SEMINAR

Insights into the pressure-induced conformational change of β2-microglobulin and its pathogenic variants

Abstract
Analyses of pressure-induced conformational transition of proteins give us additional information, such as changes in their molar volumes and conformational fluctuations upon transition (1). We investigated the pressure-induced folding/unfolding of β2-microglobulin (β2m), which is the causative protein of dialysis-related amyloidosis (2), and two of whose variants, ΔN6 and D76N, are known to be more prone to aggregation (3, 4). It was reported that refolding pathway of β2m at physiological pH was different from that of unfolding, and one of the refolding intermediate state, IT, is a putative amyloidogenic precursor state (5). The analysis of the results of the pressure-induced folding and unfolding of wild-type β2m revealed that the transition from the unfolded state to the putative amyloidogenic state needs a transient volumetric expansion. We are also investigating the properties of the aggregation-prone variants for the mechanism of the β2m amyloid fibril formation.

References
[1] K. Akasaka. (2006) Probing conformational fluctuation of proteins by pressure perturbation. Chem Rev 106, 1814-1835.
[2] K. Yanagi et al. (2012) The monomer-seed interaction mechanism in the formation of the β2-microglobulin amyloid fibril clarified by solution NMR techniques. J Mol Biol. 422, 390-402.
[3] V. Bellotti et al. (1998) Beta2-microglobulin can be refolded into a native state from ex vivo amyloid fibrils. Eur J Biochem 258, 61-67.
[4] S. Valleix et al. (2012) Hereditary systemic amyloidosis due to Asp76Asn variant β2-microglobulin. N Engl J Med 366, 2276-2283.
[5] M. Sakata et al. (2008) Kinetic coupling of folding and prolyl isomerization of beta2-microglobulin studied by mutational analysis. J Mol Biol. 382, 1242-1255.

BIOGRAPHY

2013-present: Lecturer, Institute of Advanced Technology, Kindai University
2005-2013: Assistant Professor, Institute for Protein Research, Osaka University
2005: PhD, Department of Macromolecular Science, Graduate School of Science, Osaka University

Research Fields and Interests:
Conformational changes of proteins upon various changes in solution conditions, including protein folding, local conformational change relevant to function, and amyloid fibril formation. To probe conformational changes of proteins, we use various spectroscopic methods, including fluorescence and NMR. We are also developing analytical methods of HSQC signal data for condition-dependent protein conformational change. From 2013, we are also investigating the pressure effect on the protein conformation and dynamics.

Selected Publications:
Konuma, T., Sakurai, K., Yagi, M., Goto, Y., Fujisawa, T. and Takahashi, S. (2015) Highly Collapsed Conformation of the Initial Folding Intermediates of β-Lactoglobulin with Non-Native α-Helix. J. Mol. Biol., in press. [PMID: 26232603]

Adachi, M., So, M., Sakurai, K., Kardos, J. and Goto, Y. (2015) Supersaturation-limited and Unlimited Phase Transitions Compete to Produce the Pathway Complexity in Amyloid Fibrillation. J. Biol. Chem. 290, 18134-18145. [PMID: 26063798]

Sakurai, K., Nakahata, R., Lee, Y.-H., Kardos, J., Ikegami, T. and Goto, Y. (2015) Effects of a reduced disulfide bond on aggregation properties of the human IgG1 CH3 domain. Biochim. Biophys. Acta, in press. [PMID: 25748879]

Kitayama, H., Yoshimura, Y., So, M., Sakurai, K., Yagi, H. and Goto, Y. (2015) A common mechanism underlying amyloid fibrillation and protein crystallization revealed by the effects of ultrasonication. Biochim. Biophys. Acta 1834, 2640-2646. [PMID: 24096102]

Konuma, T., Lee, Y.-H., Goto, Y. and Sakurai, K. (2013) Principal component analysis of chemical shift perturbation data of a multiple-ligand-binding system for elucidation of respective binding mechanism. Proteins 81, 107-118. [PMID: 22927212]