Atanassov I, Russinova E, Antonov L, Atanassov A
Institute of Genetic Engineering, Kostinbrod, Bulgaria.
Plant Mol Biol. 1998 Dec;38(6):1169-78. doi: 10.1023/a:1006074508779.
Two cDNA clones, specifically expressed in Nicotiana sylvestris anthers during uninucleate microspore development, were isolated using a subtractive hybridization approach. Sequence analysis showed that one of them, NSCHSLK, displayed a high level of similarity to several anther-specific chalcone synthase-like (CHSLK) proteins and an ORF from chromosome I of Arabidopsis thaliana. A lower, but significant, similarity to chalcone synthases and closely related enzymes (CHSRE) was also detected. The structure of the nschslk gene was found to be typical of the chalcone (chs)/stilbene (sts) synthase family. Expression of NSCHSLK mRNA was confined to microspores and tapetal cells. UV-irradiation or infection with Phytophthora parasitica var. nicotianae of transgenic Nicotiana benthamiana plants carrying a chimeric nschslk/GUS gene indicated that the nschslk promoter exhibits the same anther-specific, developmentally regulated expression pattern. Comparison of CHSRE and CHSLK polypeptide sequences revealed some important similarities and differences between the two groups. The data presented in this study, suggest that the anther-specific chslk genes represent a separate sub-family of plant polyketide synthases related to chs/sts in terms of gene structure, polypeptide sequence and the possible catalytic mechanism, but differing in substrate/product specificity. The putative role of CHSLK enzymes in anther development and particularly in exine synthesis is discussed.
利用消减杂交方法分离出了两个在单核小孢子发育过程中于烟草花药中特异性表达的cDNA克隆。序列分析表明，其中一个名为NSCHSLK的克隆与几种花药特异性查尔酮合酶样（CHSLK）蛋白以及拟南芥第一条染色体上的一个开放阅读框具有高度相似性。同时还检测到与查尔酮合酶及密切相关酶（CHSRE）存在较低但显著的相似性。发现nschslk基因的结构是查尔酮（chs）/芪（sts）合酶家族的典型结构。NSCHSLK mRNA的表达局限于小孢子和绒毡层细胞。对携带嵌合nschslk/GUS基因的转基因本氏烟草植株进行紫外线照射或接种烟草疫霉变种表明，nschslk启动子呈现出相同的花药特异性、发育调控的表达模式。CHSRE和CHSLK多肽序列的比较揭示了两组之间一些重要的异同点。本研究提供的数据表明，花药特异性chslk基因代表了植物聚酮合酶的一个独立亚家族，在基因结构、多肽序列和可能的催化机制方面与chs/sts相关，但在底物/产物特异性方面有所不同。文中还讨论了CHSLK酶在花药发育尤其是花粉外壁合成中的假定作用。
