title: Characterization ofcis-elements in the promoter oftrz2encodingSchizosaccharomyces pombemitochondrial tRNA 3'-end processing enzyme.
abstract: The endonuclease tRNase Z is responsible for the 3'-end processing of tRNA precursors, which is one of the essential steps in tRNA maturation. The fission yeastSchizosaccharomyces pombecontains two essential tRNase ZLgenes (trz1andtrz2) involved in nuclear and mitochondrial tRNA 3'-end processing, respectively. Our previous studies suggest thattrz2is expressed at a very low level. Here we report characterization of thetrz2promoter. UsinglacZas a reporter, we show that thetrz2promoter contains a HomolD box and a very weak diverged TATA element. The HomolD box is usually found in the promoters ofS. pomberibosomal protein genes.lacZreporter assays suggest that the HomolD box regulates the expression of bothtrz2and the ribosomal protein generps2501, which are arranged head-to-head on opposite strands. Overexpression of Rrn7, a candidate HomolD box-binding protein, up-regulates expression oflacZunder the control of thetrz2promoter or therps2501promoter. Functional complementation studies suggest that the TATA-like element is essential fortrz2expression, whereas the HomolD box may play a nonessential regulatory role. We also demonstrate that a 57 nt negative regulatory element (NRE) located between the HomolD box and the TATA-like element represses the expression oflacZunder the control of thetrz2promoter. Our results suggest that the low-leveltrz2expression may arise from a low level of transcription caused by lack of a strong TATA box and the NRE. Our analysis also suggests thattrz2andrps2501may be coregulated by the HomolD box.
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, PR China.
authors.forename: Jinyu
authors.initials: J
authors.lastname: Liu
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, PR China.
authors.forename: Linting
authors.initials: L
authors.lastname: Huang
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, PR China.
authors.forename: Yirong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, School of Life Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, PR China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
keywords: HomolD box; TATA-like element; promoter; transcription