Scippa G S, Griffiths A, Chiatante D, Bray E A
Department of Botany and Plant Sciences, University of California, Riverside, USA.
Planta. 2000 Jul;211(2):173-81. doi: 10.1007/s004250000278.
Water deficit has a significant impact on patterns of gene expression. Based on the deduced amino acid sequence, it has been proposed that the drought and abscisic acid-induced gene (his1-s) of tomato (Lycopersicon esculentum Mill.) encodes an H1 histone variant. To study the role of H1-S it is important to understand the expression characteristics of the protein. To identify the his1-s product in vivo the his1-s cDNA was fused to a (His)6 tag and overexpressed in Escherichia coli. The H1-S fusion protein was used to generate an antibody that recognized a protein with an apparent molecular weight of 31 kDa that accumulates in response to water deficit in the whole plant and detached leaves. A time course of his1-s expression showed that protein accumulation is delayed compared to the mRNA accumulation in both the whole plant and detached leaves. Cellular fractionation, immunofluorescence and H1-S::beta-glucuronidase fusion analyses in transgenic tissues were used to determine the cellular localization of H1-S. The results showed that H1-S accumulates in nuclei and is associated with chromatin of wilted tomato leaves. The drought- and abscisic acid-induced gene his1-s encodes a linker-histone subtype specifically accumulated in the nuclei and chromatin of tomato leaves subjected to water-deficit conditions. Although the molecular mechanism of H1-S function is still unclear, the expression characteristics of H1-S are consistent with a potential role of this protein in the regulation of gene expression in response to water deficit.
水分亏缺对基因表达模式有显著影响。基于推导的氨基酸序列，有人提出番茄（Lycopersicon esculentum Mill.）的干旱和脱落酸诱导基因（his1-s）编码一种H1组蛋白变体。为了研究H1-S的作用，了解该蛋白的表达特征很重要。为了在体内鉴定his1-s产物，将his1-s cDNA与一个（His）6标签融合，并在大肠杆菌中过表达。利用H1-S融合蛋白产生了一种抗体，该抗体识别一种表观分子量为31 kDa的蛋白，该蛋白在整株植物和离体叶片中因水分亏缺而积累。his1-s表达的时间进程表明，与整株植物和离体叶片中的mRNA积累相比，蛋白积累有所延迟。利用转基因组织中的细胞分级分离、免疫荧光和H1-S::β-葡萄糖醛酸酶融合分析来确定H1-S的细胞定位。结果表明，H1-S在细胞核中积累，并与萎蔫番茄叶片的染色质相关。干旱和脱落酸诱导基因his1-s编码一种连接组蛋白亚型，其特异性积累在水分亏缺条件下的番茄叶片细胞核和染色质中。虽然H1-S功能的分子机制仍不清楚，但H1-S的表达特征与该蛋白在响应水分亏缺时调节基因表达的潜在作用一致。
