We will continue our isolation and characterization of mutations that affect transposase expression at steps subsequent to transcription initiation in order to determine why translation of the transposase gene is so rare, to assess the interplay between translation and messenger degradation, and to determine the roles of these events in IS10 anti-sense inhibition. We will analyze bacterium E.coli mutant strains lacking IHF and/or HU to determine the relative contributions of these, and any other related accessory host factors present in wild type cells, to the activity of IS10 outside ends and to host factor inhibition of transposase expression in vivo. We will also try to understand why E.coli uses IHF to regulate IS10 transposition (and other processes) by examining changes in IHF levels under different growth conditions. Finally, using strains lacking known host factors, we will isolate revertants in which outside end activity is restored in hopes of identifying genes for additional accessory proteins. Depending on the progress made in (1) and (2), we may initiate a new search for E.coli mutants defective in the transposition reaction.
