title: The Streptomyces coelicolor genome encodes a type I ribosome-inactivating protein.
abstract: Ribosome-inactivating proteins (RIPs) are cytotoxic N-glycosidases identified in numerous plants, but also constitute a subunit of the bacterial Shiga toxin. Classification of plant RIPs is based on the absence (type I) or presence (type II) of an additional lectin module. In Shiga toxin, sugar binding is mediated by a distinct RIP-associated homopentamer. In the genome of two actinomycetes, we identified RIP-like proteins that resemble plant type I RIPs rather than the RIP subunit (StxA) of Shiga toxin. Some representatives of β- and γ-proteobacteria also contain genes encoding RIP-like proteins, but these are homologous to StxA. Here, we describe the isolation and initial characterization of the RIP-like gene product SCO7092 (RIPsc) from the Gram-positive soil bacterium Streptomyces coelicolor. The ripsc gene was expressed in Escherichia coli as a recombinant protein of about 30&emsp14;kDa, and displayed the characteristic N-glycosidase activity causing specific rRNA depurination. In Streptomyces lividans and E. coli, RIPsc overproduction resulted in a dramatic decrease in the growth rate. In addition, intracellular production was deleterious for Saccharomyces cerevisiae. However, when applied externally to microbial cells, purified RIPsc did not display antibacterial or antifungal activity, suggesting that it cannot enter these cells. In a cell-free system, however, purified S. coelicolor RIPsc protein displayed strong inhibitory activity towards protein translation.
authors.affiliation: Departamento de Biotecnología, División de Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana, Mexico City, Mexico.|Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Ana G
authors.initials: AG
authors.lastname: Reyes
authors.affiliation: Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Nick
authors.initials: N
authors.lastname: Geukens
authors.affiliation: Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Philip
authors.initials: P
authors.lastname: Gutschoven
authors.affiliation: Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, Katholieke Universiteit Leuven, B-3001 Heverlee-Leuven, Belgium.|VIB Department of Molecular Microbiology, Kasteelpark Arenberg 31, B-3001 Heverlee-Leuven, Belgium.
authors.forename: Stijn
authors.initials: S
authors.lastname: De Graeve
authors.affiliation: Centre of Microbial and Plant Genetics, Department of Microbial and Molecular Systems, Faculty of Bioscience Engineering, Katholieke Universiteit Leuven, B-3001 Heverlee-Leuven, Belgium.
authors.forename: René
authors.initials: R
authors.lastname: De Mot
authors.affiliation: Departamento de Biotecnología, División de Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana, Mexico City, Mexico.
authors.forename: Armando
authors.initials: A
authors.lastname: Mejía
authors.affiliation: Laboratory of Bacteriology, Rega Institute for Medical Research, Katholieke Universiteit Leuven, Minderbroedersstraat 10, B-3000 Leuven, Belgium.
authors.forename: Jozef
authors.initials: J
authors.lastname: Anné
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D016680:Genome, Bacterial; D006026:Glycoside Hydrolases / Q000378:metabolism; D014176:Protein Biosynthesis; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D054788:Ribosome Inactivating Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development; D048372:Streptomyces coelicolor / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D048170:Streptomyces lividans / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D006026:Glycoside Hydrolases; D054788:Ribosome Inactivating Proteins