Integrative genetic element that reverses the usual target gene orientation

A genetic element integrating site specifically into a prokaryotic gene usually carries a copy of the 3' portion of that gene that restores the active gene even as the original is disrupted. A cryptic element in Mesorhizobium loti instead carries a copy of the 5' end of the tRNA gene into which it integrated. This has implications for the evolution of new integrase-site combinations.