Römer Patrick, Strauss Tina, Hahn Simone, Scholze Heidi, Morbitzer Robert, Grau Jan, Bonas Ulla, Lahaye Thomas
Institute of Biology, Department of Genetics , Martin Luther University Halle-Wittenberg, 06120 Halle , Germany.
Plant Physiol. 2009 Aug;150(4):1697-712. doi: 10.1104/pp.109.139931. Epub 2009 May 15.
The pepper (Capsicum annuum) bacterial spot (Bs) resistance gene Bs3 and its allelic variant Bs3-E mediate recognition of the Xanthomonas campestris pv vesicatoria type III effector protein AvrBs3 and its deletion derivative AvrBs3Deltarep16. Recognition specificity resides in the Bs3 and Bs3-E promoters and is determined by a defined promoter region, the UPA (for up-regulated by AvrBs3) box. Using site-directed mutagenesis, we defined the exact boundaries of the UPA(AvrBs3) box of the Bs3 promoter and the UPA(AvrBs3Deltarep16) box of the Bs3-E promoter and show that both boxes overlap by at least 11 nucleotides. Despite partial sequence identity, the UPA(AvrBs3) box and the UPA(AvrBs3Deltarep16) box were bound specifically by the corresponding AvrBs3 and AvrBs3Deltarep16 proteins, respectively, suggesting that selective promoter binding of AvrBs3-like proteins is the basis for promoter activation specificity. We also demonstrate that the UPA(AvrBs3) box retains its functionality at different positions within the pepper Bs3 promoter and confers AvrBs3 inducibility in a novel promoter context. Notably, the transfer of the UPA(AvrBs3) box to different promoter locations is always correlated with a new transcriptional start site. The analysis of naturally occurring Bs3 alleles revealed many pepper accessions that encode a nonfunctional Bs3 variant. These accessions showed no apparent abnormalities, supporting the supposition that Bs3 functions only in disease resistance and not in other developmental or physiological processes.
辣椒（Capsicum annuum）抗细菌性斑点病（Bs）基因Bs3及其等位变体Bs3-E介导对野油菜黄单胞菌辣椒斑点病菌III型效应蛋白AvrBs3及其缺失衍生物AvrBs3Deltarep16的识别。识别特异性存在于Bs3和Bs3-E启动子中，并由一个特定的启动子区域——UPA（受AvrBs3上调）框决定。通过定点诱变，我们确定了Bs3启动子的UPA（AvrBs3）框和Bs3-E启动子的UPA（AvrBs3Deltarep16）框的确切边界，并表明这两个框至少有11个核苷酸重叠。尽管部分序列相同，但UPA（AvrBs3）框和UPA（AvrBs3Deltarep16）框分别与相应的AvrBs3和AvrBs3Deltarep16蛋白特异性结合，这表明AvrBs3样蛋白的选择性启动子结合是启动子激活特异性的基础。我们还证明，UPA（AvrBs3）框在辣椒Bs3启动子内的不同位置保留其功能，并在新的启动子环境中赋予AvrBs3诱导性。值得注意的是，UPA（AvrBs3）框转移到不同的启动子位置总是与一个新的转录起始位点相关。对天然存在的Bs3等位基因的分析揭示了许多编码无功能Bs3变体的辣椒种质。这些种质没有表现出明显的异常，支持了Bs3仅在抗病性中起作用而不在其他发育或生理过程中起作用的假设。
