Yamauchi Daisuke, Zentella Rodolfo, Ho Tuan-hua David
Department of Biological Sciences, Tokyo Metropolitan University, Minami-ohsawa 1-1, Hachioji, Tokyo 192-0397, Japan.
Planta. 2002 Jun;215(2):319-26. doi: 10.1007/s00425-002-0740-6. Epub 2002 Mar 9.
Abscisic acid (ABA) induces the expression of a gene encoding a protein kinase, PKABA1, in wheat ( Triticum aestivum L.). Transient expression of the cDNA encoding this kinase suppresses the gibberellin (GA)-induced expression of alpha-amylase genes in barley ( Hordeum vulgare L.) aleurone layers. We have cloned the cDNA and genomic sequences for the barley PKABA1 (HvPKABA1) to further study its role in regulating the GA-inducible gene expression in barley seeds. The amino acid sequence deduced from the cDNA shows 97% identity with that of wheat PKABA1. RNA blot analysis indicated that ABA induced, but GA suppressed, the expression of HvPKABA1 in barley seeds. Transient expression of HvPKABA1 also suppressed the GA-inducible alpha-amylase gene expression. These results suggest that HvPKABA1 is probably involved in the signal transduction pathway from ABA to suppress the GA-inducible gene expression. Southern blot analysis showed that HvPKABA1 is likely a single-copy gene in barley. The sequence of the genomic clone reveals that HvPKABA1 consists of eight introns, the first one being more than 6 kb long. The mapped transcription start site of this gene suggests that it may have a TATA-less promoter.
脱落酸（ABA）可诱导小麦（Triticum aestivum L.）中一个编码蛋白激酶PKABA1的基因表达。编码该激酶的cDNA的瞬时表达可抑制大麦（Hordeum vulgare L.）糊粉层中赤霉素（GA）诱导的α-淀粉酶基因的表达。我们已克隆了大麦PKABA1（HvPKABA1）的cDNA和基因组序列，以进一步研究其在调节大麦种子中GA诱导型基因表达中的作用。从cDNA推导的氨基酸序列与小麦PKABA1的氨基酸序列具有97%的同一性。RNA印迹分析表明，ABA诱导但GA抑制大麦种子中HvPKABA1的表达。HvPKABA1的瞬时表达也抑制了GA诱导的α-淀粉酶基因表达。这些结果表明，HvPKABA1可能参与了从ABA到抑制GA诱导型基因表达的信号转导途径。Southern印迹分析表明，HvPKABA1在大麦中可能是单拷贝基因。基因组克隆的序列显示，HvPKABA1由八个内含子组成，第一个内含子长度超过6 kb。该基因的转录起始位点定位表明它可能有一个无TATA框的启动子。
