Structure of the arginase coding gene and its transcript in Aspergillus nidulans.

Abstract

The arginase structural gene (agaA) from Aspergillus nidulans has been cloned and characterised. Depending on the growth conditions of the mycelium, transcripts of this gene have different 5'ends. These differences could result either from the presence of multiple transcription initiation sites or from differential processing of mRNA. The agaA mRNA has a long 5'UTR with a potentially complex secondary structure. Putative arginine binding aptamers were found in this UTR suggesting interesting possibilities for regulation of the agaA expression.

Rapid Host Defense against Aspergillus fumigatus Involves Alveolar Macrophages with a Predominance of Alternatively Activated Phenotype

“…The fungi C. albicans and Saccharomyces cerevisiae were shown to upregulate expression of genes associated with Arginine biosynthesis in human neutrophils [66] . Taken together, the finding of a role for Arg1 constitutively expressed in human neutrophils in defense against C. albicans [34] , the dependence on L-Arg by fungi as an essential nutrient source [63] , [64] , and our collective data of the role of alveolar macrophages with AAM phenotype in Aspergillus uptake and clearance provide logical explanations for why the host would attempt to rapidly induce Arg1 in the infected lung macrophages. Since Aspergillus is a ubiquitous pathogen and the host has to fight this battle with the fungus continuously, it makes more sense to express Arg1 rather than NOS2 to deplete L-Arg since constant generation of NO via NOS2 activity would be deleterious to lung health.…”

“…However, one important consideration is competition for L-Arg between the germinating fungal spores and the AAMs. The Aspergillus species, A. nidulans , was shown to utilize L-Arg as a source for nitrogen and carbon employing arginase enzymes [63] , [64] . It is likely that Arg1-expressing macrophages competitively deprive the fungus of L-Arg and compromise spore viability.…”

AcpA, a member of the GPR1/FUN34/YaaH membrane protein family, is essential for acetate permease activity in the hyphal fungus Aspergillus nidulans

“…For this gene, one of the several different transcription products that result from multiple initiation transcription sites was shown to modulate the degradation of all JEN1-specific mRNAs [40]. Another gene with an intron in its 5'UTR is the arginase encoding gene agaA of A. nidulans [41]. This intron leads to the generation of various mRNA isoforms that influence not only mRNA stability but also their activities as templates for translation by a riboswitch mechanism [42].…”

MIPs and Aptamers for Recognition of Proteins in Biomimetic Sensing

“…The best known riboswitches are found in bacteria [ 130 ], and also in plant and fungi [ 131 ]. The existence of natural regulatory aptamers (riboswitches) was discovered by the observations of homologies between RNA sequences in the 5′-untranslated region of transcripts and in vitro selected RNA aptamers [ 132 ]. The binding of the metabolite by an aptamer sequence induces a modulation of the ribosomal binding site (RBS) by a structural change of the proximal expression platform, which regulates the specific gene expression.…”