Gene aggregation: evidence for a coming together of functionally related, not closely linked genes.

Abstract

Evidence that not closely linked genes of the arginine system in Escherichia coli occur as gene aggregates has been provided through the demonstration of relatively frequent pairs of concomitant mutations (enzyme-enzyme, enzyme-permease, enzyme-regulatory-gene-product). Gene aggregation is thought to be physiologically advantageous, evolutionarily selected for, and dependent on chromosomal folding and higher-order structure. The genesis of the double mutations may involve interactions of strand segments of juxtaposed portions of DNA helix.