Palma Margarida, Dias Paulo Jorge, Roque Filipa de Canaveira, Luzia Laura, Guerreiro Joana Fernandes, Sá-Correia Isabel
iBB-Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, 1049-001, Lisbon, Portugal.
BMC Genomics. 2017 Jan 13;18(1):75. doi: 10.1186/s12864-016-3443-2.
The food spoilage yeast species Zygosaccharomyces bailii exhibits an extraordinary capacity to tolerate weak acids, in particular acetic acid. In Saccharomyces cerevisiae, the transcription factor Haa1 (ScHaa1) is considered the main player in genomic expression reprogramming in response to acetic acid stress, but the role of its homologue in Z. bailii (ZbHaa1) is unknown.
In this study it is demonstrated that ZbHaa1 is a ScHaa1 functional homologue by rescuing the acetic acid susceptibility phenotype of S. cerevisiae haa1Δ. The disruption of ZbHAA1 in Z. bailii IST302 and the expression of an extra ZbHAA1 copy confirmed ZbHAA1 as a determinant of acetic acid tolerance. ZbHaa1 was found to be required for acetic acid stress-induced transcriptional activation of Z. bailii genes homologous to ScHaa1-target genes. An evolutionary analysis of the Haa1 homologues identified in 28 Saccharomycetaceae species genome sequences, including Z bailii, was carried out using phylogenetic and gene neighbourhood approaches. Consistent with previous studies, this analysis revealed a group containing pre-whole genome duplication species Haa1/Cup2 single orthologues, including ZbHaa1, and two groups containing either Haa1 or Cup2 orthologues from post-whole genome duplication species. S. cerevisiae Cup2 (alias Ace1) is a transcription factor involved in response and tolerance to copper stress. Taken together, these observations led us to hypothesize and demonstrate that ZbHaa1 is also involved in copper-induced transcriptional regulation and copper tolerance.
The transcription factor ZbHaa1 is required for adaptive response and tolerance to both acetic acid and copper stresses. The subfunctionalization of the single ancestral Haa1/Cup2 orthologue that originated Haa1 and Cup2 paralogues after whole genome duplication is proposed.
食品腐败酵母菌种拜耳接合酵母表现出非凡的耐弱酸能力，尤其是乙酸。在酿酒酵母中，转录因子Haa1（ScHaa1）被认为是响应乙酸胁迫时基因组表达重编程的主要参与者，但其在拜耳接合酵母中的同源物（ZbHaa1）的作用尚不清楚。
在本研究中，通过挽救酿酒酵母haa1Δ的乙酸敏感性表型，证明ZbHaa1是ScHaa1的功能同源物。在拜耳接合酵母IST302中破坏ZbHAA1以及额外拷贝ZbHAA1的表达证实ZbHAA1是乙酸耐受性的决定因素。发现ZbHaa1是乙酸胁迫诱导的与ScHaa1靶基因同源的拜耳接合酵母基因转录激活所必需的。使用系统发育和基因邻域方法对包括拜耳接合酵母在内的28个酵母科物种基因组序列中鉴定出的Haa1同源物进行了进化分析。与先前的研究一致，该分析揭示了一个包含全基因组复制前物种Haa1/Cup2单一直向同源物的组，包括ZbHaa1，以及两个包含全基因组复制后物种的Haa1或Cup2直系同源物的组。酿酒酵母Cup2（别名Ace1）是一种参与铜胁迫响应和耐受的转录因子。综上所述，这些观察结果使我们推测并证明ZbHaa1也参与铜诱导的转录调控和铜耐受性。
转录因子ZbHaa1是对乙酸和铜胁迫的适应性反应和耐受性所必需的。提出了在全基因组复制后起源于Haa1和Cup2旁系同源物的单一祖先Haa1/Cup2直系同源物的亚功能化。
