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Thioredoxin reductase is required for growth and regulates entry into culmination of Dictyostelium discoideum
Author(s) -
Jeong SunYoung,
Choi ChangHoon,
Kim JiSun,
Park SeongJun,
Kang SaOuk
Publication year - 2006
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/j.1365-2958.2006.05329.x
Subject(s) - dictyostelium discoideum , biology , thioredoxin reductase , thioredoxin , microbiology and biotechnology , intracellular , ribonucleotide reductase , dictyostelium , biochemistry , protein subunit , mutant , enzyme , gene
Summary The thioredoxin system, consisting of thioredoxin, thioredoxin reductase and NADPH, has been well established to be critical for the redox regulation of protein function and signalling. To investigate the role of thioredoxin reductase (Trr) in Dictyostelium discoideum , we generated mutant cells that underexpress or overexpress Trr. Trr‐underexpressing cells exhibited severe defects in axenic growth and development. Trr‐overexpressing (Trr OE ) cells formed very tiny plaques on a bacterial lawn and had a lower rate of bacterial uptake. When developed in the dark, Trr OE cells exhibited a slugger phenotype, defined by a prolonged migrating slug stage. Like other slugger mutants, they were hypersensitive to ammonia, which has been known to inhibit culmination by raising the pH of intracellular acidic compartments. Interestingly, Trr OE cells showed defective acidification of intracellular compartments and decreased activity of vacuolar H + ‐ATPase which functions in the acidification of intracellular compartments. Moreover, biochemical studies revealed that the thioredoxin system can directly reduce the catalytic subunit of vacuolar H + ‐ATPase whose activity is regulated by reversible disulphide bond formation. Taken together, these results suggest that Dictyostelium Trr may be essential for growth and play a role in regulation of phagocytosis and culmination, possibly through the modulation of vacuolar H + ‐ATPase activity.