The ARR4 gene from Saccharomyces cerevisiae was highly homological with E. coli arsA. The defective nucleotide-binding domain of ARR4[G30R] exhibited negative dominance from the growth curve experiment, showing that ARR4 protein might act as a dimer in vivo. On the nonreducing gel, the purified 40 kDa ARR4 presented as monomer, dimer and oligomer conformational states. Besides, the chemical cross-linking experiments confirmed the positional size of dimeric ARR4. The metal ions of Co2+, Sb3+, As3+ and As5+ have not effect on the ATPase activity and ARR4 oligomerization. ARR4 exhibit a low level of Mg2+-ATPase activity in the range of 50-70 and 100-120 nmol/min/mg respectively as estimated by phosphate released and NADH-coupled assay. The maximal activity was obtained at a ratio of ATP:Mg2+ of 2:1 and the ATPase activity of ARR4[G30R] was about 50% of that of the ARR4 from both ATPase assays. In the presence of ATP or Mg2+, ARR4 has similar ratios of dimer and monomer. When incubated with Mg2+-ATP, ARR4 tended to form more dimer than with ATP and Mg2+ individually. ARR4[G30R] exhibited less dimer formation. Mixing ARR4 and ARR4[G30R] at a constant total protein concentration with different molar ratios (1:1, 1:2 and 1:4), a near linear relationship of activity versus amount of the ARR4 protein was observed. This observation suggests that ATP hydrolysis takes places in one ATP binding site independent of the other site of NBD. The proportional ATPase activities were consistent with the ratios of ARR4-ARR4[G30R] dimerization on the nonreducing gels. In conclusion, the conformational changes induced by Mg2+-ATP is related to the dimerization of ARR4 and both its NBDs would hydrolyze ATP independently.

The E. coli ArsA is involved in arsenic detoxification but the role of yArsA (ArsA homologue of Saccharomyces cerevisiae, encoded by YDL100C ORF) in yeast is still undefined. Disruption of YDL100C ORF is not lethal. To study the role of yArsA in oxidative tolerance, wild type and knock out strain were grown in presence or absence of 1 mM H2O2 and assayed the expression of anti-oxidation machanisms . The results show that molecular oxidation is higher and catalase activity is lower in KO compared with WT. It suggests that increased ROS and decreased catalase activity are the cause of cell death. Further analysis of the expression of ROS defense mechanisms by RT-PCR show that there is no significant difference in TRR1, GSH1, and SOD1 expression in WT and KO grown in presence of 1 mM H2O2 but the CTT1, TPS1, NTH1 expression in KO are less than WT grown under oxidative stress. GSH contents is consistent with the result of RT-PCR, and trehalose contents is higher in KO strain under oxidative stress. Loss of catalase activity and decreased efficiency of degrading trehalose suggest that the deficiency in activation of general stress response in KO when grown in the presence of H2O2. Therefore, yArsA would be involved in expressing the general stress response in oxidative tolerance.

YDL100cp is the ArsA homologous protein found in Saccharomyces cerevisiae. Previous studies show that deletion of YDL100c was not lethal but unable to grow at 40¢XC. To study the role of YDL100c in response to lethal heat shock, the wild type strain (WT) and YDL100c disrupted strain (KO) were exposed to 50¢XC for 30 min. The growth and survival rate of KO cells at 30¢XC after heat-shock was lower than that of WT cells, and the difference was complementated by introducing the plasmid carrying YDL100c. The oxidative stress has been shown to be involved in the heat-induced cell death in S. cerevisiae. Therefore, the intracellular molecular oxidation level, expression of antioxidant genes, trehalose accumulation, and glutathione (GSH) content were further examined. The intracellular molecular oxidation was increased in KO compared to WT when exposed to 50¢XC, suggesting heat-shock-induced cell death is related to oxidation of intracellular components. The results also demonstrated that both WT and KO had a decreased GSH content and trehalose accumulation after heat-shock, indicating that GSH and trehalose are not directly involved in the slow growth of KO after heat-shock. However, CTT1 expression is decreased in KO compared to WT when exposed to 50¢XC, suggesting that decreased CTT1 expression resulted in the increased intracellular oxidation and YDL100c is likely involved in the activation of CTT1 expression.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 140-160).

Reproduction de : Thèse de doctorat : Génie des procédés et de l'environnement : Toulouse, INPT : 2004. / Titre provenant de l'écran-titre. Bibliogr. 331 réf. Glossaire.

Thèse de doctorat : Aspects moléculaires et cellulaires de la biologie : Strasbourg 1 : 2007. Thèse de doctorat : Aspects moléculaires et cellulaires de la biologie : Université M. V. Lomonossov, Moscou : 2007. / Thèse soutenue en co-tutelle. Titre provenant de l'écran-titre. Bibliogr. p. 58-69.

Thèse doctorat : Aspects Moléculaires et Cellulaires de la Biologie : Strasbourg 1 : 2006. Thèse doctorat : Aspects Moléculaires et Cellulaires de la Biologie : M. Lomonossov - Moscou - Russie : 2006. / Thèse soutenue sur un ensemble de travaux. Thèse soutenue en co-tutelle. Titre provenant de l'écran-titre. Bibliogr. 9 p.

Reproduction de : Thèse de doctorat : Génie des procédés et de l'environnement : Toulouse, INPT : 2008. / Titre provenant de l'écran-titre. Bibliogr. 190 réf.

Thèse de doctorat : Aspects moléculaires et cellulaires de la biologie. Biologie moléculaire et cellulaire, génétique et virologie : Strasbourg 1 : 2007. Thèse doctorat : Aspects moléculaires et cellulaires de la biologie. Biologie moléculaire et cellulaire, génétique et virologie : Prague : 2007. / Thèse soutenue en co-tutelle. Titre provenant de l'écran-titre. Bibliogr. f. 99-115.

Thesis (Ph. D.)--University of Oregon, 2001. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 90-98). Also available for download via the World Wide Web; free to University of Oregon users.