazine). In this work, we identified the LaPhzM gene from Lysobacter antibioticus OH13 and demonstrated that LaPhzM encodes a SAM-dependent O-methyltransferase converting iodinin to myxin. The results further showed that LaPhzM is responsible for both monomethoxy and dimethoxy formation in all phenazine compounds isolated from strain OH13. LaPhzM exhibits relaxed substrate selectivity, catalyzing O-methylation of phenazines with non-, mono-, or di- N-oxide. In addition, we demonstrated a one-pot biosynthesis of myxin by in vitro reconstitution of the three phenazine-ring decorating enzymes. Finally, we determined the X-ray crystal structure of LaPhzM with a bound cofactor at 1.4 A resolution. The structure provided molecular insights into the activity and selectivity of the first characterized phenazine O-methyltransferase. These results will facilitate future exploitation of the thousands of phenazines as new antibiotics through metabolic engineering and chemoenzymatic syntheses. Functional and Structural Analysis of Phenazine O-Methyltransferase LaPhzM from Lysobacter antibioticus OH13 and One-Pot Enzymatic Synthesis of the Antibiotic Myxin.,Jiang J, Guiza Beltran D, Schacht A, Wright S, Zhang L, Du L ACS Chem Biol. 2018 Mar 12. doi: 10.1021/acschembio.8b00062. PMID:29510028[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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