PubMed · 7532258
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H M Shapiro. 1994. Cell membrane potential analysis.. https://doi.org/10.1016/s0091-679x(08)61713-6
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Yeasts are beneficial microorganisms for human society and are utilized for academic and industrial purposes. For academic purposes, S. cerevisiae is a well-investigated model for studying eukaryotic cellular processes. For industrial purposes, S. pastorianus, which has a hybrid genome of S. cerevisiae and S. eubayanus, has been served for lager beer production. During fermentation, S. pastorianus produces ~7% of EtOH, which induces plasma membrane (PM)/cell wall stress in yeast. Therefore, S. pastorianus may experience PM stress and adapt to the self-forming environment during fermentation. However, how yeast adapts to PM stress remains unclear. Here, we investigated the temporal cellular responses of S. cerevisiae and S. pastorianus during adaptation to PM stresses by time-resolved mRNA-seq analysis. Our data showed different transcriptional phenotypes between S. cerevisiae and S. pastorianus during adaptation. The results may reflect the distinct nature of the two yeasts that have evolved in different nutritional environments. The dataset presented here would provide a promising resource for studying the characteristic nature of these differentially domesticated yeasts upon PM stresses.
We have taken advantage of cysteine mutants described previously (Petrov, V. V., and Slayman, C. W. (1995) J. Biol. Chem. 270, 28535-28540) to map the sites at which N-ethylmaleimide (NEM) reacts with the plasma-membrane H+ATPase (PMA)1 of Saccharomyces cerevisiae. When membrane vesicles containing the ATPase were incubated with NEM, six of nine mutants with single cysteine substitutions showed sensitivity similar to the wild-type enzyme. By contrast, C221A and C532A were inactivated more slowly than the wild-type control, and the C221, 532A double mutant was completely resistant, indicating that Cys-221 and Cys-532 are NEM-reactive residues. In the presence of 10 mM MgADP, the wild-type ATPase was partially protected against NEM; parallel experiments with the C221A and C532A mutants showed that the protection occurred at Cys-532, located in or near the nucleotide-binding site. Unexpectedly, the inactivation of the C409A ATPase was approximately 4-fold more rapid than in the case of the wild-type enzyme. Experiments with double mutants made it clear that this resulted from an acidic shift in pKa and a consequent acceleration of the reaction rate at Cys-532. One simple interpretation is that substitution of Cys-409 leads to a local conformational change within the central hydrophilic domain. Consistent with this idea, the reaction of fluorescein 5'-isothiocyanate at Lys-474 was also stimulated approximately 3. 5-fold by the C409A mutation. Taken together, the results of this study provide new information about the reactivity of individual Cys residues within the ATPase and pave the way to tag specific sites for structural and functional studies of the enzyme.
The nonerythroid expression of the Duffy blood group protein (gp-Fy) was confined to certain cell types. Immunocytochemistry studies of the kidney showed gp-Fy in the endothelium of glomeruli, peritubular capillaries, vasa recta, and the principal cells (epithelial) of collecting ducts. Gp-Fy was also produced in the endothelial cells of large venules and epithelial cells (type-I) of pulmonary alveoli. In the thyroid, only the endothelial cells of capillaries produced gp-Fy. In the spleen, the endothelial cells of capillaries, high endothelial venule, and sinusoids produced abundant gp-Fy. Ultrastructural studies showed that apical and basolateral plasma membrane domains, including caveolae, had gp-Fy. Immunoblot analysis showed substantially less gp-Fy in nonerythroid cells than in erythrocytes. Moreover, the analyzed nonerythroid organs of Duffy-negative individuals did not produce more gp-Fy to compensate for the lack of this protein in their erythrocytes. The nucleotide sequence and the size of kidney mRNA from a Duffy-positive individual were the same as that of bone marrow. It is assumed, therefore, that nonerythroid Duffy protein is the product of the same gene as that of bone marrow. This notion is reinforced by the fact that nonerythroid and erythroid gp-Fy have the same antigenic domains.