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oai:riubu.ubu.es:10259/49602024-07-24T11:41:14Zcom_10259_9476com_10259.4_106com_10259_2604col_10259_9477

2018-10-08T09:17:18Z urn:hdl:10259/4960 Forward genetics by genome sequencing uncovers the central role of the aspergillus niger goxB locus in hydrogen peroxide induced glucose oxidase expression Laothanachareon, Thanaporm Tamayo Ramos, Juan Antonio Nijsse, Bart Schaap, Peter J. forward genetics genome sequencing Aspergillus niger N402 goxB glucose oxidase Aspergillus niger is an industrially important source for gluconic acid and glucose oxidase (GOx), a secreted commercially important flavoprotein which catalyses the oxidation of b-D-glucose by molecular oxygen to D-glucolactone and hydrogen peroxide. Expression of goxC, the GOx encoding gene and the concomitant two step conversion of glucose to gluconic acid requires oxygen and the presence of significant amounts of glucose in the medium and is optimally induced at pH 5.5. The molecular mechanisms underlying regulation of goxC expression are, however, still enigmatic. Genetic studies aimed at understanding GOx induction have indicated the involvement of at least seven complementation groups, for none of which the molecular basis has been resolved. In this study, a mapping-by-sequencing forward genetics approach was used to uncover the molecular role of the goxB locus in goxC expression. Using the Illumina and PacBio sequencing platforms a hybrid high quality draft genome assembly of laboratory strain N402 was obtained and used as a reference for mapping of genomic reads obtained from the derivative NW103:goxB mutant strain. The goxB locus encodes a thioredoxin reductase. A deletion of the encoding gene in the N402 parent strain led to a high constitutive expression level of the GOx and the lactonase encoding genes required for the two-step conversion of glucose in gluconic acid and of the catR gene encoding catalase R. This high constitutive level of expression was observed to be irrespective of the carbon source and oxidative stress applied. A model clarifying the role of GoxB in the regulation of the expression of goxC involving hydrogen peroxide as second messenger is presented. 2018-10-08T09:17:18Z 2018-10-08T09:17:18Z 2018-09 info:eu-repo/semantics/article 1664-302X http://hdl.handle.net/10259/4960 10.3389/fmicb.2018.02269 eng Frontiers in Microbiology. 2018, V. 9, art. 2269 https://doi.org/10.3389/fmicb.2018.02269 http://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess Attribution 4.0 International Frontiers Media