Pleiotrophic effects of 2 Enterococcus faecalis sagA-like genes, salA and salB, which encode proteins that are antigenic during human infection, on biofilm formation and binding to collagen type i and fibronectin.
BACKGROUND
We have shown previously that Enterococcus faecium SagA has broad-spectrum binding to extracellular matrix (ECM) proteins. In the present study, 2 sagA-like genes, salA and salB, were identified in Enterococcus faecalis.


METHODS
We compared the salA and salB mutants; their parental strain, OG1RF; and the salB-complemented strain for binding to ECM proteins and biofilm formation.


RESULTS
The salB mutant (TX5123) grew more slowly but showed greater binding (approximately 10%-20% of cells bound) to fibronectin (FN) and collagen type I (CI) than did OG1RF (approximately 1% of cells bound) (P<.001). Although TX5123 showed decreased biofilm formation in tryptic soy broth plus 0.25% glucose (TSBG) (P<.001 vs. OG1RF), a marked increase in biofilm formation was shown by TX5123 but not by OG1RF when they were grown in TSBG plus horse serum (HS) or TSBG plus FN, and the increase was coincident with increased attachment and hydrophobicity of TX5123. Complementation of the salB mutant restored the wild-type phenotypes.


CONCLUSIONS
Whether SalB expression is ever sufficiently low in vivo to enhance adherence to ECM proteins or the serum-elicited increase in biofilm formation seen with the salB mutant in vitro is not currently known, but it is a potential way in which this organism could increase its adherence and biofilm formation during infection.
Mohamed
Jamal A
JA
Division of Infectious Disease, Department of Internal Medicine, University of Texas Medical School, Houston 77030, USA.
Teng
Fang
F
Nallapareddy
Sreedhar R
SR
Murray
Barbara E
BE
D001422:Bacterial Adhesion / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D018441:Biofilms / Q000254:growth & development*; D024042:Collagen Type I / Q000378:metabolism; D013293:Enterococcus faecalis / Q000235:genetics / Q000502:physiology*; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism; D017353:Gene Deletion; D005816:Genetic Complementation Test; D008858:Microscopy, Phase-Contrast; D009154:Mutation; D010784:Photomicrography
D001426:Bacterial Proteins; D024042:Collagen Type I; D016326:Extracellular Matrix Proteins; D005353:Fibronectins