Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, 4101 Sherbrooke Est, Université de Montréal, Montréal, H1X 2B2, Canada.
BMC Mol Cell Biol. 2021 May 8;22(1):27. doi: 10.1186/s12860-021-00368-4.
Dinoflagellates have a generally large number of genes but only a small percentage of these are annotated as transcription factors. Cold shock domain (CSD) containing proteins (CSPs) account for roughly 60% of these. CSDs are not prevalent in other eukaryotic lineages, perhaps suggesting a lineage-specific expansion of this type of transcription factors in dinoflagellates, but there is little experimental data to support a role for dinoflagellate CSPs as transcription factors. Here we evaluate the hypothesis that dinoflagellate CSPs can act as transcription factors by binding double-stranded DNA in a sequence dependent manner.
We find that both electrophoretic mobility shift assay (EMSA) competition experiments and selection and amplification binding (SAAB) assays indicate binding is not sequence specific for four different CSPs from two dinoflagellate species. Competition experiments indicate all four CSPs bind to RNA better than double-stranded DNA.
Dinoflagellate CSPs do not share the nucleic acid binding properties expected for them to function as bone fide transcription factors. We conclude the transcription factor complement of dinoflagellates is even smaller than previously thought suggesting that dinoflagellates have a reduced dependance on transcriptional control compared to other eukaryotes.
甲藻具有大量的基因，但只有一小部分被注释为转录因子。冷休克结构域（CSD）包含的蛋白质（CSPs）约占这些转录因子的 60%。CSD 在其他真核生物谱系中并不常见，这可能表明这种类型的转录因子在甲藻中具有谱系特异性扩张，但几乎没有实验数据支持甲藻 CSPs 作为转录因子的作用。在这里，我们评估了甲藻 CSPs 可以通过序列依赖性方式结合双链 DNA 来作为转录因子的假说。
我们发现，电泳迁移率变动分析（EMSA）竞争实验和选择和扩增结合（SAAB）实验都表明，对于来自两种甲藻的四个不同的 CSP，结合不是序列特异性的。竞争实验表明，所有四个 CSP 都比双链 DNA 更能与 RNA 结合。
甲藻 CSPs 不具有作为真正转录因子的核酸结合特性。我们得出结论，甲藻的转录因子组成甚至比以前想象的还要小，这表明与其他真核生物相比，甲藻对转录控制的依赖性更小。
