EcdGHK are Three Tailoring Iron Oxygenases for Amino Acid Building Blocks of the Echinocandin Scaffold

Details

• Alternative Title:
  J Am Chem Soc
• Personal Author:
  Jiang, Wei ; Cacho, Ralph A ; Chiou, Grace ; Garg, Neil K ; Tang, Yi ; Walsh, Christopher T
• Description:
  The echinocandins are a small group of fungal N-acylated cyclic hexapeptides that are fungicidal for candida strains and fungistatic for aspergilli by targeting cell wall 1,3-β-glucan synthases. The side chains of all six amino acid building blocks have hydroxyl groups, including the nonproteinogenic 4R,5R-dihydroxy-Orn1, 4R-OH-Pro3, 3S,4S-dihydroxy-homoTyr4, and 3S-OH-4S-Me-Pro6. The echinocandin (ecd) gene cluster contains two predicted nonheme mononuclear iron oxygenase genes (ecdG,K) and one encoding a P450 type heme protein (ecdH). Deletion of the ecdH gene in the producing strain Emericella rugulosa generates an echinocandin scaffold (echinocandin D) lacking both hydroxyl groups on Orn1. Correspondingly, the ΔecdG strain failed to hydroxylate C3 of the homoTyr residue, and purified EcdG hydroxylated free L-homoTyr at C3. The ΔecdK strain failed to generate mature echinocandin unless supplemented with either 4R-Me-Pro or 3S-OH-4S-Me-Pro, indicating blockage of a step upstream of Me-Pro formation. Purified EcdK is a Leu 5-hydroxylase, acting iteratively at C5 to yield γ-Me-Glu-γ-semialdehyde in equilibrium with the cyclic imine product. Evaluation of deshydroxyechinocandin scaffolds in the in vitro anticandidal assays revealed up to a 3-fold loss of potency for the ΔecdG scaffolds, but a 3-fold gain of potency for the ΔecdH scaffold, in line with prior results on deoxyechinocandin homologues.
• Keywords:
  Antifungal Agents Candida Candidiasis Echinocandins Emericella Gene Deletion Humans Iron Multigene Family Oxygenases
• Source:
  J Am Chem Soc. 135(11):4457-4466
• Pubmed ID:
  23451921
• Pubmed Central ID:
  PMC3628723
• Document Type:
  Journal Article
• Funding:
  R01 GM092217/GM/NIGMS NIH HHSUnited States/ ; DP1 GM106413/GM/NIGMS NIH HHSUnited States/ ; 1R01GM092217/GM/NIGMS NIH HHSUnited States/ ; 1R01GM49338/GM/NIGMS NIH HHSUnited States/ ; T32 GM008496/GM/NIGMS NIH HHSUnited States/ ; 1DP1GM106413/DP/NCCDPHP CDC HHSUnited States/ ; R01 GM049338/GM/NIGMS NIH HHSUnited States/ ; GM08496/GM/NIGMS NIH HHSUnited States/
• Volume:
  135
• Issue:
  11
• Collection(s):
  CDC Public Access
• Main Document Checksum:
  urn:sha256:7e4947cb1edd0afb0adfc20094db5a8ae18460245513b26904928f0bc0f6cc14
• Download URL:
  https://stacks.cdc.gov/view/cdc/29645/cdc_29645_DS1.pdf
• File Type:
  [PDF - 979.08 KB ]