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GlxA is a new structural member of the radical copper oxidase family and is required for glycan deposition at hyphal tips and morphogenesis of Streptomyces lividans

DOI: 10.1042/BJ20150190 DOI Help
PMID: 26205496 PMID Help

Authors: Amanda Chaplin (University of Essex) , Marloes Petrus (Leiden University) , Giulia Mangiameli (Leiden University) , Mike Hough (University of Essex) , Dimitri Svistunenko (University of Essex) , Peter Nicholls (University of Essex) , Dennis Claessen (Leiden University) , Eric Vijgenboom (Leiden University) , Jonathan Worrall (University of Essex)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Biochemical Journal

State: Published (Approved)
Published: June 2015
Diamond Proposal Number(s): 7461

Abstract: Streptomyces lividans displays a distinct dependence on copper to fully initiate morphological development. Evidence has accumulated to implicate the participation of an extracytoplasmic cuproenzyme in morphogenesis. Here we show that GlxA fulfils all criteria to be that cuproenzyme. GlxA is membrane associated and has an active site consisting of a mononuclear copper and a cross-linked Tyr-Cys co-factor. The domain organisation of the tertiary structure defines GlxA as a new structural member of the mono-copper oxidase family, with copper coordination geometry similar to, but spectroscopically distinct from fungal galactose oxidase. Electron paramagnetic resonance spectroscopy reveals that the oxidation of cupric GlxA generates a protein radical residing on the Tyr-Cys cross-link. A variety of canonical galactose oxidase substrates (including D-galactose) were tested but none were readily turned over by GlxA. A glxA null-mutant leads to loss of glycan accumulation at hyphal tips and consequently a drastically changed morphology both on solid substrates and in liquid-grown environments, a scenario similarly observed in the absence of the neighbouring glycan synthase CslA. In addition the glxA mutant has lost the stimulation of development by copper, supporting a model whereby the enzymatic action of GlxA on the glycan is required for development and morphology. From a biotechnology perspective the open mycelium morphology observed with the glxA mutant in submerged culture has implications for use as an enzyme production host.

Subject Areas: Biology and Bio-materials


Instruments: I03-Macromolecular Crystallography

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