Nejvíce citovaný článek - PubMed ID 28699733
Diversity of Alkylproline Moieties in Pyrrolobenzodiazepines Arises from Postcondensation Modifications of a Unified Building Block
- MeSH
- anthramycin chemie MeSH
- bakteriální proteiny chemie MeSH
- katalytická doména MeSH
- kyseliny fenylpyrohroznové chemie MeSH
- linkomycin chemie MeSH
- metylace MeSH
- molekulární struktura MeSH
- mutace MeSH
- prolin chemie MeSH
- Streptomyces chemie MeSH
- uhlík chemie MeSH
- vazba proteinů MeSH
- Publikační typ
- dopisy MeSH
- práce podpořená grantem MeSH
- Názvy látek
- anthramycin MeSH
- bakteriální proteiny MeSH
- kyseliny fenylpyrohroznové MeSH
- linkomycin MeSH
- phenylpyruvic acid MeSH Prohlížeč
- prolin MeSH
- uhlík MeSH
Natural pyrrolobenzodiazepines (PBDs) form a large and structurally diverse group of antitumour microbial metabolites produced through complex pathways, which are encoded within biosynthetic gene clusters. We sequenced the gene cluster of limazepines and proposed their biosynthetic pathway based on comparison with five available gene clusters for the biosynthesis of other PBDs. Furthermore, we tested two recombinant proteins from limazepine biosynthesis, Lim5 and Lim6, with the expected substrates in vitro. The reactions monitored by LC-MS revealed that limazepine biosynthesis involves a new way of 3-hydroxyanthranilic acid formation, which we refer to as the chorismate/DHHA pathway and which represents an alternative to the kynurenine pathway employed for the formation of the same precursor in the biosynthesis of other PBDs. The chorismate/DHHA pathway is presumably also involved in the biosynthesis of PBD tilivalline, several natural products unrelated to PBDs, and its part is shared also with phenazine biosynthesis. The similarities between limazepine and phenazine biosynthesis indicate tight evolutionary links between these groups of compounds.
- MeSH
- benzodiazepiny chemie metabolismus MeSH
- chromatografie kapalinová MeSH
- hmotnostní spektrometrie MeSH
- kyselina 3-hydroxyanthranilová metabolismus MeSH
- metabolické sítě a dráhy MeSH
- molekulární evoluce MeSH
- sekvenční analýza proteinů MeSH
- Streptomyces genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- benzodiazepiny MeSH
- kyselina 3-hydroxyanthranilová MeSH
Adenylation domains CcbC and LmbC control the specific incorporation of amino acid precursors in the biosynthesis of lincosamide antibiotics celesticetin and lincomycin. Both proteins originate from a common L-proline-specific ancestor, but LmbC was evolutionary adapted to use an unusual substrate, (2S,4R)-4-propyl-proline (PPL). Using site-directed mutagenesis of the LmbC substrate binding pocket and an ATP-[32P]PPi exchange assay, three residues, G308, A207 and L246, were identified as crucial for the PPL activation, presumably forming together a channel of a proper size, shape and hydrophobicity to accommodate the propyl side chain of PPL. Subsequently, we experimentally simulated the molecular evolution leading from L-proline-specific substrate binding pocket to the PPL-specific LmbC. The mere change of three amino acid residues in originally strictly L-proline-specific CcbC switched its substrate specificity to prefer PPL and even synthetic alkyl-L-proline derivatives with prolonged side chain. This is the first time that such a comparative study provided an evidence of the evolutionary relevant adaptation of the adenylation domain substrate binding pocket to a new sterically different substrate by a few point mutations. The herein experimentally simulated rearrangement of the substrate binding pocket seems to be the general principle of the de novo genesis of adenylation domains' unusual substrate specificities. However, to keep the overall natural catalytic efficiency of the enzyme, a more comprehensive rearrangement of the whole protein would probably be employed within natural evolution process.
