Department of Molecular and Cellular Biology Laboratory, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Misuho-cho, Mizuho-ku, Nagoya, Aichi, 467-8601, Japan.
Transgenic Res. 2010 Oct;19(5):903-13. doi: 10.1007/s11248-010-9360-2. Epub 2010 Jan 20.
Previous attempts to express the human immunodeficiency virus 1 (HIV-1) Tat (trans-activator of transcription) protein in plants resulted in a number of physiological abnormalities, such as stunted growth and absence of seed formation, that could not be explained. In the study reported here, we expressed Tat in tomato and observed phenotypic abnormalities, including stunted growth, absence of root formation, chlorosis, and plant death, as a result of reduced cytokinin levels. These reduced levels were ascribed to a differentially expressed CKO35 in Tat-bombarded tomato. Of the two CKO isoforms that are naturally expressed in tomato, CKO43 and CKO37, only the expression of CKO37 was affected by Tat. Our analysis of the Tat confirmed that the Arg-rich and RGD motifs of Tat have functional relevance in tomato and that independent mutations at these motifs caused inhibition of the differentially expressed CKO isoform and the extracellular secretion of the Tat protein, respectively, in our Tat-bombarded tomato samples.
先前在植物中表达人类免疫缺陷病毒 1（HIV-1）Tat（转录激活蛋白）的尝试导致了许多无法解释的生理异常，如生长迟缓，无种子形成。在本研究中，我们在番茄中表达 Tat，并观察到表型异常，包括生长迟缓、无根形成、黄化和植物死亡，这是由于细胞分裂素水平降低所致。这些降低的水平归因于 Tat 轰击的番茄中差异表达的 CKO35。在天然表达于番茄中的两个 CKO 同工型中，只有 CKO37 的表达受到 Tat 的影响。我们对 Tat 的分析证实，富含精氨酸和 RGD 基序的 Tat 在番茄中具有功能相关性，并且这些基序的独立突变分别导致差异表达的 CKO 同工型的抑制和 Tat 蛋白的细胞外分泌，在我们的 Tat 轰击番茄样本中。
