Saupe S, Stenberg L, Shiu K T, Griffiths A J, Glass N L
Department of Botany, University of British Columbia, Vancouver, Canada.
Mol Gen Genet. 1996 Jan 15;250(1):115-22. doi: 10.1007/BF02191831.
The 293-amino acid mt A-1 ORF of the A mating-type idiomorph of Neurospora crassa is multifunctional. It confers A mating identity and is responsible for heterokaryon incompatibility. The goal of this study was to dissect the functional regions of mt A-1. New mutants of mt A-1 selected for loss of the incompatibility function were obtained. One new mutant, A(m)99, was partially fertile as a maternal parent. This is the first time that fertility and incompatibility functions have been separated for the A idiomorph. In this mutant, the mt A-1 ORF is truncated after the first 85 amino acids, indicating that this N-terminal region is minimally sufficient for female fertility. A series of deletion constructs and frameshift alleles of mt A-1 was obtained and tested for male-mating activity and vegetative incompatibility in transformation experiments. These experiments showed that a region from position 1 to 111 is sufficient to confer incompatibility, while amino acids from position 1 to 227 are required for mating activity. A transcriptional analysis of mt A-1 showed that the mRNA is expressed both before and after fertilization. This, together with the phenotype of the A(m)99 mutant, suggests a post-fertilization function for mt A-1.
粗糙脉孢菌A交配型特异型的293个氨基酸的线粒体A-1开放阅读框具有多种功能。它赋予A交配型身份，并负责异核体不相容性。本研究的目的是剖析线粒体A-1的功能区域。获得了因不相容性功能丧失而筛选出的线粒体A-1新突变体。一个新突变体A(m)99作为母本部分可育。这是首次将A特异型的育性和不相容性功能分离。在这个突变体中，线粒体A-1开放阅读框在前85个氨基酸之后被截断，这表明该N端区域对于雌性育性是最低限度足够的。获得了一系列线粒体A-1的缺失构建体和移码等位基因，并在转化实验中测试了它们的雄性交配活性和营养体不相容性。这些实验表明，第1至111位的区域足以赋予不相容性，而第1至227位的氨基酸是交配活性所必需的。对线粒体A-1的转录分析表明，该mRNA在受精前后均有表达。这与A(m)99突变体的表型一起，提示线粒体A-1具有受精后功能。
