Wall-associated kinase WAK1 interacts with cell wall pectins in a calcium-induced conformation
Wall-associated kinase WAK1 interacts with cell wall pectins in a calcium-induced conformation
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DOI：
10.1093/pcp/pci026
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发表时间：
2005-02-01
影响因子：
4.9
通讯作者：
Messiaen, J
中科院分区：
文献类型：
--
作者：
Decreux, A;Messiaen, J
细胞壁相关激酶1（WAK1）是一种跨膜蛋白，含有细胞质Ser/Thr激酶结构域和与植物细胞壁的果胶部分接触的细胞外结构域。为了进一步表征WAK 1与果胶的相互作用，克隆了对应于来自拟南芥的WAK 1胞外结构域的氨基酸67 - 254的564 bp DNA序列，并在酵母中表达为可溶性重组肽。用酶联免疫吸附试验（ELISA），我们证明WAK（67 - 254）肽能与多聚半乳糖醛酸（PGA）、寡聚半乳糖醛酸、从A. thaliana细胞壁和结构上相关的藻酸盐。我们的研究结果表明，离子和空间相互作用都需要匹配相对线性的果胶骨架。WAK（67 - 254）与PGA、低聚半乳糖醛酸内酯和藻酸盐的结合仅在钙存在下和在促进寡聚物和聚合物之间形成钙桥（也称为"卵盒"）的离子条件下发生。抑制钙桥形成的条件（EDTA处理、钙替代、高NaCl浓度、果胶的解聚和甲酯化）也抑制WAK（67 - 254）与钙诱导的卵盒的结合。WAK（67 - 254）和细胞壁果胶之间的这种非共价键的相关性进行了讨论，在细胞伸长，细胞分化和宿主-病原体相互作用。
Wall-associated kinase 1 (WAK1) is a transmembrane protein containing a cytoplasmic Ser/Thr kinase domain and an extracellular domain in contact with the pectin fraction of the plant cell walls. In order to characterize further the interaction of WAK1 with pectin, a 564 bp DNA sequence corresponding to amino acids 67-254 of the extracellular domain of WAK1 from Arabidopsis thaliana was cloned and expressed as a soluble recombinant peptide in yeast. Using enzyme-linked immunosorbent assays (ELISA), we show that peptide WAK(67-254) binds to polygalacturonic acid (PGA), oligogalacturonides, pectins extracted from A. thaliana cell walls and to structurally related alginates. Our results suggest that both ionic and steric interactions are required to match the relatively linear pectin backbone. Binding of WAK(67-254) to PGA, olligogallacturonides and alginates occurred only in the presence of calcium and in ionic conditions promoting the formation of calcium bridges between oligo-and polymers (also known as 'egg-boxes'). The conditions inhibiting the formation of calcium bridges (EDTA treatment, calcium substitution, high NaCl concentrations, depolymerization and methylesterification of pectins) also inhibited the binding of WAK(67-254) to calcium-induced egg-boxes. The relevance of this non-covalent link between WAK(67-254) and cell wall pectins is discussed in terms of cell elongation, cell differentiation and host-pathogen interactions.