Analysis of the signal transduction of the formation of subcellular organelles, peroxisomes

热带假丝酵母是一种可产生分裂的二倍体酵母菌，其特点是能够利用正构烷烃作为唯一的碳和能量来源。热带镰刀菌在吸收正构烷烃的过程中，胞内结构发生变化，产生大量过氧化物酶体。过氧化物酶体是一种多功能的、单膜结合的细胞器，存在于大多数真核细胞中。随着过氧化物酶体的增殖，在正构烷烃生长的细胞中，过氧化物酶体酶的活性被诱导。另一方面，在葡萄糖生长的细胞中，它们的合成速度很低，或者根本不合成。这种现象被称为葡萄糖抑制。异柠檬酸裂解酶（ICL）是定位于过氧化物酶体的乙醛酸循环的关键酶，受葡萄糖抑制的控制。利用葡萄糖抑制机制控制的酿酒酵母菌启动子寻找基因表达下调的顺式调控元件。此外，还发现了与酿酒酵母葡萄糖抑制的遗传调控有关的多种反式作用因子。upr -ICL介导的热带镰刀菌转录在酿酒酵母中仍然具有葡萄糖抑制作用，这表明在这两种酵母菌株中普遍存在类似的ICL基因调控机制。在乙酸培养基中分离出一种突变体，该突变体不能抑制upr - icl介导的基因表达，并分离出补充该突变的基因（FILl）。fill被破坏的fill零突变体不能在乙酸或乙醇上生长，并且在酿酒酵母中也出现了ICLl编码的异柠檬酸裂解酶的抑制。Fillp（230个氨基酸）的氨基酸序列与原核生物的核糖体再循环因子（RRFs）相似。与原核生物的RRFs相比，filip具有n端46个氨基酸的延伸，可以作为线粒体靶向序列。对DELTAfil 1菌株进行亚细胞分离，结果表明，该菌株线粒体部分的蛋白质成分与野生型菌株不同，但与氯霉素处理的细胞或rho相似。细胞。这些结果表明，filp是酿酒酵母线粒体中蛋白质合成所必需的。结果表明，当线粒体呼吸链缺乏时，线粒体与细胞核之间存在一种通讯途径，抑制编码乙醛酸循环和糖异生途径关键酶的基因表达。少

Candida tropicalis is an asporogenic diploid yeast which is characterized by its ability to utilize n-alkanes as a sole carbon and energy source. In assimilating n-alkanes, C.tropicalis shows a change in its intracellular structure by proliferating a large number of peroxisomes. Peroxisomes are versatile, single-membrane-bound organelles occurring in most of eukaryotic cells. Concomitant with peroxisome proliferation, the activities of peroxisomal enzymes are induced in n-alkane-grown cells. On the other hand, they are synthesized at low rate or not at all in glucose-grown cells. This phenomenon is called as glucose repression. Isociterate lyase (ICL), a key enzyme of the glyoxylate cycle being localized in peroxisomes, is under the control of glucose repression. Promoters of Saccharomyces cerevisiae controlled by the glucose repression mechanism were used to search for cis-regulatory elements responsible for derepression of gene expression. Various trans-acting factors which are invol … More ved in the genetic regulation of the glucose repression in S.cerevisiae, were also identified. The fact that UPR-ICL-mediated transcription of C.tropicalis is still glucose-repressive in S.cerevisiae demonstrates that similar mechanisms are commonly existing in both of the yeast strains concerning the regulation of ICL gene. A mutant was isolated that failed to derepress the UPR-ICL-mediated gene expression in acetate medium, and the gene (FILl) that complemented this mutation was isolated. The fill null mutant in which FILl is disrupted could not grow on acetate or ethanol, and the derepression of the isocitrate lyase encoded by ICLl in S.cerevisiae was also defected. The amino acid sequence of Fillp (230 amino acids) showed similarity to ribosome recycling factors (RRFs) of prokaryotes. Compared to prokaryotic RRFs, Fil ip had an N-terminal 46 amino acid extension which was shown to be able to function as a mitochondrial targeting sequence. The subcellular fractionation of the DELTAfil 1 strain showed that protein constituents of the mitochondrial fraction of the DELTAfil 1 strain differed from those of the wild type strain, but resembled those of chloramphenicol-treated cells or rho。 cells. These results suggest that Fillp is necessary for protein synthesis in mitochondria of S.cerevisiae. The results indicate the presence of a communication pathway between mitochondria and the nucleus which represses expression of genes encoding the key enzymes of the glyoxylate cycle and gluconeogenic pathway when there is a deficiency in the mitochondrial respiratory chain. Less