Lodato P, Alcaino J, Barahona S, Retamales P, Cifuentes V
Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
Appl Environ Microbiol. 2003 Aug;69(8):4676-82. doi: 10.1128/AEM.69.8.4676-4682.2003.
Xanthophyllomyces dendrorhous is one of the relevant sources of the carotenoid astaxanthin. In this paper, we describe for the first time cloning of unexpected cDNAs obtained from the crtI and crtYB genes of X. dendrorhous strain UCD 67-385. The cDNA of the crtI gene conserves 80 bp of the first intron, while the cDNA of the crtYB gene conserves 55 bp of the first intron and lacks 111 bp of the second exon. The crtI and crtYB RNAs could be spliced in alternative splice sites, which produced alternative transcripts which could not be translated to active CRTI and CRTYB proteins since they had numerous stop codons in their sequences. The ratio of mature mRNA to alternative mRNA for the crtI gene decreased as a function of the age of the culture, while the cellular content of carotenoids increased. It is possible that splicing to mature or alternative transcripts could regulate the cellular concentrations of phytoene desaturase and phytoene synthase-lycopene cyclase proteins, depending on the physiological or environmental conditions.
红法夫酵母是类胡萝卜素虾青素的相关来源之一。在本文中，我们首次描述了从红法夫酵母菌株UCD 67 - 385的crtI和crtYB基因中获得的意外cDNA的克隆。crtI基因的cDNA保留了第一个内含子的80 bp，而crtYB基因的cDNA保留了第一个内含子的55 bp，并且缺少第二个外显子的111 bp。crtI和crtYB RNA可以在可变剪接位点进行剪接，产生可变转录本，由于其序列中有许多终止密码子，这些转录本无法翻译成活性CRTI和CRTYB蛋白。crtI基因成熟mRNA与可变mRNA的比例随着培养时间的延长而降低，而类胡萝卜素的细胞含量增加。根据生理或环境条件，剪接成成熟或可变转录本可能会调节八氢番茄红素去饱和酶和八氢番茄红素合酶 - 番茄红素环化酶蛋白的细胞浓度。
