Pro-phenol oxidase activating proteinase from an insect, Manduca sexta:: A bacteria-inducible protein similar to Drosophila easter
Pro-phenol oxidase activating proteinase from an insect, Manduca sexta:: A bacteria-inducible protein similar to Drosophila easter
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DOI：
10.1073/pnas.95.21.12220
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发表时间：
1998-10-13
影响因子：
11.1
通讯作者：
Kanost, MR
中科院分区：
文献类型：
--
作者：
Jiang, HB;Wang, Y;Kanost, MR
在昆虫和甲壳类动物中，酚氧化酶原(ProPO)的激活在抵御创伤和感染方面起着重要作用。原酶原被特定的蛋白水解性裂解激活。Po氧化酚类化合物产生苯二酚，这可能有助于杀死病原体，也可以用来合成黑色素来封闭伤口和包裹寄生虫。我们从烟草天牛Manduca sexta中分离到一种激活ProPO的丝氨酸蛋白酶，并克隆了它的cDNA.Proo激活酶(PAP)是一种人工底物水解酶，但需要其他蛋白质因子才能激活Proo，提示Proo激活酶可能以蛋白质复合体的形式存在，其中一个组分是PAP，PAP(44 KDa)是由两条二硫键连接的多肽链(31 kDa和13 kDa)组成的，通过使用PCR产生的基于31 kDa催化区氨基端氨基酸序列的探针，从血细胞文库中克隆了PAP的cDNA。PAP属于节肢动物丝氨酸蛋白酶家族，含有一个羧基末端的蛋白水解酶结构域和一个氨基末端的“夹”结构域。该家族中与PAP序列最相似的成员是果蝇的复活节基因产物，PAP在幼虫血细胞和脂肪体中的表达水平较低，但在昆虫体内的表达水平较高。序列数据和H-3-二异丙基氟磷酸标记结果表明，同样的PAP存在于血淋巴和角质层中。
Activation of pro-phenol oxidase (proPO) in insects and crustaceans is important in defense against wounding and infection. The proPO zymogen is activated by a specific proteolytic cleavage. PO oxidizes phenolic compounds to produce quinones, which may help to kill pathogens and can also be used for synthesis of melanin to seal wounds and encapsulate parasites. We have isolated from the tobacco hornworm, Manduca sexta, a serine proteinase that activates proPO, and have cloned its cDNA The isolated proPO activating proteinase (PAP) hydrolyzed artificial substrates but required other protein factors for proPO activation, suggesting that proPO-activating enzyme may exist as a protein complex, one component of which is PAP, PAP (44 kDa) is composed of two disulfide-linked polypeptide chains (31 kDa and 13 kDa), A cDNA for PAP was isolated from a hemocyte library, by using a PCR-generated probe based on the aminoterminal amino acid sequence of the 31-kDa catalytic domain. PAP belongs to a family of arthropod serine proteinases containing a carboxyl-terminal proteinase domain and an amino-terminal "clip" domain. The member of this family most similar in sequence to PAP is the product of the easter gene from Drosophila melanogaster, PAP mRNA was present at a low level in larval hemocytes and fat body, but became much more abundant in fat body after insects were injected with Escherichia coli, Sequence data and H-3-diisopropyl fluorphosphate labeling results suggest that the same PAP exists in hemolymph and cuticle.