近日，國(guó)際著名雜志Biochemical Journal 在線刊登了了上海生科院生化與細(xì)胞所王恩多課題組的最新研究成果“A naturally occurring nonapeptide functionally compensates the CP1 domain of leucyl-tRNA synthetase to modulate aminoacylation activity”,，文章中,，研究者在運(yùn)動(dòng)型支原體無編校結(jié)構(gòu)域的LeuRS的催化機(jī)理獲得了進(jìn)展。
氨基酰tRNA合成酶(aaRS)是蛋白質(zhì)翻譯系統(tǒng)的重要組成部分,，其主要負(fù)責(zé)為蛋白質(zhì)的生物合成提供原料：氨基酰-tRNA,。aaRS反應(yīng)的精確性對(duì)正確翻譯遺傳信息致關(guān)重要。亮氨酰-tRNA合成酶（LeuRS）在進(jìn)化過程中募集了插入合成氨基酰-tRNA活性中心的一個(gè)編校結(jié)構(gòu)域（Connective peptide,， CP1）,，在該結(jié)構(gòu)域內(nèi)生成的錯(cuò)誤氨基酰-tRNA被水解，從而保證催化反應(yīng)的專一性,。目前已知的LeuRS中只有來自運(yùn)動(dòng)型支原體（Mycoplasma mobile）的LeuRS（MmLeuRS）無CP1,，而代之以含有九個(gè)氨基酸殘基的九肽（MmLinker）。
王恩多研究組的譚敏博士和博士研究生閆衛(wèi)等發(fā)現(xiàn),，MmLeuRS缺失了依賴tRNA的編校功能,；MmLinker對(duì)MmLeuRS的氨基酰化活力致關(guān)重要,，它可以功能性地代償其它物種LeuRS的CP1在氨基?；磻?yīng)中的作用。來自大腸桿菌的LeuRS的CP1（EcCP1）可以在MmLeuRS中代替MmLinker發(fā)揮作用,，EcCP1融合進(jìn)MmLeuRS可賦予MmLeuRS轉(zhuǎn)移后編?；盍砭S持催化反應(yīng)的專一性。通過無CP1的MmLeuRS的研究發(fā)現(xiàn)：LeuRS的轉(zhuǎn)移前編?；盍κ窃诤铣砂被?tRNA的結(jié)構(gòu)域進(jìn)行的,。
該論文為aaRS的模塊融合進(jìn)化假說提供了直接的證據(jù)，同時(shí)也為L(zhǎng)euRS轉(zhuǎn)移前編校的分子機(jī)制的研究提供了線索,。
該項(xiàng)研究工作得到了國(guó)家科技部,、國(guó)家基金委、中國(guó)科學(xué)院的資助,。（生物谷Bioon.com）
doi:10.1042/BJ20111925
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A naturally occurring nonapeptide functionally compensates the CP1 domain of leucyl-tRNA synthetase to modulate aminoacylation activity
Min Tan, Wei Yan, Ru-Juan Liu, Meng Wang, Xin Chen, Xiao-Long Zhou and En-Duo Wang
Aminoacyl-tRNA synthetases (aaRSs) establish the rules of the genetic code by catalyzing the formation of aminoacyl-tRNA. The quality control for aminoacylation reaction is achieved by editing activity, which is usually carried out by a discrete editing domain. For leucyl-tRNA synthetase (LeuRS), the connective peptide 1 (CP1) domain is the editing domain responsible for hydrolyzing mis-charged tRNA. The CP1 domain is universally present in LeuRSs except LeuRS from Mycoplasma mobile (MmLeuRS). The substitute of CP1 in MmLeuRS is a nonapeptide (MmLinker). We show here that the MmLinker, which is critical for aminoacylation activity of MmLeuRS, could confer remarkable tRNA charging activity to the inactive CP1-deleted LeuRS from Escherichia coli (EcLeuRS) and Aquifex aeolicus (AaLeuRS). Furthermore, CP1 from EcLeuRS could functionally compensate the MmLinker and endow MmLeuRS with post-transfer editing capability. These investigations provide a mechanistic framework for the modular construction of aaRSs and their coordination to achieve catalytic efficiency and fidelity. These results also show that the pre-transfer editing function of LeuRS originates from its conserved synthetic domain, and shed light on future mechanism study.
