TheEscherichia coliGcvB sRNA Uses Genetic Redundancy to ControlcycAExpression

Abstract

TheEscherichia colisRNA GcvB regulates several genes involved in transport of amino acids and peptides (sstT, oppA, dppA, andcycA). Two regions of GcvB from nt +124 to +161 and from nt +73 to +82 are complementary with essentially the same region of thecycAmRNA. Transcriptional fusions ofcycAtolacZshowed the region ofcycAmRNA that can pair with either region of GcvB is necessary for regulation by GcvB. However, mutations in either region ofgcvBpredicted to disrupt pairing betweencycAmRNA and GcvB did not alter expression of acycA-lacZtranslational fusion. A genetic analysis identified nts in GcvB necessary for regulation of thecycA-lacZfusion. The results show that either region of GcvB complementary tocycAmRNA can basepair with and independently represscycA-lacZand both regions need to be changed to cause a significant loss of repression.