Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
Protein Sci. 2022 Feb;31(2):407-421. doi: 10.1002/pro.4232. Epub 2021 Nov 22.
Helicases are molecular motors with many activities. They use the energy from ATP hydrolysis to unwind double-stranded nucleic acids while translocating on the single-stranded DNA. In addition to unwinding, many helicases are able to remove proteins from nucleic acids. Bacteriophage T4 Dda is able to displace a variety of DNA binding proteins and streptavidin bound to biotinylated oligonucleotides. We have identified a subdomain of Dda that when deleted, results in a protein variant that has nearly wild type activity for unwinding double-stranded DNA but exhibits greatly reduced streptavidin displacement activity. Interestingly, this domain has little effect on displacement of either gp32 or BamHI bound to DNA but does affect displacement of trp repressor from DNA. With this variant, we have identified residues which enhance displacement of some proteins from DNA.
解旋酶是具有多种活性的分子马达。它们利用 ATP 水解产生的能量，在单链 DNA 上移动的同时解开双链核酸。除了解开双链之外，许多解旋酶还能够从核酸上去除蛋白质。噬菌体 T4 的 Dda 能够置换多种 DNA 结合蛋白和与生物素化寡核苷酸结合的链霉亲和素。我们已经鉴定出 Dda 的一个亚结构域，当这个亚结构域缺失时，会导致蛋白质变体几乎具有野生型解开双链 DNA 的活性，但显示出大大降低的链霉亲和素置换活性。有趣的是，这个结构域对 gp32 或 BamHI 与 DNA 的结合置换几乎没有影响，但确实会影响色氨酸阻遏物从 DNA 上的置换。利用这种变体，我们已经确定了一些增强从 DNA 上置换某些蛋白质的残基。
