Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
Laboratorio de Proteómica, Centro Nacional de Biotecnología, C.S.I.C., Madrid, Spain.
mSphere. 2020 Apr 1;5(2):e00065-20. doi: 10.1128/mSphere.00065-20.
is a carotenogenic yeast with a singular metabolic capacity to produce astaxanthin, a valuable antioxidant pigment. This yeast can assimilate several carbon sources and sustain fermentation even under aerobic conditions. Since astaxanthin biosynthesis is affected by the carbon source, the study of carotenogenesis regulatory mechanisms is key for improving astaxanthin yield in This study aimed to elucidate the regulation of the metabolism of different carbon sources and the phenomenon of catabolic repression in this yeast. To this end, protein and transcript levels were quantified by iTRAQ (isobaric tags for relative and absolute quantification) and transcriptomic sequencing (RNA-seq) in the wild-type strain under conditions of glucose, maltose, or succinate treatment and in the mutant strains for genes , , and under conditions of glucose treatment. Alternative carbon sources such as maltose and succinate affected the relative abundances of 14% of the wild-type proteins, which were mainly grouped into the carbohydrate metabolism category, with the glycolysis/gluconeogenesis and citrate cycle pathways being the most highly represented pathways. Each mutant strain showed significant proteomic profile changes, affecting approximately 2% of the total proteins identified, compared to the wild-type strain under glucose treatment conditions. Similarly to the results seen with the alternative carbon sources, the changes in the mutant strains mainly affected carbohydrate metabolism, with glycolysis/gluconeogenesis and the pentose phosphate and citrate cycle pathways being the most highly represented pathways. Our results showed convergence between carbon assimilation and catabolic repression in the strains studied. Interestingly, indications of cooperative, opposing, and overlapping processes during catabolic regulation were found. We also identified target proteins of the regulatory processes, reinforcing the likelihood of catabolic repression at the posttranscriptional level. The conditions affecting catabolic regulation in are complex and suggest the presence of an alternative mechanism of regulation. The repressors Mig1, Cyc8, and Tup1 are essential elements for the regulation of the use of glucose and other carbon sources. All play different roles but, depending on the growth conditions, can work in convergent, synergistic, and complementary ways to use carbon sources and to regulate other targets for yeast metabolism. Our results reinforced the belief that further studies in are needed to clarify a specific regulatory mechanism at the domain level of the repressors as well as its relationship with those of other metabolic repressors, i.e., the stress response, to elucidate carotenogenic regulation at the transcriptomic and proteomic levels in this yeast.
是一种产类胡萝卜素酵母，具有独特的代谢能力，可生产有价值的抗氧化剂虾青素。这种酵母可以同化几种碳源，并在有氧条件下维持发酵。由于虾青素的生物合成受碳源的影响，因此研究类胡萝卜素生物合成的调控机制对于提高这种酵母的虾青素产量至关重要。本研究旨在阐明不同碳源代谢的调控以及这种酵母中分解代谢抑制的现象。为此，通过 iTRAQ（相对和绝对定量的同位素标记）和转录组测序（RNA-seq）定量测定了野生型菌株在葡萄糖、麦芽糖或琥珀酸盐处理条件下以及基因、和突变菌株在葡萄糖处理条件下的蛋白质和转录本水平。替代碳源，如麦芽糖和琥珀酸盐，影响了野生型蛋白的 14%的相对丰度，这些蛋白主要分为碳水化合物代谢类别，其中糖酵解/糖异生和柠檬酸循环途径是最具代表性的途径。与葡萄糖处理条件下的野生型菌株相比，每个突变菌株的蛋白质组图谱都发生了显著变化，影响了约 2%的总蛋白。与替代碳源的结果类似，突变菌株的变化主要影响碳水化合物代谢，其中糖酵解/糖异生和戊糖磷酸和柠檬酸循环途径是最具代表性的途径。我们的研究结果表明，在所研究的菌株中，碳同化和分解代谢抑制之间存在趋同。有趣的是，在分解代谢调节过程中发现了协同、相反和重叠过程的迹象。我们还鉴定了调节过程的靶蛋白，这加强了在转录后水平上进行分解代谢抑制的可能性。影响的分解代谢调节的条件很复杂，表明存在替代的调节机制。转录因子 Mig1、Cyc8 和 Tup1 是调节葡萄糖和其他碳源利用的必需元素。它们都发挥不同的作用，但根据生长条件，它们可以以趋同、协同和互补的方式共同作用，以利用碳源并调节酵母代谢的其他靶标。我们的研究结果强化了这样一种信念，即需要进一步研究，以阐明在该酵母中，在转录因子的调控域水平上的特定调控机制，以及其与其他代谢调控因子（即应激反应）的关系，以阐明在该酵母中类胡萝卜素的转录组和蛋白质组水平的调控。
