Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109-0606, USA.
RNA. 2011 Aug;17(8):1441-50. doi: 10.1261/rna.2737511. Epub 2011 Jun 10.
Ribonuclease P (RNase P) is an essential endoribonuclease that catalyzes the cleavage of the 5' leader of pre-tRNAs. In addition, a growing number of non-tRNA substrates have been identified in various organisms. RNase P varies in composition, as bacterial RNase P contains a catalytic RNA core and one protein subunit, while eukaryotic nuclear RNase P retains the catalytic RNA but has at least nine protein subunits. The additional eukaryotic protein subunits most likely provide additional functionality to RNase P, with one possibility being additional RNA recognition capabilities. To investigate the possible range of additional RNase P substrates in vivo, a strand-specific, high-density microarray was used to analyze what RNA accumulates with a mutation in the catalytic RNA subunit of nuclear RNase P in Saccharomyces cerevisiae. A wide variety of noncoding RNAs were shown to accumulate, suggesting that nuclear RNase P participates in the turnover of normally unstable nuclear RNAs. In some cases, the accumulated noncoding RNAs were shown to be antisense to transcripts that commensurately decreased in abundance. Pre-mRNAs containing introns also accumulated broadly, consistent with either compromised splicing or failure to efficiently turn over pre-mRNAs that do not enter the splicing pathway. Taken together with the high complexity of the nuclear RNase P holoenzyme and its relatively nonspecific capacity to bind and cleave mixed sequence RNAs, these data suggest that nuclear RNase P facilitates turnover of nuclear RNAs in addition to its role in pre-tRNA biogenesis.
核糖核酸酶 P（RNase P）是一种必需的内切核酸酶，能催化前 tRNA 的 5' 前导序列的切割。此外，在各种生物体中已鉴定出越来越多的非 tRNA 底物。RNase P 的组成不同，因为细菌 RNase P 包含催化 RNA 核心和一个蛋白质亚基，而真核核 RNase P 保留了催化 RNA，但至少有九个蛋白质亚基。额外的真核蛋白亚基可能为 RNase P 提供了额外的功能，一种可能性是额外的 RNA 识别能力。为了研究体内可能存在的额外 RNase P 底物的范围，使用链特异性、高密度微阵列来分析在酿酒酵母的核 RNase P 的催化 RNA 亚基突变时哪些 RNA 积累。结果表明，大量的非编码 RNA 积累，表明核 RNase P 参与通常不稳定的核 RNA 的周转。在某些情况下，积累的非编码 RNA 与丰度相应降低的转录本是反义的。含有内含子的前 mRNA 也广泛积累，这与剪接受损或未能有效周转不进入剪接途径的前 mRNA 一致。考虑到核 RNase P 全酶的高度复杂性及其结合和切割混合序列 RNA 的相对非特异性能力，这些数据表明核 RNase P 除了在前 tRNA 生物发生中发挥作用外，还促进核 RNA 的周转。
