1JZ3

E. COLI (lacZ) BETA-GALACTOSIDASE-TRAPPED 2-DEOXY-GALACTOSYL ENZYME INTERMEDIATE

Summary for 1JZ3

• Entry DOI: 10.2210/pdb1jz3/pdb
• Related: 1DP0 1F49 1JYN 1JYV 1JYW 1JYX 1JYY 1JYZ 1JZ0 1JZ1 1JZ2 1JZ4 1JZ5 1JZ6 1JZ7 1JZ8
• Descriptor: Beta-Galactosidase, 2-deoxy-alpha-D-galactopyranose, MAGNESIUM ION, ... (7 entities in total)
• Functional Keywords: tim barrel (alpha/beta barrel), jelly-roll barrel, immunoglobulin, beta supersandwich, hydrolase
• Biological source: Escherichia coli
• Total number of polymer chains: 4
• Total formula weight: 476894.30

Authors

Juers, D.H.,Matthews, B.W. (deposition date: 2001-09-13, release date: 2001-12-07, Last modification date: 2024-11-13)

Primary citation

Juers, D.H.,Heightman, T.D.,Vasella, A.,McCarter, J.D.,Mackenzie, L.,Withers, S.G.,Matthews, B.W.
A Structural View of the Action of Escherichia Coli (Lacz) Beta-Galactosidase
Biochemistry, 40:14781-14794, 2001

PubMed Abstract: The structures of a series of complexes designed to mimic intermediates along the reaction coordinate for beta-galactosidase are presented. These complexes clarify and enhance previous proposals regarding the catalytic mechanism. The nucleophile, Glu537, is seen to covalently bind to the galactosyl moiety. Of the two potential acids, Mg(2+) and Glu461, the latter is in better position to directly assist in leaving group departure, suggesting that the metal ion acts in a secondary role. A sodium ion plays a part in substrate binding by directly ligating the galactosyl 6-hydroxyl. The proposed reaction coordinate involves the movement of the galactosyl moiety deep into the active site pocket. For those ligands that do bind deeply there is an associated conformational change in which residues within loop 794-804 move up to 10 A closer to the site of binding. In some cases this can be inhibited by the binding of additional ligands. The resulting restricted access to the intermediate helps to explain why allolactose, the natural inducer for the lac operon, is the preferred product of transglycosylation.

PubMed: 11732897
DOI: 10.1021/bi011727i

Experimental method

X-RAY DIFFRACTION (1.75 Å)