Abstract：
The protein HSF-1 is the controlling transcription factor of the heat-shock response (HSR). Its binding to the heat-shock elements (HSEs) induces the strong upregulation of conserved heat-shock proteins, including Hsp70s, Hsp40s and small HSPs. Next to these commonly known HSPs, more than 4000 other HSEs are found in the promoter regions of C. elegans genes. In microarray experiments, few of the HSE-containing genes are specifically upregulated during the heat-shock response. Most of the 4000 HSE-containing genes instead are unaffected by elevated temperatures and coexpress with genes unrelated to the HSR. This is also the case for several genes related to the HSP chaperone system, like dnj-12, dnj-13, and hsp-1. Interestingly, several promoters of the dedicated HSR-genes, like F44E5.4p, hsp-16.48p or hsp-16.2p, contain extended HSEs in their promoter region, composed of four or five HSE-elements instead of the common trimeric HSEs. We here aim at understanding how HSF-1 interacts with the different promoter regions. To this end we purify the nematode HSF-1 DBD and investigate the interaction with DNA sequences containing these regions. EMSA assays suggest that the HSF-1 DBD interacts with most of these HSE-containing dsDNAs, but with different characteristics. We employ sedimentation analytical ultracentrifugation (SV-AUC) to determine stoichiometry, affinity, and cooperativity of HSF-1 DBD binding to these HSEs. Interestingly, most HSEs show cooperative binding of the HSF-1 DBD with up to five DBDs being bound. In most cases binding to the HSEs of inducible promoters is stronger, even though the consensus scores are not always higher. The observed high affinity of HSF-1 DBD to the non-inducible HSEs of dnj-12, suggests that constitutive expression may be supported from some promoter regions, a fact that is evident for this transcription factor, that is essential also under non-stress conditions.
摘要：
HSF-1蛋白是热休克反应（HSR）的控制转录因子。它与热休克元件（HSE）的结合会诱导保守的热休克蛋白的强烈上调，包括HSP70s,Hsp40和小型HSP。除了这些众所周知的HSP，在C.elegans基因的启动子区域中发现了超过4000种其他HSE。在微阵列实验中,在热休克反应期间，很少有含有HSE的基因被特异性上调。相反，大多数4000个含HSE的基因不受高温的影响，并与与HSR无关的基因共表达。与HSP伴侣系统相关的几个基因也是如此，比如dnj-12、dnj-13和hsp-1。有趣的是,专用HSR基因的几个启动子，像F44E5.4p，hsp-16.48p或hsp-16.2p，在其启动子区域含有延伸的HSE，由四个或五个HSE元素组成，而不是共同的三聚体HSE。我们在此旨在理解HSF-1如何与不同启动子区域相互作用。为此，我们纯化了线虫HSF-1DBD，并研究了与包含这些区域的DNA序列的相互作用。EMSA试验表明，HSF-1DBD与大多数含有HSE的dsDNA相互作用，但有不同的特点。我们采用沉降分析超速离心（SV-AUC）来确定化学计量，亲和力,以及HSF-1DBD与这些HSE结合的协同性。有趣的是,大多数HSE显示HSF-1DBD的协同结合，最多结合五个DBD。在大多数情况下，与诱导型启动子的HSE结合更强，即使共识得分并不总是更高。观察到的HSF-1DBD对dnj-12的非诱导型HSE的高亲和力表明，一些启动子区域可能支持组成型表达，对于这种转录因子来说，这是显而易见的事实，这在非压力条件下也是必不可少的。
