Bacteriophage T4 alpha-glucosyltransferase: a novel interaction with gp45 and aspects of the catalytic mechanism.
The bacteriophage T4 alpha- and beta-glucosyltransferases (AGT and BGT) catalyse the transfer of glucose from uridine diphosphoglucose to 5-hydroxymethyl cytosine of T4 DNA in an alpha- and beta-conformation, respectively. Following the 3D structure of BGT and a secondary structure alignment of AGT and BGT, we performed a site-directed mutagenesis of AGT. A two-domain structure was deduced, with an open substrate-free and a closed substrate-bound conformation. We also identified specific amino acids involved in DNA binding. The identification of a protein-protein interaction of AGT and gp45 which is a part of the T4 replication complex supports the idea that T4 DNA is alpha-glucosylated immediately after synthesis. BGT then glucosylates those hydroxymethyl cytosines not previously served by AGT.
Sommer
Nicole
N
Arbeitsgruppe Molekulare Genetik, Fakultät für Biologie, Ruhr-Universität Bochum, D-44780 Bochum, Germany. sommer@molbio.uni-luebeck.de
Depping
Reinhard
R
Piotrowski
Markus
M
Rüger
Wolfgang
W
D000595:Amino Acid Sequence; D017122:Bacteriophage T4 / Q000201:enzymology* / Q000235:genetics; D001665:Binding Sites; D002384:Catalysis; D004247:DNA / Q000737:chemistry*; D004789:Enzyme Activation; D005964:Glucosyltransferases / Q000737:chemistry* / Q000235:genetics; D008562:Membrane Glycoproteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011487:Protein Conformation; D015800:Protozoan Proteins; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship
D008562:Membrane Glycoproteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C429279:gp45 protein, Babesia bigemina; D004247:DNA; D005964:Glucosyltransferases