title: Spontaneous deletions and flanking regions of the chromosomally inherited hemolysin determinant of an Escherichia coli O6 strain.
abstract: The hemolytic Escherichia coli strain 536 (O6) propagates spontaneous hemolysin-negative mutants at relatively high rates (10(-3) to 10(-4)). One type of mutant (type I) lacks both secreted (external) and periplasmic (internal) hemolysin activity (Hlyex-/Hlyin-) and in addition shows no mannose-resistant hemagglutination (Mrh-), whereas the other type (type II) is Hlyex-/Hlyin+ and Mrh+. The genetic determinants for hemolysin production (hly) and for mannose-resistant hemagglutination (mrh) of this strain are located on the chromosome. Hybridization experiments with DNA probes specific for various parts of the hly determinant reveal that mutants of type I have lost the total hly determinant, whereas those of type II lack only part of the hlyB that is essential for transport of hemolysin across the outer membrane. Using a probe that contains the end sequence of the plasmid pHly152-encoded hly determinant (adjacent to hlyB), we determined that a related sequence flanks also the hlyB-distal end of the chromosomal hly determinant of E. coli 536. In addition several other similar or even identical sequences are found in the vicinity of the hlyC- and the hlyB-distal ends of both the chromosomal and the plasmid hly determinants.
mesh_terms: D001483:Base Sequence; D002876:Chromosomes, Bacterial; D004926:Escherichia coli / Q000235:genetics* / Q000276:immunology; D005798:Genes, Bacterial; D006384:Hemagglutination / Q000187:drug effects; D006459:Hemolysin Factors; D006460:Hemolysin Proteins / Q000235:genetics*; D008358:Mannose / Q000494:pharmacology; D009693:Nucleic Acid Hybridization
chemical_list: D006460:Hemolysin Proteins; D008358:Mannose