title: lacZ--Y+ fusions in Escherichia coli. DNA sequencing reveals the eight N-terminal residues of lac permease as non-essential.
abstract: The nucleotide sequence of three lacZ- -Y+ fusions found among spontaneous lacY+ revertants of the lacY- mutant MAB16 in Escherichia coli is reported. MAB16 is a frameshift mutation in codon 6 of the lacY gene. DNA sequence analysis of the fusions shows the first eight N-terminal codons of the lacY gene can be replaced by 3, 39 or 804/805 N-terminal codons of the lacZ gene without impairing lac permease activity qualitatively.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D003062:Codon / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000302:isolation & purification*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins / Q000235:genetics*; D009004:Monosaccharide Transport Proteins; D009154:Mutation; D027981:Symporters
chemical_list: D003062:Codon; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D027981:Symporters; C021499:lactose permease