Phase‐variation of pyelonephritis‐associated pili in Escherichia coli: evidence for transcriptional regulation.

摘要: The regulation of pyelonephritis-associated pili (pap) pilin gene transcription has been examined using two operons (pap-17 and pap-21) isolated from the pyelonephritogenic Escherichia coli strain C1212. DNA sequence analysis E. minicell were used to map genes (papB papI) within regulatory regions both pap-17 pap-21, protein products these identified. Pilin transcription, initiated at papBA promoter, was monitored by constructing single copy operon fusions with lacZYA in K-12. Inoculation (pap'-lac) strains onto solid M9 minimal medium containing glycerol Lac indicator X-gal (M9-Glycerol) yielded Lac+ Lac- colony phenotypes. ("phase on') off') phenotypes heritable since reinoculation M9-Glycerol bacteria picked colonies gave rise a much higher fraction than colonies. Measurement phase transition rates for (pap17'-lac) inoculated showed that Lac(-)----Lac+ frequency (1.57 X 10(-4)/cell/generation) reduced 35-fold when cells glucose (M9-Glucose). However, Lac+----Lac-transition obtained (2.60 10(-2)/cell/generation) 1.4-fold lower compared results M9-Glucose. In contrast, lowering incubation temperature cultures 37 degrees C 23 caused all shift state.(ABSTRACT TRUNCATED AT 250 WORDS)