“…From our work with the chaperone hybrids, however, the cause of low PcrH expression must reside in the extreme N terminus, since Hyb9, which essentially contained all of PcrH except for the first 17 LcrH amino acids, was expressed at roughly LcrH-like levels in Yersinia. It has been established that the 5Ј end of many E. coli genes is responsible for control of translation efficiency (12) as well as a wide variety of virulence determinants produced by numerous bacterial pathogens (17,19,20,50,57,61). Therefore, minor codons in the extreme N terminus of LcrH might have evolved to control the translation efficiency of this important regulatory molecule, a concept we are currently exploring.…”