The gene cutA of Fusarium fujikuroi, encoding a protein of the haloacid dehalogenase family, is involved in osmotic stress and glycerol metabolism

Abstract

Survival of micro-organisms in natural habitats depends on their ability to adapt to variations in osmotic conditions. We previously described the gene cut-1 of Neurospora crassa, encoding a protein of the haloacid dehalogenase family with an unknown function in the osmotic stress response. Here we report on the functional analysis of cutA, the orthologous gene in the phytopathogenic fungus Fusarium fujikuroi. cutA mRNA levels increased transiently after exposure to 0.68 M NaCl and were reduced upon return to normal osmotic conditions; deletion of the gene resulted in a partial reduction in tolerance to osmotic stress. ΔcutA mutants contained much lower intracellular levels of glycerol than the wild-type, and did not exhibit the increase following hyper-osmotic shock expected from the high osmolarity glycerol (HOG) response. cutA is linked and divergently transcribed with the putative glycerol dehydrogenase gene gldB, which showed the same regulation by osmotic shock. The intergenic cutA/gldB regulatory region contains putative stress-response elements conserved in other fungi, and both genes shared other regulatory features, such as induction by heat shock and by illumination. Photoinduction was also observed in the HOG response gene hogA, and was lost in mutants of the white collar gene wcoA. Previous data on glycerol production in Aspergillus spp. and features of the predicted CutA protein lead us to propose that F. fujikuroi produces glycerol from dihydroxyacetone, and that CutA is the enzyme involved in the synthesis of this precursor by dephosphorylation of dihydroxyacetone-3P.

Back to the Salt Mines: Genome and Transcriptome Comparisons of the Halophilic Fungus Aspergillus salisburgensis and Its Halotolerant Relative Aspergillus sclerotialis

“…This is similar to the use of chlorine for wood pulp delignification [90]. In the fungi Fusarium fujikuroi and Neurospora crassa , genes belonging to the haloacid dehalogenase family were shown to be involved in the osmotic stress and glycerol metabolism [91]. Conserved genes downregulated in both species are related to amino acid transport, trehalose-phosphatase, thiolase, and the p53 transcription factor.…”

Interspecies DNA acquisition by a naturally competentAcinetobacter baumanniistrain

“…Additionally, we identified the cutA gene that encodes for a dihydroorotate dehydrogenase, which has an enzymatic function associated with copper tolerance and osmotic stress (31, 32), but also related to plasmid and chromosomal replication (31, 33). This can explain the potential of cutA to be transferred between different bacterial species.…”

Interspecies DNA acquisition by a naturally competent Acinetobacter baumannii strain

“…Analysis of the fragments acquired in strain A118::VA360 identified mobile genetic elements (ISAba14, ISKpn26, ISCR1 (IS91 family), IS26, IS1R and Tn3), antibiotic resistance genes such as sul1 qacE∆1 and aac(6')-lb-cr and six genes encoding efflux pumps, seven genes associated with metabolic pathways, hypothetical proteins, and intergenic regions from K. pneumoniae VA360 strain (Supplementary table S1). Among the genes associated with metabolic functions were cutA, which encodes for a dihydroorotate dehydrogenase [29,30], fieF, which encodes for a ferrous iron efflux system [31,32], and a fragment hpaX, a gene that encodes 4-hydroxyphenylacetate permease, an enzyme associated with 4-hydroxyphenylacetate (4-HPA) metabolism.…”