COORDINATE, TEMPERATURE-SENSITIVE REGULATION OF THE 3 YERSINIA-ENTEROCOLITICA FLAGELLIN GENES

Yersinia enterocolitica cells, when cultured at 30 degrees C or below, are flagellated and motile. Cells cultured at 37 degrees C or above l ack flagella and are non-motile. To identify flagellin genes that are a target of this temperature-dependent regulation, a library of Y. ent erocolitica genomic inserts in a phage lambda vector was probed with t he Salmonella typhimurium fliC (flagellin) gene. A DNA fragment subclo ned from a recombinant phage which hybridizes with the probe complemen ts a non-motile S. typhimurium fliC(-)fljB(-) (flagellin-minus) mutant . DNA sequence analysis shows that Y. enterocolitica contains three ta ndem flagellin genes, designated fleA, fleB and fleC. All three genes are co-ordinately transcribed at low, but not high, temperature from f liA-dependent (sigma(F)) promoters. Flagellin transcription arrests ra pidly after upshift to 37 degrees C (host temperature). In contrast, f lagellin transcription resumes only after several generations when cel ls cultured at 37 degrees C are downshifted to 28 degrees C.