York William S, Qin Qiang, Rose Jocelyn K C
Department of Biochemistry and Molecular Biology, Complex Carbohydrate Research Center, University of Georgia, 220 Riverbend Road, Athens, GA 30602-4712, USA.
Biochim Biophys Acta. 2004 Feb 12;1696(2):223-33. doi: 10.1016/j.bbapap.2003.07.003.
Both plants and filamentous phytopathogens secrete proteins that inhibit endo-beta-glucanases. The first endo-beta-glucanase inhibitor proteins to be discovered are XEGIP, a tomato protein that inhibits fungal xyloglucan-specific endo-beta-1,4-glucanases, and GIP1, an oomycete protein that inhibits endo-beta-1,3-glucanases produced by the plant host. These inhibitor proteins act by forming high-affinity complexes with their endoglucanase ligands. A family of XEGIP-like proteins has been identified. At least one member of this family (extracellular dermal glycoprotein, EDGP) has been shown to have endoglucanase-inhibitor activity, while other members have sequence similarity to a xylanase inhibitor from wheat (TAXI-1). The oomycete inhibitor GIP1 is a catalytically inactive serine protease homolog (SPH) whose structure is unrelated to XEGIP. Both types of inhibitor proteins are likely to affect the interactions of plants with filamentous phytopathogens, and a basic model describing their roles in pathogenesis is proposed.
植物和丝状植物病原体都会分泌抑制内切β-葡聚糖酶的蛋白质。最早发现的内切β-葡聚糖酶抑制蛋白是XEGIP，一种抑制真菌木葡聚糖特异性内切β-1,4-葡聚糖酶的番茄蛋白，以及GIP1，一种抑制植物宿主产生的内切β-1,3-葡聚糖酶的卵菌蛋白。这些抑制蛋白通过与其内切葡聚糖酶配体形成高亲和力复合物来发挥作用。已鉴定出一个XEGIP样蛋白家族。该家族的至少一个成员（细胞外真皮糖蛋白，EDGP）已被证明具有内切葡聚糖酶抑制活性，而其他成员与小麦的木聚糖酶抑制剂（TAXI-1）具有序列相似性。卵菌抑制剂GIP1是一种催化无活性的丝氨酸蛋白酶同源物（SPH），其结构与XEGIP无关。这两种类型的抑制蛋白都可能影响植物与丝状植物病原体的相互作用，并提出了一个描述它们在发病机制中作用的基本模型。
