Selective Feedback Inhibition and Repression of Two Aspartokinases in the Metabolism of Escherichia coli
This extract was created in the absence of an abstract.
Excerpt
INTRODUCTION
Regulation of diverse biosynthetic pathways by changes in concentrations of the ultimate end products is achieved by two distinct mechanisms:
-
repression of the synthesis of enzymes involved in the metabolic pathway.
-
specific inhibition, usually of the first enzymatic step, of the metabolic sequence, or feedback control.
In those situations where several end metabolites are derived from a common precursor, operation of these regulatory mechanisms poses a serious problem: overproduction of one end metabolite might lead to a reduction in the rate of the common intermediate below that needed for optimal biosynthesis of another end metabolite. We have therefore decided to study such a situation and have chosen the biosynthetic pathway leading from aspartic acid to lysine and threonine, in Escherichia coli K12.
[Graphics Excised].
So far, most of our studies have dealt with the first enzyme of this branched pathway, β-aspartokinase.
