Calmodulin-like protein AtCML3 mediates dimerization of peroxisomal processing protease AtDEG15 and contributes to normal peroxisome metabolism.
Calmodulin-like protein AtCML3 mediates dimerization of peroxisomal processing protease AtDEG15 and contributes to normal peroxisome metabolism.
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DOI：
10.1007/s11103-013-0112-6
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发表时间：
2013-12
影响因子：
5.1
通讯作者：
Gietl, Christine
中科院分区：
文献类型：
--
作者：
Dolze, Esther;Chigri, Fatima;Hoewing, Timo;Hierl, Georg;Isono, Erika;Vothknecht, Ute C.;Gietl, Christine
基质酶被导入过氧化物酶体和乙氧基酶体，这是参与脂质动员的过氧化物酶体的一个亚类。两个过氧化物酶体靶向信号（PTS）， c端PTS1和n端PTS2，介导蛋白质转运到细胞器。PTS2在进口后的加工在高等真核生物中是保守的，在西瓜中，glyoxysomal processing protease （GPP）被证明可以催化PTS2的加工。GPP及其同源物拟南芥过氧化物酶体DEG蛋白酶（AtDEG15）属于DEG /HtrA家族的atp非依赖性丝氨酸蛋白酶，以大肠杆菌DegP为原型。GPP以单体和二聚体形式存在。它们的平衡在Ca2+去除后向单体转移，在Ca2+添加时向二聚体转移，这伴随着底物特异性的变化，从一般蛋白酶（单体）到PTS2（二聚体）的特定切割。我们描述了Ca2+/钙调蛋白（CaM）介导的AtDEG15二聚化。酵母2和3杂交分析表明，二聚化是由cam样蛋白AtCML3介导的。AtCML3的结合发生在AtDEG15的前25个n端氨基酸中，该结构域包含预测的cam结合基序。植物中AtDEG15缺失结构的生化分析支持cam结合结构域对PTS2处理的要求。系统发育分析表明，cam结合位点在高等植物（双子叶植物、单子叶植物）的过氧化物酶体加工蛋白酶中是保守的，但在动物或细胞黏菌的同源物中不存在。尽管PTS2加工活动正常，但atcml3突变体表现出2,4- db敏感性降低，这是先前报道的atdeg15突变体的表型，表明类似的过氧化物酶体代谢受损。本文的在线版本（doi:10.1007/s11103-013-0112-6）包含补充资料，仅供授权用户使用。
Matrix enzymes are imported into peroxisomes and glyoxysomes, a subclass of peroxisomes involved in lipid mobilization. Two peroxisomal targeting signals (PTS), the C-terminal PTS1 and the N-terminal PTS2, mediate the translocation of proteins into the organelle. PTS2 processing upon import is conserved in higher eukaryotes, and in watermelon the glyoxysomal processing protease (GPP) was shown to catalyse PTS2 processing. GPP and its ortholog, the peroxisomal DEG protease from Arabidopsis thaliana (AtDEG15), belong to the Deg/HtrA family of ATP-independent serine proteases with Escherichia coli DegP as their prototype. GPP existes in monomeric and dimeric forms. Their equilibrium is shifted towards the monomer upon Ca2+-removal and towards the dimer upon Ca2+-addition, which is accompanied by a change in substrate specificity from a general protease (monomer) to the specific cleavage of the PTS2 (dimer). We describe the Ca2+/calmodulin (CaM) mediated dimerization of AtDEG15. Dimerization is mediated by the CaM-like protein AtCML3 as shown by yeast two and three hybrid analyses. The binding of AtCML3 occurs within the first 25 N-terminal amino acids of AtDEG15, a domain containing a predicted CaM-binding motif. Biochemical analysis of AtDEG15 deletion constructs in planta support the requirement of the CaM-binding domain for PTS2 processing. Phylogenetic analyses indicate that the CaM-binding site is conserved in peroxisomal processing proteases of higher plants (dicots, monocots) but not present in orthologs of animals or cellular slime molds. Despite normal PTS2 processing activity, an atcml3 mutant exhibited reduced 2,4-DB sensitivity, a phenotype previously reported for the atdeg15 mutant, indicating similarly impaired peroxisome metabolism. The online version of this article (doi:10.1007/s11103-013-0112-6) contains supplementary material, which is available to authorized users.
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影响因子：
12.3
作者：
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影响因子：
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