Giam C Z, Nerenberg M, Khoury G, Jay G
Proc Natl Acad Sci U S A. 1986 Oct;83(19):7192-6. doi: 10.1073/pnas.83.19.7192.
Human T-cell leukemia virus type I (HTLV-I), a virus associated with adult T-cell leukemia, contains a long open reading frame (LOR) in the 3' end of its genome between the env region and the 3' long terminal repeat (LTR). This open reading frame encodes a 40-kDa protein (designated p40x) that has been implicated as a positive control element for transcription from the HTLV-I LTR in a phenomenon known as trans-activation. We now report the expression of the complete p40x coding sequence as a 40-kDa protein in Escherichia coli. The p40x protein produced in bacteria is shown, using the protoplast fusion technique, to possess biological activity by its ability to trans-activate a HTLV-I LTR-chloramphenicol acetyltransferase plasmid that is stably integrated into the genome of mouse L cells. This stimulatory activity could be detected within 2 hr after fusion, suggesting the possibility of a direct role for p40x in trans-activation of the HTLV-I LTR. The production of p40x in large quantities in E. coli, together with the rapid protoplast fusion assay for its biological activity, should facilitate the analysis of p40x mutants and the elucidation of the molecular mechanism of trans-activation.
人类I型T细胞白血病病毒（HTLV-I）是一种与成人T细胞白血病相关的病毒，在其基因组的env区域和3'长末端重复序列（LTR）之间的3'端含有一个长开放阅读框（LOR）。这个开放阅读框编码一种40 kDa的蛋白质（命名为p40x），在一种被称为反式激活的现象中，它被认为是HTLV-I LTR转录的正调控元件。我们现在报道完整的p40x编码序列在大肠杆菌中表达为一种40 kDa的蛋白质。利用原生质体融合技术显示，细菌中产生的p40x蛋白通过其反式激活稳定整合到小鼠L细胞基因组中的HTLV-I LTR-氯霉素乙酰转移酶质粒的能力而具有生物学活性。这种刺激活性在融合后2小时内即可检测到，这表明p40x在HTLV-I LTR反式激活中可能直接起作用。在大肠杆菌中大量生产p40x，以及对其生物学活性进行快速原生质体融合测定，应有助于分析p40x突变体并阐明反式激活的分子机制。
