The mannose-specific lectin domains of Flo1p from Saccharomyces cerevisiae and Lg-Flo1p from S. pastorianus: crystallization and preliminary X-ray diffraction analysis of the adhesin-carbohydrate complexes

摘要

Flo1p and Lg-Flo1p are two cell-wall adhesins belonging to the Flo (flocculation) protein family from the yeasts Saccharomyces cerevisiae and S. pastorianus. The main function of these modular proteins endowed with calcium-dependent lectin activity is to mediate cell-cell adhesion events during yeast flocculation, a process which is well known at the cellular level but still not fully characterized from a molecular perspective. Recently, structural features of the N-terminal Flo lectin domains, including the N-terminal domain of Lg-Flo1p (N-Lg-Flo1p), and their interactions with carbohydrate molecules have been investigated. However, structural data concerning the N-terminal domain of Flo1p (N-Flo1p), which is the most specific among the Flo proteins, are missing and information about the N-Lg-Flo1p-carbohydrate interaction still lacks detailed structural insight. Here, the crystallization and preliminary X-ray characterization of the apo form and the mannose complex of N-Flo1p and X-ray analysis of N-Lg-Flo1p crystals soaked in alpha-1,2-mannobiose are reported. The N-Flo1p crystals diffracted to a resolution of 1.43 angstrom in the case of the apo form and to 2.12 angstrom resolution for the mannose complex. Both crystals were orthorhombic and belonged to space group P2(1)2(1)2(1), with one molecule in the asymmetric unit. The N-Lg-Flo1p-alpha-1,2-mannobiose complex crystal diffracted to 1.73 angstrom resolution and belonged to the monoclinic space group P12(1)1 with two molecules in the asymmetric unit.