title: The incongruent gelatinase genotype and phenotype in Enterococcus faecalis are due to shutting off the ability to respond to the gelatinase biosynthesis-activating pheromone (GBAP) quorum-sensing signal.
abstract: The concomitant presence of a complete fsr quorum-sensing system and gelE-sprE operons in Enterococcus faecalis is known to be essential for the detection of gelatinase activity. However, there are reports of the absence of gelatinase activity despite the presence of complete fsr and gelE loci. In order to understand this incongruence between genotype and phenotype we sequenced fsr and gelE loci of the E. faecalis LN68 strain, which was previously found to carry both operons but to lack gelatinase activity. Of the 59 nucleotide differences detected compared with the gelatinase-positive V583 strain, we found a nonsense mutation (a premature STOP codon) predicted to truncate the ATPase sensor domain of the FsrC protein, responsible for sensing and transducing the signal from the quorum-sensing molecule. Strain LN68 was highly affected in the expression of the gelE and sprE genes, further supporting the lack of Fsr-dependent gelE induction. When we constructed a V583 mutant with the same premature stop mutation in the fsrC gene the resulting strain was no longer able to degrade gelatin. We conclude that the reduced ability to transduce the quorum-sensing signal of the prematurely truncated FsrC protein is sufficient to explain the negative gelatinase phenotype. As the incongruent genotype and phenotype is detected in natural isolates, we believe that the silencing of the quorum-sensing system Fsr may be beneficial for some E. faecalis strains.
authors: IBET, Quinta do Marquês, Estação Agronómica Nacional, Apartado 12, 2781-901 Oeiras, Portugal.|Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127, 2781-901 Oeiras, Portugal.
authors: Neuza
authors: N
authors: Teixeira
authors: Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127, 2781-901 Oeiras, Portugal.
authors: Sofia
authors: S
authors: Santos
authors: Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127, 2781-901 Oeiras, Portugal.
authors: Paulo
authors: P
authors: Marujo
authors: Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors: Ryoji
authors: R
authors: Yokohata
authors: Division of Biology, Kansas State University, 19 Ackert Hall, Manhattan, KS 66506, USA.
authors: Vijayalakshmi S
authors: VS
authors: Iyer
authors: Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
authors: Jiro
authors: J
authors: Nakayama
authors: Division of Biology, Kansas State University, 19 Ackert Hall, Manhattan, KS 66506, USA.
authors: Lynn E
authors: LE
authors: Hancock
authors: AgroParisTech, UMR Micalis, F-78350 Jouy-en-Josas, France.|INRA, UMR1319 Micalis, F-78350 Jouy-en-Josas, France.
authors: Pascale
authors: P
authors: Serror
authors: IBET, Quinta do Marquês, Estação Agronómica Nacional, Apartado 12, 2781-901 Oeiras, Portugal.|Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127, 2781-901 Oeiras, Portugal.
authors: Maria de Fátima
authors: MF
authors: Silva Lopes
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D013293:Enterococcus faecalis / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D018093:Gelatinases / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005838:Genotype; D007783:Lactones / Q000378:metabolism*; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000378:metabolism*; D010641:Phenotype; D053038:Quorum Sensing; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; D007783:Lactones; D010456:Peptides, Cyclic; C438382:gelatinase biosynthesis-activating pheromone; D018093:Gelatinases