Evolution of trypsinogen activation peptides
Evolution of trypsinogen activation peptides
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DOI：
10.1093/molbev/msg183
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发表时间：
2003-11-01
影响因子：
10.7
通讯作者：
Sahin-Tóth, M
中科院分区：
文献类型：
--
作者：
Chen, JM;Kukor, Z;Sahin-Tóth, M
哺乳动物胰酶原激活肽含有一个高度保守的四天冬氨酸序列(D19-D20-D21-D22)，位于K23-I24剪切肽键之前，作为激活过程的第一步，K23-I24剪切肽键被水解。在这里，我们通过结合疾病相关突变的功能特征和比较基因组分析来研究胰酶原激活肽的进化和功能。首次在重组人阳离子胰蛋白酶原的背景下，同时分析了三个慢性胰腺炎相关激活肽突变体(新的D19A和先前报道的D22G和K23R)的激活特性。在所有三个突变体中都观察到阳离子胰蛋白酶原的自激活显著增加，其中D22G和K23R表现出最显著的增加。生理激活剂肠肽酶对D19A突变体的激活作用正常，对D22G突变体的激活作用很弱，对K23R突变体的激活作用较弱。结合生化和结构数据，结合全面的序列比较，表明哺乳动物胰酶原激活肽中的四天冬氨酸序列不仅在十二指肠中具有最佳的肠肽酶识别能力，而且在胰腺内也能有效地抑制胰蛋白酶原的自我激活。此外，在活化肽的PI位用赖氨酸代替精氨酸也对胰蛋白酶原的自活化有有利的影响。最后，胰酶原激活肽关键残基的固定取代可能暗示了与消化无关的新功能的进化，就像在冷适应鱼类的第三类胰酶原中发现的那样。
The activation peptide of mammalian trypsinogens contains a highly conserved tetra-aspartate sequence (D19-D20-D21-D22) preceding the K23-I24 scissile peptide bond, which is hydrolyzed as the first step in the activation process. Here, we examined the evolution and function of trypsinogen activation peptides through integrating functional characterization of disease-associated mutations with comparative genomic analysis. Activation properties of three chronic pancreatitis-associated activation peptide mutants (the novel D19A and the previously reported D22G and K23R) were simultaneously analyzed, for the first time, in the context of recombinant human cationic trypsinogen. A dramatic increase in autoactivation of cationic trypsinogen was observed in all three mutants, with D22G and K23R exhibiting the most marked increases. The physiological activator enteropeptidase activated the D19A mutant normally, activated the D22G mutant very poorly, and stimulated activation of the K23R mutant. The biochemical and structural data, taken together with a comprehensive sequence comparison, indicates that the tetra-aspartate sequence in mammalian trypsinogen activation peptides has evolved not only for optimal enteropeptidase recognition in the duodenum but also for efficient inhibition of trypsinogen autoactivation within the pancreas. Moreover, the use of lysine instead of arginine at the PI position of activation peptides also has an advantageous effect against trypsinogen autoactivation. Finally, fixed substitutions in the key residues of the trypsinogen activation peptide may suggest the evolution of new functions unrelated to digestion, as found in the group III trypsinogens of cold-adapted fishes.