Ferritin Assembly Revisited: A Time-Resolved Small-Angle X-ray Scattering Study

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• 作者：Daisuke Sato ; Hideaki Ohtomo ; Yoshiteru Yamada ; Takaaki Hikima ; Atsushi Kurobe ; Kazuo Fujiwara ; Masamichi Ikeguchi
• 刊名：Biochemistry
• 出版年：2016
• 出版时间：January 19, 2016
• 年：2016
• 卷：55
• 期：2
• 页码：287-293
• 全文大小：417K
• ISSN：1520-4995

文摘

The assembly reaction of Escherichia coli ferritin A (EcFtnA) was studied using time-resolved small-angle X-ray scattering (TR-SAXS). EcFtnA forms a cagelike structure that consists of 24 identical subunits and dissociates into dimers at acidic pH. The dimer maintains nativelike secondary and tertiary structures and is able to reassemble into a 24-mer when the pH is increased. The reassembly reaction was induced by pH jump, and reassembly was followed by TR-SAXS. Time-dependent changes in the forward scattering intensity and in the gyration radius suggested the existence of a significant population of intermediate oligomers during the assembly reaction. The initial reaction was a mixture of second- and third-order reactions (formation of tetramers and hexamers) from the protein concentration dependence of the initial velocity. The time-dependent change in the SAXS profile was roughly explained by a simple model in which only tetramers, hexamers, and dodecamers were considered as intermediates.