Eriani G, Delarue M, Poch O, Gangloff J, Moras D
Laboratoires de Biochimie, IBMC du CNRS, Strasbourg, France.
Nature. 1990 Sep 13;347(6289):203-6. doi: 10.1038/347203a0.
The aminoacyl-transfer RNA synthetases (aaRS) catalyse the attachment of an amino acid to its cognate transfer RNA molecule in a highly specific two-step reaction. These proteins differ widely in size and oligomeric state, and have limited sequence homology. Out of the 18 known aaRS, only 9 referred to as class I synthetases (GlnRS, TyrRS, MetRS, GluRS, ArgRS, ValRS, IleRS, LeuRS, TrpRS), display two short common consensus sequences ('HIGH' and 'KMSKS') which indicate, as observed in three crystal structures, the presence of a structural domain (the Rossman fold) that binds ATP. We report here the sequence of Escherichia coli ProRS, a dimer of relative molecular mass 127,402, which is homologous to both ThrRS and SerRS. These three latter aaRS share three new sequence motifs with AspRS, AsnRS, LysRS, HisRS and the beta subunit of PheRS. These three motifs (motifs 1, 2 and 3), in a search through the entire data bank, proved to be specific for this set of aaRS (referred to as class II). Class II may also contain AlaRS and GlyRS, because these sequences have a typical motif 3. Surprisingly, this partition of aaRS in two classes is found to be strongly correlated on the functional level with the acylation occurring either on the 2' OH (class I) or 3' OH (class II) of the ribose of the last nucleotide of tRNA.
氨酰 - 转移RNA合成酶（aaRS）在一个高度特异性的两步反应中催化氨基酸与其对应的转移RNA分子的连接。这些蛋白质在大小和寡聚状态上差异很大，并且序列同源性有限。在已知的18种aaRS中，只有9种被称为I类合成酶（谷氨酰胺合成酶、酪氨酸合成酶、甲硫氨酸合成酶、谷氨酸合成酶、精氨酸合成酶、缬氨酸合成酶、异亮氨酸合成酶、亮氨酸合成酶、色氨酸合成酶），显示出两个短的共有序列（“HIGH”和“KMSKS”），正如在三个晶体结构中观察到的那样，这表明存在一个结合ATP的结构域（罗斯曼折叠）。我们在此报告大肠杆菌脯氨酸合成酶（ProRS）的序列，它是相对分子质量为127,402的二聚体，与苏氨酸合成酶和丝氨酸合成酶同源。后三种aaRS与天冬氨酸合成酶、天冬酰胺合成酶、赖氨酸合成酶、组氨酸合成酶以及苯丙氨酸合成酶的β亚基共享三个新的序列基序。在对整个数据库的搜索中，这三个基序（基序1、2和3）被证明是这组aaRS（称为II类）所特有的。II类可能还包含丙氨酸合成酶和甘氨酸合成酶，因为这些序列具有典型的基序3。令人惊讶的是，发现aaRS在这两类中的这种划分在功能水平上与tRNA最后一个核苷酸核糖的2' - OH（I类）或3' - OH（II类）上发生的酰化密切相关。
