Department of Chemistry and Biochemistry, Florida International University , 11200 SW Eighth Street, AHC4-233, Miami, Florida 33199, United States.
Anal Chem. 2014 Jan 21;86(2):1210-4. doi: 10.1021/ac403386q. Epub 2014 Jan 8.
The mammalian high mobility group protein HMGA2 contains three DNA binding motifs associated with many physiological functions including oncogenesis, obesity, stem cell youth, human height, and human intelligence. In the present paper, trapped ion mobility spectrometry-mass spectrometry (TIMS-MS) has been utilized to study the conformational dynamics of the third DNA binding motif using the "AT hook" decapeptide unit (Lys(1)-Arg(2)-Prol(3)-Arg(4)-Gly(5)-Arg(6)-Prol(7)-Arg(8)-Lys(9)-Trp(10), ATHP) as a function of the solvent state. Solvent state distributions were preserved during electrospray ion formation, and multiple IMS bands were identified for the M + 2H and for the M + 3H charge states. Conformational isomer interconversion rates were measured as a function of the trapping time for the M + 2H and M + 3H charge states. Candidate structures were proposed for all IMS bands observed. Protonation site, proline residue conformation, and side chain orientations were identified as the main motifs governing the conformational interconversion processes. Conformational dynamics from the solvent state distribution to the gas-phase "de-solvated" state distribution demonstrated that ATHP is "structured", and relative abundances are associated with the relative stability between the proposed conformers. The most stable ATHP M + 2H conformation at the "de-solvated" state corresponds to the AT hook motif observed in AT-rich DNA regions.
哺乳动物高迁移率族蛋白 HMGA2 包含三个 DNA 结合基序，与许多生理功能有关，包括致癌作用、肥胖、干细胞年轻化、人类身高和人类智力。在本文中，我们利用离子淌度质谱（TIMS-MS）研究了第三个 DNA 结合基序的构象动力学，使用“AT 钩”十肽单元（Lys(1)-Arg(2)-Prol(3)-Arg(4)-Gly(5)-Arg(6)-Prol(7)-Arg(8)-Lys(9)-Trp(10), ATHP）作为溶剂状态的函数。在电喷雾离子形成过程中保留了溶剂状态分布，并确定了 M + 2H和 M + 3H荷质比的多个 IMS 带。测量了 M + 2H和 M + 3H荷质比的俘获时间作为构象异构体转化速率的函数。提出了所有观察到的 IMS 带的候选结构。质子化位点、脯氨酸残基构象和侧链取向被确定为控制构象转化过程的主要基序。从溶剂状态分布到气相“去溶剂”状态分布的构象动力学表明，ATHP 是“结构化”的，相对丰度与所提出的构象之间的相对稳定性有关。在“去溶剂”状态下最稳定的 ATHP M + 2H构象对应于富含 AT 的 DNA 区域中观察到的 AT 钩基序。
