The gcvB RNA gene encodes a small non-coding RNA involved in the regulation of a number of amino acid transport systems as well as amino acid biosynthetic genes. The GcvB gene is found in enteric bacteria such as Escherichia coli. GcvB regulates genes by acting as an antisense binding partner of the mRNAs for each regulated gene. This binding is dependent on binding to a protein called Hfq. Transcription of the GcvB RNA is activated by the adjacent GcvA gene and repressed by the GcvR gene. A deletion of GcvB RNA from Y. pestis changed colony shape as well as reducing growth. It has been shown by gene deletion that GcvB is a regulator of acid resistance in E. coli. GcvB enhances the ability of the bacterium to survive low pH by upregulating the levels of the alternate sigma factor RpoS. A p