Ward E R, Payne G B, Moyer M B, Williams S C, Dincher S S, Sharkey K C, Beck J J, Taylor H T, Ahl-Goy P, Meins F, Ryals J A
CIBA-GEIGY Corporation, Agricultural Biotechnology Research Unit, Research Triangle Park, North Carolina 27709.
Plant Physiol. 1991 Jun;96(2):390-7. doi: 10.1104/pp.96.2.390.
The acidic, extracellular, glucan endo-1,3-beta-glucosidases (EC 3.2.1.39; beta-1,3-glucanases), pathogenesis-related proteins-2, -N, and -O (i.e. PR-2, PR-N, and PR-O) were purified from Nicotiana tabacum (tobacco) and their partial amino acid sequences determined. Based on these data, complementary DNA (cDNA) clones encoding the proteins were isolated. Additional cDNAs were isolated that encoded proteins approximately 90% identical with PR-2, PR-N, and PR-O. Although the proteins encoded by these cDNAs have not been identified, their deduced amino acid sequences have slightly basic or neutral calculated isoelectric points, as well as carboxy-terminal extensions. These physical characteristics are shared by the vacuolar form of beta-1,3-glucanase and other vacuolar localized analogs of PR proteins, suggesting that the unidentified proteins may be similarly localized. A preliminary evolutionary model that separates the beta-1,3-glucanase gene family from tobacco into at least five distinct subfamilies is proposed. The expression of beta-1,3-glucanase messenger RNAs (mRNAs) in response to infection by tobacco mosaic virus was examined. Messages for the acidic glucanases were induced similarly to the mRNAs for other PR proteins. However, the basic glucanase showed a different response, suggesting that different isoforms are differentially regulated by tobacco mosaic virus infection at the mRNA level.
从烟草（Nicotiana tabacum）中纯化出酸性胞外葡聚糖内切-1,3-β-葡糖苷酶（EC 3.2.1.39；β-1,3-葡聚糖酶）、病程相关蛋白-2、-N和-O（即PR-2、PR-N和PR-O），并测定了它们的部分氨基酸序列。基于这些数据，分离出了编码这些蛋白的互补DNA（cDNA）克隆。还分离出了其他cDNA，它们编码的蛋白与PR-2、PR-N和PR-O约90%相同。虽然这些cDNA编码的蛋白尚未鉴定，但它们推导的氨基酸序列具有略呈碱性或中性的计算等电点以及羧基末端延伸。这些物理特性与β-1,3-葡聚糖酶的液泡形式和PR蛋白的其他液泡定位类似物相同，表明未鉴定的蛋白可能也定位于液泡。提出了一个初步的进化模型，将烟草中的β-1,3-葡聚糖酶基因家族分为至少五个不同的亚家族。研究了β-1,3-葡聚糖酶信使核糖核酸（mRNA）对烟草花叶病毒感染的反应。酸性葡聚糖酶的信使核糖核酸与其他PR蛋白的信使核糖核酸一样被诱导。然而，碱性葡聚糖酶表现出不同的反应，这表明不同的同工型在mRNA水平上受到烟草花叶病毒感染的差异调节。
