Arginine kinase evolved twice: evidence that echinoderm arginine kinase originated from creatine kinase.
Arginine kinase evolved twice: evidence that echinoderm arginine kinase originated from creatine kinase.
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DOI：
10.1042/bj3400671
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发表时间：
1999-06
期刊：
影响因子：
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通讯作者：
T. Suzuki;M. Kamidochi;N. Inoue;H. Kawamichi;Y. Yazawa;T. Furukohri;W. Ellington
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文献类型：
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作者：
T. Suzuki;M. Kamidochi;N. Inoue;H. Kawamichi;Y. Yazawa;T. Furukohri;W. Ellington
从海参（Stichopus Stichopus）纵肌中分离得到精氨酸激酶（AK）。与软体动物和节肢动物的单体40 kDa AK不同，但与脊椎动物肌酸激酶（CK）的细胞质同工酶一样，海参酶是二聚体。为了探索二聚体AK的进化起源，我们测定了其cDNA衍生的370个残基的氨基酸序列。序列与属于磷酸原激酶家族的其他酶的序列的比较表明，海参AK的整个氨基酸序列显然比所有其他AK更类似于脊椎动物CK。系统发育树也强烈表明，海参AK已从CK。这些结果支持这样的结论，AK进化至少两次在磷酸原激酶的进化过程中：第一次在磷酸原激酶进化的早期阶段（其后代是软体动物和节肢动物AK），其次从CK后来在后生动物进化。胍基特异性（GS）区域周围氨基酸序列的比较（其是磷酸原激酶家族中胍底物识别位点的可能候选者）与其它磷酸原激酶的比较表明，海参酶的GS区是AK型的：在柔性环区域中的五个氨基酸缺失可能有助于在活性位点中容纳较大的胍底物。在海参AK的AK型缺失的存在下，即使它似乎是酶的最直接的祖先可能是CK，强烈表明GS区域具有底物特异性的作用。海参AK和推测其他棘皮动物AK似乎是从CK基因进化而来的; GS区域的序列可能已经通过外显子改组被AK型取代。海参AK基因GS区附近的内含子的存在支持这一假设。
Arginine kinase (AK) was isolated from the longitudinal muscle of the sea cucumber Stichopus japonicus. Unlike the monomeric 40 kDa AKs from molluscs and arthropods, but like the cytoplasmic isoenzymes of vertebrate creatine kinase (CK), the Stichopus enzyme was dimeric. To explore the evolutionary origin of the dimeric AK, we determined its cDNA-derived amino acid sequence of 370 residues. A comparison of the sequence with those of other enzymes belonging to the phosphagen kinase family indicated that the entire amino acid sequence of Stichopus AK is apparently much more similar to vertebrate CKs than to all other AKs. A phylogenetic tree also strongly suggests that the Stichopus AK has evolved from CK. These results support the conclusion that AK evolved at least twice during the evolution of phosphagen kinases: first at an early stage of phosphagen kinase evolution (its descendants are molluscan and arthropod AKs) and secondly from CK later in metazoan evolution. A comparison of the amino acid sequence around the guanidino specificity (GS) region (which is a possible candidate for the guanidine substrate recognition site in the phosphagen kinase family) of the Stichopus enzyme with those of other phosphagen kinases showed that the GS region of the Stichopus enzyme was of the AK type: five amino acid deletions in the flexible loop region that might help to accommodate larger guanidine substrates in the active site. The presence of the AK-type deletions in the Stichopus AK, even though it seems that the enzyme's most immediate ancestor was probably CK, strongly suggests that the GS region has a role in substrate specificity. Stichopus AK and presumably other echinoderm AKs seem to have evolved from the CK gene; the sequence of GS region might have been replaced by the AK type via exon shuffling. The presence of an intron near the GS region in the Stichopus AK gene supports this hypothesis.