Roles of putative His-to-Asp signaling modules HPT-1 and RRG-2, on viability and sensitivity to osmotic and oxidative stresses in Neurospora crassa

• Published in: Current genetics 2007-03, Vol.51 (3), p.197-208
• Main Authors: Banno, Shinpei, Noguchi, Rieko, Yamashita, Kazuhiro, Fukumori, Fumiyasu, Kimura, Makoto, Yamaguchi, Isamu, Fujimura, Makoto
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs - genetics; Amino Acid Sequence; Amino Acid Substitution - genetics; Aminoimidazole Carboxamide - analogs & derivatives; Aminoimidazole Carboxamide - pharmacology; Aspartic Acid - genetics; Aspartic Acid - physiology; Butyl hydroperoxide; Fungal Proteins - genetics; Fungal Proteins - physiology; Fungicides, Industrial - pharmacology; Genetic crosses; Histidine; Histidine - genetics; Histidine - physiology; Histidine Kinase; Histidine phosphotransfer; Hydantoins - pharmacology; MAP kinase; Mitogen-Activated Protein Kinases - genetics; Mitogen-Activated Protein Kinases - physiology; Molecular Sequence Data; Mutants; Mutation; Neurospora crassa; Neurospora crassa - drug effects; Neurospora crassa - genetics; Neurospora crassa - growth & development; Neurospora crassa - physiology; Osmoregulation; Osmotic Pressure - drug effects; Oxidative stress; Oxidative Stress - drug effects; Oxidative Stress - genetics; Oxidative Stress - physiology; Point Mutation; Protein Kinases - genetics; Response regulator; Signal Transduction - drug effects; Signal Transduction - genetics; Signal Transduction - physiology; Two-component signal transduction; Yeasts
• ISSN: 0172-8083; 1432-0983
• DOI: 10.1007/s00294-006-0116-8

Neurospora crassa has a putative histidine phosphotransfer protein (HPT-1) that transfers signals from 11 histidine kinases to two putative response regulators (RRG-1 and RRG-2) in its histidine-to-aspartate phosphorelay system. The hpt-1 gene was successfully disrupted in the os-2 (MAP kinase gene) mutant, but not in the wild-type strain in this study. Crossing the resultant hpt-1; os-2 mutants with the wild-type or os-1 (histidine kinase gene) mutant strains produced no progeny with hpt-1 or os-1; hpt-1 mutation, strongly suggesting that hpt-1 is essential for growth unless downstream OS-2 is inactivated. hpt-1 mutation partially recovered the osmotic sensitivity of os-2 mutants, implying the involvement of yeast Skn7-like RRG-2 in osmoregulation. However, the rrg-2 disruption did not change the osmotic sensitivity of the wild-type strain and the os-2 mutant, suggesting that rrg-2 did not participate in the osmoregulation. Both rrg-2 and os-2 single mutation slightly increased sensitivity to t-butyl hydroperoxide, and rrg-2 and hpt-1 mutations increased the os-2 mutant's sensitivity. Although OS-1 is considered as a positive regulator of OS-2 MAP kinase, our results suggested that HPT-1 negatively regulated downstream MAP kinase cascade, and that OS-2 and RRG-2 probably participate independently in the oxidative stress response in N. crassa.