Genetic Characterization of the Yersiniae Cold Growth Phenomenon

Genetic Characterization of the Yersiniae Cold Growth Phenomenon

The yersinaie are psychotropic (able to grow at cold temperatures) Gram negative enterobacteriae that include 3 human pathogens: Yersinia pestis (the etiological agent of the black-death), Yersinia enterocolitica and Yersinia pseudotuberculosis (both causing self-limiting gastro-intestinal disorders). Y. enterocolitica, in particular, is an emerging food-borne illness and threat in the U.S. Since refrigeration is the dominant method of food preservation, an examination of the genetic basis of the yersiniae cold adaptation characteristics could yield considerable benefit. Recently, it has been shown that PNPase, an mRNA degrading exoribonuclease, is required for the yersinaie to grow at cold temperatures (~4-10°C). Furthermore, a recent microarray analysis of E. coli subjected to cold shock revealed that ymoA is upregulated. ymoA encodes the gene product YmoA which acts in concert with positively charged histone-like proteins to bind to DNA reducing/regulating transcription of bound genes. In this work, we found a yersiniaeymoA mutant to be reduced in its cold-growth capability. Furthermore, scanning tetra alanine mutagenesis of the ymoA gene was used to generate 17 tetra alanine ymoAvariants mutated from the amino terminus to the carboxy terminus of the encoded gene product. Preliminary data has suggested that alanine mutations near the amino terminus of YmoA results in cold-growth defects perhaps localizing the cold growth affect to a particular region of the protein.