转运-信使RNA
转运-信使RNA(Transfer-messenger RNA,简称tmRNA,旧称10Sa RNA或Ssr RNA)是细菌中一种同时具有mRNA与tRNA功能与结构的RNA,此RNA本身如mRNA般具有编码区,3'端可如tRNA般由丙胺酸-tRNA合成酶加上一个丙胺酸[1],长度多介于320至400nt之间(少数结构退化者可能更短)[2],当细胞中的核糖体转译mRNA发生停滞时(包括mRNA突变而失去终止密码子等原因),tmRNA可与SmpB蛋白与EF-Tu等组合成一核糖核蛋白,并结合至核糖体空出的A位以启动反式转译(trans-translation),即将核糖体合成中的多肽转移至其3'端的丙胺酸上,以tmRNA的编码区为模板继续转译数个胺基酸后再遇到终止密码子而结束,转译出的蛋白末端带有丙胺酸和tmRNA编码的小段多肽序列(在大肠杆菌中为AANDENYALAA),此段序列通常会被细胞中的蛋白酶识别而将整个蛋白质降解[3],造成转译停滞的mRNA也会被水解移除[4]。
转运-信使RNA | |
---|---|
tmRNA (PDB 3IYR) | |
识别符 | |
代号 | tmRNA |
Rfam | RF00023 |
其他数据 | |
RNA类型 | 基因 |
几乎所有细菌基因组中皆具有编码tmRNA的基因[5],此RNA对某些细菌的生长相当重要,也有细菌在较为不利的生长条件下才需tmRNA[6]。tmRNA的合成途径和tRNA相似,转录后其5'端有一段序列需由核糖核酸酶P切割[1],3'端也有些序列需由核糖核酸酶T或核糖核酸酶PH切除[7][8],可连接丙胺酸的3'-CCA序列在某些物种是由基因编码,因此转录完成时即具备,某些物种则是在tmRNA转录与切割之后才由tRNA核苷酸转移酶加上[9]。另外α-变形菌、某些蓝绿菌与少数β-变形菌的tmRNA是由两段RNA组成的,其中一段RNA的3'端结合丙胺酸,另一段RNA则具编码序列,两者仅以碱基配对的氢键相互结合[10]。
tmRNA最早于1979年研究人员以电泳分析大肠杆菌RNA时与核糖核酸酶P上的M1RNA(旧称10Sb RNA)一起被发现,当时被命名为10Sa RNA[11] ,后续研究发现10Sa RNA具有常见于tRNA的假尿嘧啶核苷,且其3'端与tRNA的结构相似[12]。1995年始发现tmRNA还有编码蛋白序列的功能[13]。除细菌外,少数真核生物(雅各比虫与属卵菌的大豆疫霉菌)粒线体中的mtDNA也有编码tmRNA,但皆已失去与mRNA相似的编码区,仅存与tRNA相似的区域[9],还有数种藻类的质粒体中具有tmRNA,结构简化但仍具编码区和tRNA相似区[14]。
参见
编辑- 无终止密码子媒介式分解(NSD)、转译停滞分解(NGD):真核生物细胞解决核糖体停滞的机制。
参考文献
编辑- ^ 1.0 1.1 Komine Y, Kitabatake M, Yokogawa T, Nishikawa K, Inokuchi H. A tRNA-like structure is present in 10Sa RNA, a small stable RNA from Escherichia coli. Proceedings of the National Academy of Sciences of the United States of America. September 1994, 91 (20): 9223–7. PMC 44784 . PMID 7524073. doi:10.1073/pnas.91.20.9223.
- ^ Janssen BD, Hayes CS. The tmRNA ribosome-rescue system.. Adv Protein Chem Struct Biol. 2012, 86: 151–91. PMC 3358797 . PMID 22243584. doi:10.1016/B978-0-12-386497-0.00005-0.
- ^ Keiler KC, Waller PR, Sauer RT. Role of a peptide tagging system in degradation of proteins synthesized from damaged messenger RNA. Science. 1996, 271 (5251): 990–3. PMID 8584937. doi:10.1126/science.271.5251.990.
- ^ Keiler KC. Biology of trans-translation. Annual Review of Microbiology. 2008, 62: 133–51. PMID 18557701. doi:10.1146/annurev.micro.62.081307.162948.
- ^ Schönhuber W, Le Bourhis G, Tremblay J, Amann R, Kulakauskas S. Utilization of tmRNA sequences for bacterial identification.. BMC Microbiol. 2001, 1: 20. PMC 55692 . PMID 11560762. doi:10.1186/1471-2180-1-20.
- ^ Thibonnier M, Thiberge JM, De Reuse H. Ahmed N , 编. Trans-translation in Helicobacter pylori: essentiality of ribosome rescue and requirement of protein tagging for stress resistance and competence. PLOS ONE. 2008, 3 (11): e3810. PMC 2584231 . PMID 19043582. doi:10.1371/journal.pone.0003810.
- ^ Srivastava RA, Srivastava N, Apirion D. Characterization of the RNA processing enzyme RNase III from wild type and overexpressing Escherichia coli cells in processing natural RNA substrates. The International Journal of Biochemistry. 1992, 24 (5): 737–49. PMID 1375563. doi:10.1016/0020-711X(92)90007-N.
- ^ Li Z, Pandit S, Deutscher MP. 3' exoribonucleolytic trimming is a common feature of the maturation of small, stable RNAs in Escherichia coli. Proceedings of the National Academy of Sciences of the United States of America. 1998, 95 (6): 2856–61. PMC 19659 . PMID 9501180. doi:10.1073/pnas.95.6.2856.
- ^ 9.0 9.1 Hafez M, Burger G, Steinberg SV, Lang BF. A second eukaryotic group with mitochondrion-encoded tmRNA: in silico identification and experimental confirmation.. RNA Biol. 2013, 10 (7): 1117–24. PMC 3849159 . PMID 23823571. doi:10.4161/rna.25376.
- ^ Mao C, Bhardwaj K, Sharkady SM, Fish RI, Driscoll T, Wower J; et al. Variations on the tmRNA gene.. RNA Biol. 2009, 6 (4): 355–61. PMID 19617710. doi:10.4161/rna.6.4.9172.
- ^ Ray BK, Apirion D. Characterization of 10S RNA: a new stable rna molecule from Escherichia coli. Molecular & General Genetics. 1979, 174 (1): 25–32. PMID 384159. doi:10.1007/BF00433301.
- ^ Tyagi JS, Kinger AK. Identification of the 10Sa RNA structural gene of Mycobacterium tuberculosis. Nucleic Acids Research. 1992, 20 (1): 138. PMC 310338 . PMID 1371186. doi:10.1093/nar/20.1.138.
- ^ Tu GF, Reid GE, Zhang JG, Moritz RL, Simpson RJ. C-terminal extension of truncated recombinant proteins in Escherichia coli with a 10Sa RNA decapeptide. The Journal of Biological Chemistry. 1995, 270 (16): 9322–6. PMID 7536743. doi:10.1074/jbc.270.16.9322.
- ^ Gueneau de Novoa P, Williams KP. The tmRNA website: reductive evolution of tmRNA in plastids and other endosymbionts.. Nucleic Acids Res. 2004, 32 (Database issue): D104–8. PMC 308836 . PMID 14681369. doi:10.1093/nar/gkh102.