Phaffia rhodozyma is a basidiomycetous yeast that synthesizes astaxanthin (ASX), which is a powerful and highly valuable antioxidant carotenoid pigment. P. rhodozyma cells accrue ASX and gain an intense red-pink coloration when faced with stressful conditions such as nutrient limitations (e.g., nitrogen or copper), the presence of toxic substances (e.g., antimycin A), or are affected by mutations in the genes that are involved in nitrogen metabolism or respiration. Since cellular accrual of ASX occurs under a wide variety of conditions, this yeast represents a valuable model for studying the growth conditions that entail oxidative stress for yeast cells. Recently, we proposed that ASX synthesis can be largely induced by conditions that lead to reduction–oxidation (redox) imbalances, particularly the state of the NADH/NAD+ couple together with an oxidative environment. In this work, we review the multiple known conditions that elicit ASX synthesis expanding on the data that we formerly examined. When considered alongside the Mitchell's chemiosmotic hypothesis, the study served to rationalize the induction of ASX synthesis and other adaptive cellular processes under a much broader set of conditions. Our aim was to propose an underlying mechanism that explains how a broad range of divergent conditions converge to induce ASX synthesis in P. rhodozyma. The mechanism that links the induction of ASX synthesis with the occurrence of NADH/NAD+ imbalances may help in understanding how other organisms detect any of a broad array of stimuli or gene mutations, and then adaptively respond to activate numerous compensatory cellular processes.

中文翻译：

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破译酵母红法夫酵母对环境、营养和遗传线索做出适应性反应的机制


红法夫酵母是一种担子菌酵母，可合成虾青素 (ASX)，虾青素是一种强大且极具价值的抗氧化类胡萝卜素色素。当面临营养限制（例如氮或铜）、有毒物质（例如抗霉素 A）的存在或受到细胞突变的影响等应激条件时，红酵母细胞会积累 ASX 并获得强烈的红粉色。参与氮代谢或呼吸作用的基因。由于 ASX 的细胞增殖发生在多种条件下，因此这种酵母代表了研究酵母细胞氧化应激生长条件的有价值的模型。最近，我们提出 ASX 合成很大程度上是由导致氧化还原 (redox) 失衡的条件诱导的，特别是 NADH/NAD+ 配对的状态与氧化环境。在这项工作中，我们回顾了多种已知条件，这些条件引发了 ASX 合成，扩展了我们之前检查的数据。当与米切尔的化学渗透假说一起考虑时，这项研究有助于在更广泛的条件下合理化 ASX 合成和其他适应性细胞过程的诱导。我们的目的是提出一种潜在机制，解释广泛的不同条件如何汇聚以诱导红酵母中 ASX 的合成。将 ASX 合成的诱导与 NADH/NAD+ 失衡的发生联系起来的机制可能有助于理解其他生物体如何检测任何广泛的刺激或基因突变，然后适应性地响应以激活众多的补偿性细胞过程。