title: Molecular basis of beta-galactosidase alpha-complementation.
abstract: In previous studies, a cyanogen bromide peptide derived from amino-acid residues 3-92 of beta-galactosidase (EC 3.2.1.23; beta-D-galactoside galactohydrolase) was shown to have alpha-donor activity in intracistronic alpha-complementation. We have now isolated the defective beta-galactosidase alpha-acceptor protein from the deletion mutant strain M15 of Escherichia coli and find that it lacks residues 11-41 of betal-galactosidase. This is demonstrated by the isolation and sequence determination of a cyanogen bromide peptide from the M15 protein, which is identical to the corresponding peptide from beta-galactosidase except for the missing amino acids. We conclude that the alpha-donor peptide restores the region missing in the M15 protein.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D001426:Bacterial Proteins / Q000096:biosynthesis; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D003488:Cyanogen Bromide; D004926:Escherichia coli / Q000201:enzymology*; D005696:Galactosidases / Q000096:biosynthesis* / Q000302:isolation & purification; D005816:Genetic Complementation Test; D009154:Mutation; D010446:Peptide Fragments / Q000032:analysis
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D010446:Peptide Fragments; D005696:Galactosidases; D003488:Cyanogen Bromide