新研究為生命的第一個遺傳分子可能是什么樣的提供了線索。生物都靠由DNA組成的基因和蛋白質(zhì)酶來實現(xiàn)細胞功能的。大約40年前,，研究人員提出“RNA世界”的假說,，他們認為在生命的最初，RNA可能出現(xiàn)在基因和酶之前,，因為RNA既能催化反應也包含遺傳信息,，所以第一個遺傳分子是能自我拷貝的RNA。雖然自然界中沒有能將RNA分子連接起來的RNA酶,，而這是RNA世界的一個關鍵的必要條件,，但是研究人員合成了這樣一個酶。現(xiàn)在Michael P. Robertson和William G. Scott確定出這個被稱為“連接核酶”的結(jié)構(gòu),。其活性點的結(jié)構(gòu)提示，該核酶用已知的自然界核酶所用的生物化學戰(zhàn)略,。一篇相關的研究評述進一步討論了這些發(fā)現(xiàn),。
部分英文原文：
Science 16 March 2007:
Vol. 315. no. 5818, pp. 1549 - 1553
DOI: 10.1126/science.1136231
The Structural Basis of Ribozyme-Catalyzed RNA Assembly
Michael P. Robertson and William G. Scott*
Life originated, according to the RNA World hypothesis, from self-replicating ribozymes that catalyzed ligation of RNA fragments. We have solved the 2.6 angstrom crystal structure of a ligase ribozyme that catalyzes regiospecific formation of a 5' to 3' phosphodiester bond between the 5'-triphosphate and the 3'-hydroxyl termini of two RNA fragments. Invariant residues form tertiary contacts that stabilize a flexible stem of the ribozyme at the ligation site, where an essential magnesium ion coordinates three phosphates. The structure of the active site permits us to suggest how transition-state stabilization and a general base may catalyze the ligation reaction required for prebiotic RNA assembly.
The Center for the Molecular Biology of RNA and Department of Chemistry and Biochemistry, Robert L. Sinsheimer Laboratories, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
* To whom correspondence should be addressed. E-mail: [email protected]
