In the presence of leucine , binding of Lrp is reduced , resulting in reduced transcriptional activation of ilvIH expression .
It has been known that ilvIH promoter activity is under the positive control of Lrp .
Lrp-regulated genes in Salmonella include fimZ , for type 1 fimbria expression ( 67 ) ; ilvIH , for branched amino-acid biosynthesis ( 93 ) ; hisJ , for D-histidine utilization ( 44 ) ; traJ , for conjugal transfer of virulence plasmid pSLT ( 13 ) ; and pef , for pSLT plasmid-encoded fimbriae ( 74 ) .