1. Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aoba-yama 6-6-11-606, Sendai 980-8579, Japan, Polymer Chemistry Laboratory, RIKEN Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan, and Functional Protein Research Group, Research Institute of Genome-based Biofactory (RIGB), National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira, Sapporo 062-8517, Japan