title: Peculiarity in crystal packing of anti-HIV lectin actinohivin in complex with α(1-2)mannobiose.
abstract: Previously, the anti-HIV lectin actinohivin (AH) was cocrystallized with the target α(1-2)mannobiose (MB) in the apparent space group P213. However, three MB-bound AH rotamers generated by ±120° rotations around the molecular pseudo-threefold rotation axis are packed randomly in the unit cell according to P212121 symmetry [Hoque et al. (2012). Acta Cryst. D68, 1671-1679]. It was found that the AH used for crystallization contains short peptides attached to the N-terminus [Suzuki et al. (2012). Acta Cryst. F68, 1060-1063], which cause packing disorder. In the present study, the fully mature homogeneous AH has been cocrystallized with MB into two new crystal forms at different pH. X-ray analyses of the two forms reveal that they have peculiar character in that the space groups are the same, P22121, and the unit-cell parameters are almost the same with the exception of the length of the a axis, which is doubled in one form. The use of homogeneous AH resulted in the absence of disorder in both crystals and an improvement in the resolution, thereby establishing the basis for AH binding to the target MB. In addition, the two crystal structures clarify the interaction modes between AH molecules, which is important knowledge for understanding the multiple binding effect generated when two AH molecules are linked together with a short peptide [Takahashi et al. (2011). J. Antibiot. 64, 551-557].
authors.affiliation: College of Science and Engineering, Iwaki Meisei University, Iwaki, Fukushima 970-8551, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Suzuki
authors.forename: Masaru
authors.initials: M
authors.lastname: Tsunoda
authors.forename: M Mominul
authors.initials: MM
authors.lastname: Hoque
authors.forename: Fang
authors.initials: F
authors.lastname: Zhang
authors.forename: Jiandong
authors.initials: J
authors.lastname: Jiang
authors.forename: Xiaoxue
authors.initials: X
authors.lastname: Zhang
authors.forename: Naomi
authors.initials: N
authors.lastname: Ohbayashi
authors.forename: Haruo
authors.initials: H
authors.lastname: Tanaka
authors.forename: Akio
authors.initials: A
authors.lastname: Takénaka
mesh_terms: D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry*; D018360:Crystallography, X-Ray; D023581:HIV Fusion Inhibitors / Q000737:chemistry*; D008351:Mannans / Q000737:chemistry; D037241:Mannose-Binding Lectins / Q000737:chemistry*; D008362:Mannosides / Q000737:chemistry*; D011897:Random Allocation
chemical_list: D001426:Bacterial Proteins; D023581:HIV Fusion Inhibitors; D008351:Mannans; D037241:Mannose-Binding Lectins; D008362:Mannosides; C424136:actinohivin protein, actinomycete
keywords: actinohivin; anti-HIV lectin; high-mannose-type glycan