W0464

Crystal Structure of a α-amylase from Thermophilic Halophile Bacteria, Halothermothrix orenii. Tien-Chye Tan¹, Yvette Y. Yien¹, Bharat K.C. Patel², Benjamin N. Mijts², Kunchithapadam Swaminathan ^1,3,*, ¹Dept. of Biological Sciences, National Univ. of Singapore, Singapore 117543, ²Microbial Discovery Research Unit, School of Biomolecular & Biomedical Sciences, Faculty of Science, Griffith Univ., Brisbane, Queensland 4111, Australia, ³Inst. of Molecular and Cell Biology, 30 Medical Drive, National Univ. of Singapore, Singapore 117609, *Corresponding author: K.S, dbsks@nus.edu.sg.

This report is on one of the two α-amylases from an organism that is both thermophilic and halophilic, studied by X-ray crystallography for the first time. α-amylase from the thermophilic halophile Halothermothrix orenii (AmyB, phylogenetically different from our previously reported AmyA) is a 599-residue protein. It is stable and active significantly, at 358 K, in starch solution containing NaCl (up to 10% w/v). The purified recombinant AmyB protein crystallizes in the monoclinic space group C2 with unit-cell parameters a = 225.85, b = 77.16 and c = 50.13 Å, β = 99.32° using hanging drop vapor diffusion method. The crystal diffracts X-rays to a resolution limit of 1.97 Å.