1pbg
From Proteopedia
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THE THREE-DIMENSIONAL STRUCTURE OF 6-PHOSPHO-BETA GALACTOSIDASE FROM LACTOCOCCUS LACTIS
Overview
BACKGROUND: The enzyme 6-phospho-beta-galactosidase hydrolyzes, phospholactose, the product of a phosphor-enolpyruvate-dependent, phosphotransferase system. It belongs to glycosidase family 1 and no, structure has yet been published for a member of this family. RESULTS: The, crystal structure of 6-phospho-beta-galactosidase was determined at 2.3 A, resolution by multiple isomorphous replacement, using the wild-type enzyme, and a designed cysteine mutant. A second crystal form, found with the, mutant enzyme, was solved by molecular replacement, yielding the, conformation of two chain loops that are invisible in the first crystal, form. The active center, located through catalytic residues identified in, previous studies, cannot be accessed by the substrate if the two loops are, in their defined conformation. The enzyme contains a (beta alpha)8 barrel, and the relationship of its chain fold to that of other glycosidases has, been quantified. As a side issue, we observed that a cysteine point mutant, designed for X-ray analysis crystallized mainly as a symmetric dimer, around an intermolecular disulfide bridge formed by the newly introduced, cysteine. CONCLUSIONS: The presented analysis provides a basis on which to, model all other family 1 members and thereby will help in elucidating the, catalytic mechanisms of these sequence-related enzymes. Moreover, this, enzyme belongs to a superfamily of glycosidases sharing a (beta alpha)8, barrel with catalytic glutamates/aspartates at the ends of the fourth and, the seventh strands of the beta barrel.
About this Structure
1PBG is a Single protein structure of sequence from Lactococcus lactis with SO4 as ligand. Active as 6-phospho-beta-galactosidase, with EC number 3.2.1.85 Full crystallographic information is available from OCA.
Reference
The three-dimensional structure of 6-phospho-beta-galactosidase from Lactococcus lactis., Wiesmann C, Beste G, Hengstenberg W, Schulz GE, Structure. 1995 Sep 15;3(9):961-8. PMID:8535789
Page seeded by OCA on Tue Nov 20 23:39:53 2007
