Mapping of thepolA locus ofEscherichia coli K12: Orientation of the amino- and carboxy-termini of the cistron

Abstract
Three mutations of thepolA cistron, the structural gene for DNA polymerase I ofE. coli, have been ordered by three factor transductional crosses. The three mutant polymerase species have altered properties which may be ascribed to defects located in different portions of the polypeptide chain. Our data indicate that the amino terminal end is encoded by the end of thepolA cistron nearer tometE and that transcription and translation proceed clockwise on theE. coli circular map towards therha locus.