Surface-exposed histone-like protein a modulates adherence of Streptococcus gallolyticus to colon adenocarcinoma cells.
Streptococcus gallolyticus (formerly known as Streptococcus bovis biotype I) is a low-grade opportunistic pathogen which is considered to be associated with colon cancer. It is thought that colon polyps or tumors are the main portal of entry for this bacterium and that heparan sulfate proteoglycans (HSPGs) at the colon tumor cell surface are involved in bacterial adherence during the first stages of infection. In this study, we have shown that the histone-like protein A (HlpA) of S. gallolyticus is a genuine anchorless bacterial surface protein that binds to lipoteichoic acid (LTA) of the gram-positive cell wall in a growth phase-dependent manner. In addition, HlpA was shown to be one of the major heparin-binding proteins of S. gallolyticus able to bind to the HSPG-expressing colon tumor cell lines HCT116 and HT-29. Strikingly, although wild-type levels of HlpA appeared to contribute to adherence, coating of additional HlpA at the bacterial surface resulted in reduced binding to colon tumor cells. This may be explained by the fact that heparan sulfate and LTA compete for the same binding site in HlpA. Altogether, this study implies that HlpA serves as a fine-tuning factor for bacterial adherence.
Boleij
Annemarie
A
Department of Laboratory Medicine, Nijmegen Institutes for Infection, Inflammation and Immunity and Oncology of the Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, The Netherlands.
Schaeps
Renée M J
RM
de Kleijn
Stan
S
Hermans
Peter W
PW
Glaser
Philippe
P
Pancholi
Vijay
V
Swinkels
Dorine W
DW
Tjalsma
Harold
H
D018829:Adhesins, Bacterial / Q000502:physiology*; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000502:physiology*; D045744:Cell Line, Tumor; D006493:Heparin / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000502:physiology*; D011485:Protein Binding; D016985:Streptococcus bovis / Q000472:pathogenicity*
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D008565:Membrane Proteins; D006493:Heparin