A DNA-SEQUENCE CONTAINING THE CONTROL REGIONS OF THE MALEFG AND MALK-LAMB OPERONS IN ESCHERICHIA-COLI-K12

The malB region in E. coli is composed of 2 operons, malEFG and malK-lamB, transcribed divergently from a control region located between the malE and malK genes. The DNA sequence of a 600 base pair segment which contains the sites necessary for initiation of transcription of the malB operons and the translation start sites for malE and malK was determined. The position of a 147 base pair deletion (malB.DELTA.100) in this sequence was also determined. The control region contains 2 short segments (about 35 base pairs) showing unusual distributions of bases: the GC content (85%) is higher than average and most of the purines (85%) are on one strand. The possible relevance of this and other salient features of the DNA sequence to the mechanisms by which the expression of the malB region is positively regulated is discussed.