Eini Omid, Behjatnia S A Akbar, Dogra Satish, Dry Ian B, Randles John W, Rezaian M Ali
School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, SA 5064, Australia.
J Gen Virol. 2009 Jan;90(Pt 1):253-60. doi: 10.1099/vir.0.002980-0.
DNA beta is a circular single-stranded satellite DNA associated with certain monopartite begomoviruses (family Geminiviridae) which causes economically important diseases such as cotton leaf curl disease. DNA beta contains a single gene, betaC1, which encodes a pathogenicity protein responsible for symptom production. Transient expression studies in Nicotiana tabacum using the beta-glucuronidase reporter gene driven by a betaC1 promoter-deletion series of the DNA beta associated with cotton leaf curl Multan virus identified a 68 nt region (between -139 and -207) which is important for betaC1 transcription. This 68 nt region contains a G-box (CACGTG) located 143 nt upstream of the betaC1 start codon. Mutation of the G-box resulted in a significant reduction in betaC1 promoter activity and DNA beta replication efficiency. In addition, the G-box motif was found to bind specifically to a protein(s) in nuclear extracts prepared from tobacco leaf tissues. Our results indicate that interaction of the G-box motif with host nuclear factors is important for efficient gene expression and replication of DNA beta.
DNAβ是一种环状单链卫星DNA，与某些单组分双生病毒（双生病毒科）相关，这些双生病毒会引发如棉花卷叶病等具有重要经济影响的疾病。DNAβ含有一个单一基因βC1，该基因编码一种负责症状产生的致病蛋白。利用由与棉花卷叶木尔坦病毒相关的DNAβ的βC1启动子缺失系列驱动的β-葡萄糖醛酸酶报告基因，在烟草中进行的瞬时表达研究确定了一个68 nt的区域（在-139至-207之间），该区域对βC1转录很重要。这个68 nt的区域包含一个位于βC1起始密码子上游143 nt处的G-box（CACGTG）。G-box的突变导致βC1启动子活性和DNAβ复制效率显著降低。此外，发现G-box基序能与从烟草叶片组织制备的核提取物中的一种或多种蛋白质特异性结合。我们的结果表明，G-box基序与宿主核因子的相互作用对于DNAβ的有效基因表达和复制很重要。
