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
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.
BourgogneA.,
HilsenbeckS. G.,
DunnyG. M.,
MurrayB. E.(2006). Comparison of OG1RF and an isogenic fsrB deletion mutant by transcriptional analysis: the Fsr system of Enterococcus faecalis is more than the activator of gelatinase and serine protease. J Bacteriol 188:2875–2884 [View Article][PubMed]
BragaT. M.,
MarujoP. E.,
PombaC.,
LopesM. F.(2011). Involvement, and dissemination, of the enterococcal small multidrug resistance transporter QacZ in resistance to quaternary ammonium compounds. J Antimicrob Chemother 66:283–286 [View Article][PubMed]
DowerW. J.,
MillerJ. F.,
RagsdaleC. W.(1988). High efficiency transformation of E. coli by high voltage electroporation. Nucleic Acids Res 16:6127–6145 [View Article][PubMed]
DunnyG. M.,
LeeL. N.,
LeBlancD. J.(1991). Improved electroporation and cloning vector system for Gram-positive bacteria. Appl Environ Microbiol 57:1194–1201[PubMed]
EatonT. J.,
GassonM. J.(2001). Molecular screening of Enterococcus virulence determinants and potential for genetic exchange between food and medical isolates. Appl Environ Microbiol 67:1628–1635 [View Article][PubMed]
Galloway-PeñaJ. R.,
BourgogneA.,
QinX.,
MurrayB. E.(2011). Diversity of the fsr-gelE region of the Enterococcus faecalis genome but conservation in strains with partial deletions of the fsr operon. Appl Environ Microbiol 77:442–451 [View Article][PubMed]
GasparF.,
TeixeiraN.,
Rigottier-GoisL.,
MarujoP.,
Nielsen-LeRouxC.,
CrespoM. T.,
LopesM. F.,
SerrorP.(2009). Virulence of Enterococcus faecalis dairy strains in an insect model: the role of fsrB and gelE
. Microbiology 155:3564–3571 [View Article][PubMed]
GilmoreM. S.,
CoburnP. S.,
NallapareddyS. R.,
MurrayB. E.2002; Enterococcal virulence. The Enterococci – Pathogenesis, Molecular Biology, and Antibiotic Resistance301–354GilmoreM. S.
Washington, DC: American Society for Microbiology;
GrantS. G.,
JesseeJ.,
BloomF. R.,
HanahanD.(1990). Differential plasmid rescue from transgenic mouse DNAs into Escherichia coli methylation-restriction mutants. Proc Natl Acad Sci U S A 87:4645–4649 [View Article][PubMed]
HancockL. E.,
PeregoM.(2004). The Enterococcus faecalis fsr two-component system controls biofilm development through production of gelatinase. J Bacteriol 186:5629–5639 [View Article][PubMed]
LawJ.,
BuistG.,
HaandrikmanA.,
KokJ.,
VenemaG.,
LeenhoutsK.(1995). A system to generate chromosomal mutations in Lactococcus lactis which allows fast analysis of targeted genes. J Bacteriol 177:7011–7018[PubMed]
LeenhoutsK.,
BuistG.,
BolhuisA.,
ten BergeA.,
KielJ.,
MierauI.,
DabrowskaM.,
VenemaG.,
KokJ.(1996). A general system for generating unlabelled gene replacements in bacterial chromosomes. Mol Gen Genet 253:217–224 [View Article][PubMed]
LopesM. F.,
PereiraC. I.,
RodriguesF. M.,
MartinsM. P.,
MimosoM. C.,
BarrosT. C.,
Figueiredo MarquesJ. J.,
TenreiroR. P.,
AlmeidaJ. S.,
Barreto CrespoM. T.(1999). Registered designation of origin areas of fermented food products defined by microbial phenotypes and artificial neural networks. Appl Environ Microbiol 65:4484–4489[PubMed]
MaguinE.,
PrévostH.,
EhrlichS. D.,
GrussA.(1996). Efficient insertional mutagenesis in lactococci and other Gram-positive bacteria. J Bacteriol 178:931–935[PubMed]
MohamedJ. A.,
MurrayB. E.(2006). Influence of the fsr locus on biofilm formation by Enterococcus faecalis lacking gelE
. J Med Microbiol 55:1747–1750 [View Article][PubMed]
MundtJ. O.(1986). Enterococci. Bergey’s Manual of Systematic Bacteriology1063–1065SneathP. H. A.,
MairN. S.,
SharpeM. E.,
HoltJ. G.
Baltimore: Williams & Wilkins;
NakayamaJ.,
CaoY.,
HoriiT.,
SakudaS.,
AkkermansA. D.,
de VosW. M.,
NagasawaH.(2001a). Gelatinase biosynthesis-activating pheromone: a peptide lactone that mediates a quorum sensing in Enterococcus faecalis
. Mol Microbiol 41:145–154 [View Article][PubMed]
NakayamaJ.,
CaoY.,
HoriiT.,
SakudaS.,
NagasawaH.(2001b). Chemical synthesis and biological activity of the gelatinase biosynthesis-activating pheromone of Enterococcus faecalis and its analogs. Biosci Biotechnol Biochem 65:2322–2325 [View Article][PubMed]
NakayamaJ.,
KariyamaR.,
KumonH.(2002). Description of a 23.9-kilobase chromosomal deletion containing a region encoding fsr genes which mainly determines the gelatinase-negative phenotype of clinical isolates of Enterococcus faecalis in urine. Appl Environ Microbiol 68:3152–3155 [View Article][PubMed]
ParkS. Y.,
KimK. M.,
LeeJ. H.,
SeoS. J.,
LeeI. H.(2007). Extracellular gelatinase of Enterococcus faecalis destroys a defense system in insect hemolymph and human serum. Infect Immun 75:1861–1869 [View Article][PubMed]
QinX.,
SinghK. V.,
WeinstockG. M.,
MurrayB. E.(2000). Effects of Enterococcus faecalis fsr genes on production of gelatinase and a serine protease and virulence. Infect Immun 68:2579–2586 [View Article][PubMed]
QueY. A.,
HaefligerJ. A.,
FrancioliP.,
MoreillonP.(2000). Expression of Staphylococcus aureus clumping factor A in Lactococcus lactis subsp. cremoris using a new shuttle vector. Infect Immun 68:3516–3522 [View Article][PubMed]
SifriC. D.,
MylonakisE.,
SinghK. V.,
QinX.,
GarsinD. A.,
MurrayB. E.,
AusubelF. M.,
CalderwoodS. B.(2002). Virulence effect of Enterococcus faecalis protease genes and the quorum-sensing locus fsr in Caenorhabditis elegans and mice. Infect Immun 70:5647–5650 [View Article][PubMed]
ThomasV. C.,
HiromasaY.,
HarmsN.,
ThurlowL.,
TomichJ.,
HancockL. E.(2009). A fratricidal mechanism is responsible for eDNA release and contributes to biofilm development of Enterococcus faecalis
. Mol Microbiol 72:1022–1036 [View Article][PubMed]
ThurlowL. R.,
ThomasV. C.,
HancockL. E.(2009). Capsular polysaccharide production in Enterococcus faecalis and contribution of CpsF to capsule serospecificity. J Bacteriol 191:6203–6210 [View Article][PubMed]
VebøH. C.,
SnipenL.,
NesI. F.,
BredeD. A.(2009). The transcriptome of the nosocomial pathogen Enterococcus faecalis V583 reveals adaptive responses to growth in blood. PLoS ONE 4:e7660 [View Article][PubMed]
VebøH. C.,
SolheimM.,
SnipenL.,
NesI. F.,
BredeD. A.(2010). Comparative genomic analysis of pathogenic and probiotic Enterococcus faecalis isolates, and their transcriptional responses to growth in human urine. PLoS ONE 5:e12489 [View Article][PubMed]
ZhuY.,
InouyeM.(2002). The role of the G2 box, a conserved motif in the histidine kinase superfamily, in modulating the function of EnvZ. Mol Microbiol 45:653–663 [View Article][PubMed]
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