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Nitric oxide synthesis by nitrate reductase is regulated during development in A spergillus
Author(s) -
Marcos Ana T.,
Ramos María S.,
Marcos Jose F.,
Carmona Lourdes,
Strauss Joseph,
Cánovas David
Publication year - 2016
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.13211
Subject(s) - conidiation , biology , nitrate reductase , aspergillus nidulans , psychological repression , nitric oxide , downregulation and upregulation , microbiology and biotechnology , biochemistry , gene expression , mutant , gene , enzyme , endocrinology
Summary Nitric oxide ( NO ) is a signalling molecule involved in many biological processes in bacteria, plants and mammals. However, little is known about the role and biosynthesis of NO in fungi. Here we show that NO production is increased at the early stages of the transition from vegetative growth to development in A spergillus nidulans . Full NO production requires a functional nitrate reductase ( NR ) gene ( nia D ) that is upregulated upon induction of conidiation, even under N ‐repressing conditions in the presence of ammonium. At this stage, NO homeostasis is achieved by balancing biosynthesis ( NR ) and catabolism (flavohaemoglobins). nia D and flavohaemoglobin fhb A are transiently upregulated upon induction of conidiation, and both regulators AreA and NirA are necessary for this transcriptional response. The second flavohaemoglobin gene fhb B shows a different expression profile being moderately expressed during the early stages of the transition phase from vegetative growth to conidiation, but it is strongly induced 24 h later. NO levels influence the balance between conidiation and sexual reproduction because artificial strong elevation of NO levels reduced conidiation and induced the formation of cleistothecia. The nitrate‐independent and nitrogen metabolite repression‐insensitive transcriptional upregulation of nia D during conidiation suggests a novel role for NR in linking metabolism and development.