title: Overexpression of Ipe protein from the coliphage mEp021 induces pleiotropic effects involving haemolysis by HlyE-containing vesicles and cell death.
abstract: Lysogenic Escherichia coli K-12 harbouring the prophage mEp021 displays haemolytic activity. From a genomic library of mEp021, we identified an open reading frame (ORF 4) that was responsible for the haemolytic activity. However, the ORF 4 sequence contains four initiation codons in the same frame: ORF 4.1-ORF 4.4, coding for 83-a.a., 82-a.a., 77-a.a. and 72-a.a. products, respectively. The expression of the cloned ORF 4.3, or inducer of pleiotropic effects (ipe), reproduced the haemolytic phenotype in a native strain carrying the gene hlyE(+), but not in the mutant hlyE(-) strain. The overexpression of Ipe induced several pleiotropic effects, such as the inhibition of cell growth and the deregulation of cell division, which resulted in a mixture of normal and desiccated-like cells: normal-filamentous, desiccated-like-filamentous bacilli, minicells etc. Other effects included abnormalities of the cell membrane, the production of vesicles containing HlyE, and finally, cell death. These events were analysed at the molecular level by microarray assays. The global transcription profile of E. coli K-12 strain MC4100, which expressed Ipe after 4 h, revealed differential expression of various genes, most of which were related either to cell membrane and murein biosynthesis or to cell division. The up-regulation of some of these transcripts was confirmed by qRT-PCR. Additional research is needed to determine whether these effects are directly related to Ipe activity or are consequences of the cellular responses to putative structural damage induced by Ipe.
authors.affiliation: Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico Nacional No. 2508, C.P. 07360, México D.F., Mexico.
authors.forename: Eva
authors.initials: E
authors.lastname: Martínez-Peñafiel
authors.forename: Fernando
authors.initials: F
authors.lastname: Fernández-Ramírez
authors.forename: Cecilia
authors.initials: C
authors.lastname: Ishida
authors.forename: Ruth
authors.initials: R
authors.lastname: Reyes-Cortés
authors.forename: Omar
authors.initials: O
authors.lastname: Sepúlveda-Robles
authors.forename: Gabriel
authors.initials: G
authors.lastname: Guarneros-Peña
authors.forename: Rosa María
authors.initials: RM
authors.lastname: Bermúdez-Cruz
authors.forename: Luis
authors.initials: L
authors.lastname: Kameyama
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002455:Cell Division / Q000235:genetics; D003090:Coliphages / Q000235:genetics*; D048168:Escherichia coli K12 / Q000235:genetics / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000502:physiology; D006460:Hemolysin Proteins / Q000235:genetics* / Q000502:physiology; D006461:Hemolysis / Q000235:genetics; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D012756:Sheep / Q000097:blood; D015854:Up-Regulation
chemical_list: D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C574621:Ipe protein, E coli; C119944:hlyE protein, E coli