十字花科黑腐病菌中存在tRNA衍生片段(tRF)的证据

The Evidence that tRNA-derived Fragment(tRF) Existed in Xanthomonas campestris pathovar campestris

tRNA衍生片段(tRNA-derived fragment, tRF)是一种由内切核糖核酸酶将初级tRNA (primary tRNA)或成熟tRNA分子剪切后形成的长度为14~30 nt (核苷酸)的稳定的RNA片段。研究表明,tRF广泛存在于各种真核生物中,它们既可以作为信号分子,又可以作为基因表达的调控因子,在细胞的各种生理过程中发挥重要的调控作用。但至今除了在大肠杆菌(Escherichia coli)和沃氏富盐菌(Haloferax volcanii)中发现了tRF外,在其他原核生物中未见有关tRF的报道。本研究采用高灵敏度的Northern杂交技术对十字花科黑腐病菌(Xanthomonas campestris pv. campestris, Xcc)的苏氨酸-tRNA (threonine-tRNA, tRNAThr)和甲硫氨-tRNA (methionine-tRNA, tRNAMet)进行了检测。结果显示,除了检测到全长的成熟tRNAThr和tRNAMet外,还检测到多个丰度各异的稳定的tRF,而且一些tRF的产生受营养胁迫的诱导。此外,我们还发现,编码tRNAMet的基因XC4381已经退化为非编码RNA基因。本研究证明了tRF在Xcc中的存在,为深入研究tRF的功能,特别是在Xcc致病中的作用奠定了基础。

tRNA-derived fragments(tRFs) are 14~30 nt(nucleotide) stable RNA molecules generated from the primary tRNA or mature tRNA by endoribonuclease digestion. It has shown that tRFs are widely distributed in eukaryotes and play important roles in various physiological process through being used as a signal molecule or acting as gene expression regulator. However, up to date, the existence of tRF has only been reported in Escherichia coli and Haloferax volcanii, whether tRF up to date existed in other prokaryotes is unclear. In this work, the transcripts of threonine-tRNA(tRNAThr) and methionine-tRNA(tRNAMet) were detected in the phytopathogenic bacterial pathogen Xanthomonas campestris pv. campestris(Xcc), by using high sensitive Northern Blotting. The results showed that in addition to the mature tRNAThrand tRNAMet, several tRF signal bands were detected, and that the production of some tRFs was induced by nutrient deficiency. In addition, we found that the tRNAMetgene XC4381 may have degenerated to become a non-coding RNA gene. Our study for the first time provides evidence to demonstrate the existence of tRF in Xcc, and the first step towards the understanding of the function, especially the role of tRF in the virulence of Xcc.