title: Yersinia pestis lacZ expresses a beta-galactosidase with low enzymatic activity.
abstract: Although very little, if any, beta-galactosidase activity is detected in Yersinia pestis by a standard Miller assay, we found that Y. pestis KIM6+ cells formed blue colonies on plates containing 5-bromo-4-chloro-3-indolyl-beta-D-galactoside (X-gal). Searches of the Y. pestis genome databases revealed the presence of noncontiguous sequences highly homologous to Escherichia coli lacZ, lacY, and lacI. Yersinia pestis lacZ is predicted to encode a 1060 amino-acid protein with 62% identity and 72% similarity to beta-galactosidase from E. coli. A deletion in the Y. pestis lacZ gene caused the formation of white colonies on X-gal-containing plates and beta-galactosidase activity was at background levels in the KIM6+lacZ mutant, while the complemented strain expressed about 190 Miller units. The Y. pestis lacZ promoter was not regulated by isopropylthiogalactoside or glucose. Finally, uptake of lactose by Y. pestis may be impaired.
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics, MS415 Medical Center, University of Kentucky, Lexington, 40536-0298, USA. bobrov@pop.uky.edu
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Bobrov
authors.forename: Robert D
authors.initials: RD
authors.lastname: Perry
mesh_terms: D000595:Amino Acid Sequence; D004269:DNA, Bacterial / Q000235:genetics; D015870:Gene Expression; D007763:Lac Operon; D008969:Molecular Sequence Data; D015010:Yersinia pestis / Q000201:enzymology* / Q000235:genetics*; D001616:beta-Galactosidase / Q000235:genetics* / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D001616:beta-Galactosidase