Key points are not available for this paper at this time.
Fusobacterium nucleatum is a Gram-negative anaerobe associated with various human infections, including periodontal diseases and preterm birth. A novel FadA adhesin was recently identified for host-cell binding. It consists of 129 amino acid residues, with an 18-amino acid signal peptide. Expression of FadA in Escherichia coli enhanced bacterial binding to host epithelial and endothelial cells. In both E. coli and F. nucleatum, FadA exists in two forms, the intact pre-FadA and the secreted mature FadA (mFadA), with pre-FadA anchored in the inner membrane and mFadA secreted outside the bacteria. Pre-FadA and mFadA formed high Mr complexes. When each form was purified to a single species, mFadA was soluble at neutral pH, whereas pre-FadA was insoluble. Pre-FadA became soluble when mixed with mFadA or under acidic pH. When fluorescence-labeled mFadA alone was added to the epithelial cells, no binding was detected. However, when mixed with nonlabeled pre-FadA, binding and invasion of mFadA into epithelial cells was observed. FadA is a unique bacterial adhesin/invasin in that it utilizes its own two forms for both structural and functional purposes. The pre-FadA-mFadA complex is probably anchored in the inner membrane and protrudes through the outer membrane. Internalization of the pre-FadA-mFadA ensures invasion of the bacteria into the host cells. Fusobacterium nucleatum is a Gram-negative anaerobe associated with various human infections, including periodontal diseases and preterm birth. A novel FadA adhesin was recently identified for host-cell binding. It consists of 129 amino acid residues, with an 18-amino acid signal peptide. Expression of FadA in Escherichia coli enhanced bacterial binding to host epithelial and endothelial cells. In both E. coli and F. nucleatum, FadA exists in two forms, the intact pre-FadA and the secreted mature FadA (mFadA), with pre-FadA anchored in the inner membrane and mFadA secreted outside the bacteria. Pre-FadA and mFadA formed high Mr complexes. When each form was purified to a single species, mFadA was soluble at neutral pH, whereas pre-FadA was insoluble. Pre-FadA became soluble when mixed with mFadA or under acidic pH. When fluorescence-labeled mFadA alone was added to the epithelial cells, no binding was detected. However, when mixed with nonlabeled pre-FadA, binding and invasion of mFadA into epithelial cells was observed. FadA is a unique bacterial adhesin/invasin in that it utilizes its own two forms for both structural and functional purposes. The pre-FadA-mFadA complex is probably anchored in the inner membrane and protrudes through the outer membrane. Internalization of the pre-FadA-mFadA ensures invasion of the bacteria into the host cells. Fusobacterium nucleatum is a Gram-negative anaerobe associated with various human infections. It is ubiquitous to the oral cavity and is implicated in periodontal diseases (1Moore W.E. Moore L.V. Periodontology 2000. 1994; 5: 66-77Crossref PubMed Scopus (792) Google Scholar). The organism coaggregates with microbial species in the oral cavity, playing a critical role in periodontal plaque formation (2Kolenbrander P.E. London J. J. Bacteriol. 1993; 175: 3247-3252Crossref PubMed Scopus (484) Google Scholar). It is also isolated from infections and abscesses of other parts of the body and is one of the most prevalent species in human intrauterine infections (3Chaim W. Mazor M. Arch. Gynecol. Obstet. 1992; 251: 1-7Crossref PubMed Scopus (52) Google Scholar, 4Hill G.B. Clin. Infect. Dis. 1993; 16: 423-424Crossref PubMed Scopus (40) Google Scholar, 5Watts D.H. Krohn M.A. Hillier S.L. Eschenbach D.A. Obstet. Gynecol. 1992; 79: 351-357Crossref PubMed Scopus (370) Google Scholar). F. nucleatum may translocate from the oral cavity to different sites in the body hematogenously and cause localized abscess or infection (6Hill G.B. Ann. Periodontol. 1998; 3: 222-232Crossref PubMed Scopus (184) Google Scholar). The organism binds to and invades different types of host cells. Attachment and invasion of epithelial and endothelial cells by F. nucleatum was observed in vitro, which elicited proinflammatory responses (7Han Y.W. Redline R.W. Li M. Yin L. Hill G.B. McCormick T.S. Infect Immun. 2004; 72: 2272-2279Crossref PubMed Scopus (284) Google Scholar, 8Han Y.W. Shi W. Huang G.T. Kinder Haake S. Park N.H. Kuramitsu H. Genco R.J. Infect Immun. 2000; 68: 3140-3146Crossref PubMed Scopus (309) Google Scholar). Attachment and invasion of endothelial cells was also observed in vivo in infected mouse placentas, leading to bacterial colonization in the placenta and resulting in adverse pregnancy outcomes (7Han Y.W. Redline R.W. Li M. Yin L. Hill G.B. McCormick T.S. Infect Immun. 2004; 72: 2272-2279Crossref PubMed Scopus (284) Google Scholar). It has been postulated that F. nucleatum may possess lectin-like and nonlectin-like adhesins for binding to various partners (9Tuttle R.S. Strubel N.A. Mourad J. Mangan D.F. Oral Microbiol. Immunol. 1992; 7: 78-83Crossref PubMed Scopus (22) Google Scholar, 10Mangan D.F. Novak M.J. Vora S.A. Mourad J. Kriger P.S. Infect. Immun. 1989; 57: 3601-3611Crossref PubMed Google Scholar, 11Shaniztki B. Ganeshkumar N. Weiss E.I. Oral Microbiol. Immunol. 1998; 13: 47-50Crossref PubMed Scopus (13) Google Scholar, 12Weiss E.I. Shaniztki B. Dotan M. Ganeshkumar N. Kolenbrander P.E. Metzger Z. Oral Microbiol. Immunol. 2000; 15: 371-377Crossref PubMed Google Scholar). Different F. nucleatum strains may bind to the same partner via different adhesins (9Tuttle R.S. Strubel N.A. Mourad J. Mangan D.F. Oral Microbiol. Immunol. 1992; 7: 78-83Crossref PubMed Scopus (22) Google Scholar). The same adhesin(s) may also be involved in binding to different partners (12Weiss E.I. Shaniztki B. Dotan M. Ganeshkumar N. Kolenbrander P.E. Metzger Z. Oral Microbiol. Immunol. 2000; 15: 371-377Crossref PubMed Google Scholar). Several putative adhesin molecules have been suggested for F. nucleatum for involvement in binding to other microbial species or human IgG (13Kinder S.A. Holt S.C. J. Bacteriol. 1993; 175: 840-850Crossref PubMed Google Scholar, 14Kaufman J. DiRienzo J.M. Infect. Immun. 1989; 57: 331-337Crossref PubMed Google Scholar, 15Shaniztki B. Hurwitz D. Smorodinsky N. Ganeshkumar N. Weiss E.I. Infect. Immun. 1997; 65: 5231-5237Crossref PubMed Google Scholar, 16Guo M. Han Y.W. Sharma A. De Nardin E. Oral Microbiol. Immunol. 2000; 15: 119-123Crossref PubMed Scopus (17) Google Scholar, 17Murray P.A. Kern D.G. Winkler J.R. Infect. Immun. 1988; 56: 1314-1319Crossref PubMed Google Scholar). However, none has been characterized, and it was not known if they were involved in bacterial binding to the host cells. A novel adhesin, FadA, from F. nucleatum 12230 was recently identified to be involved in attachment to host epithelial cells (18Han Y.W. Ikegami A. Rajanna C. Kawsar H.I. Zhou Y. Li M. Sojar H.T. Genco R.J. Kuramitsu H.K. Deng C.X. J. Bacteriol. 2005; 187: 5330-5340Crossref PubMed Scopus (138) Google Scholar). The fadA gene was highly conserved among oral fusobacterial species, including F. nucleatum, Fusobacterium periodonticum, and Fusobacterium simiae, but was absent from the nonoral fusobacteria (18Han Y.W. Ikegami A. Rajanna C. Kawsar H.I. Zhou Y. Li M. Sojar H.T. Genco R.J. Kuramitsu H.K. Deng C.X. J. Bacteriol. 2005; 187: 5330-5340Crossref PubMed Scopus (138) Google Scholar). FadA consists of 129 aa residues, with the first 18 encoding a typical signal peptide (MKKFLLLAVLAVSASAFA) (18Han Y.W. Ikegami A. Rajanna C. Kawsar H.I. Zhou Y. Li M. Sojar H.T. Genco R.J. Kuramitsu H.K. Deng C.X. J. Bacteriol. 2005; 187: 5330-5340Crossref PubMed Scopus (138) Google Scholar). It was not known, however, if the signal peptide was cleaved during secretion in F. nucleatum. Based on the amino acid sequence, FadA appeared to be predominantly α-helical. Using a novel gene disruption technique, sonoporation, we constructed the first double cross-over allelic exchange mutant of F. nucleatum, US1, carrying a deletion of fadA. Binding of US1 to the oral mucosal cell KB and Chinese hamster ovarian (CHO) 3The abbreviations used are: CHOChinese hamster ovaryPBSphosphate-buffered salineIPTGisopropyl β-d-1-thiogalactopyranosideMALDImatrix-assisted laser desorption ionizationTOFtime of flightMSmass spectrometrymFadAmature FadAmAbmonoclonal antibodyHRPhorseradish peroxidaseaaamino acid(s) 3The abbreviations used are: CHOChinese hamster ovaryPBSphosphate-buffered salineIPTGisopropyl β-d-1-thiogalactopyranosideMALDImatrix-assisted laser desorption ionizationTOFtime of flightMSmass spectrometrymFadAmature FadAmAbmonoclonal antibodyHRPhorseradish peroxidaseaaamino acid(s) cells were each reduced by 70–80% compared with the wild-type strain. Therefore, FadA was involved in binding to epithelial cells (18Han Y.W. Ikegami A. Rajanna C. Kawsar H.I. Zhou Y. Li M. Sojar H.T. Genco R.J. Kuramitsu H.K. Deng C.X. J. Bacteriol. 2005; 187: 5330-5340Crossref PubMed Scopus (138) Google Scholar). In the current study, the FadA adhesin was expressed in Escherichia coli as a His tag fusion protein, which was purified and characterized. The recombinant FadA not only attached to but also invaded the host cells as a heterogenous complex. The formation of such a complex required both the intact and secreted forms of FadA, and the complex is probably anchored in the inner membrane and protrudes through the outer membrane. Chinese hamster ovary phosphate-buffered saline isopropyl β-d-1-thiogalactopyranoside matrix-assisted laser desorption ionization time of flight mature FadA amino acid(s) Chinese hamster ovary phosphate-buffered saline isopropyl β-d-1-thiogalactopyranoside matrix-assisted laser desorption ionization time of flight mature FadA amino acid(s) and bacterial strains and used for in F. nucleatum strains were as Y.W. J. B. in Scholar). E. coli strains were in or on and at in was constructed as The fadA gene from F. nucleatum 12230 was from and tag The and sites at and the the was into at the and by into E. coli strains and or or nucleatum in the 8Han Y.W. Shi W. Huang G.T. Kinder Haake S. Park N.H. Kuramitsu H. Genco R.J. Infect Immun. 2000; 68: 3140-3146Crossref PubMed Scopus (309) Google and Y.W. Ikegami A. Rajanna C. Kawsar H.I. Zhou Y. Li M. Sojar H.T. Genco R.J. Kuramitsu H.K. Deng C.X. J. Bacteriol. 2005; 187: 5330-5340Crossref PubMed Scopus (138) Google nucleatum deletion Y.W. Ikegami A. Rajanna C. Kawsar H.I. Zhou Y. Li M. Sojar H.T. Genco R.J. Kuramitsu H.K. Deng C.X. J. Bacteriol. 2005; 187: 5330-5340Crossref PubMed Scopus (138) Google coli used for coli carrying under the on used for carrying and the carrying a fadA from F. nucleatum Y.W. Ikegami A. Rajanna C. Kawsar H.I. Zhou Y. Li M. Sojar H.T. Genco R.J. Kuramitsu H.K. Deng C.X. J. Bacteriol. 2005; 187: 5330-5340Crossref PubMed Scopus (138) Google with fadA in the and a fusion of wild-type as the in in a were purified from and at the the and the were the were into for Expression of the coli carrying or the mutant were to an of The were with isopropyl β-d-1-thiogalactopyranoside at a of for Attachment human endothelial cells oral mucosal cell KB known to be with and of human epithelial cells were as (7Han Y.W. Redline R.W. Li M. Yin L. Hill G.B. McCormick T.S. Infect Immun. 2004; 72: 2272-2279Crossref PubMed Scopus (284) Google Scholar, 8Han Y.W. Shi W. Huang G.T. Kinder Haake S. Park N.H. Kuramitsu H. Genco R.J. Infect Immun. 2000; 68: 3140-3146Crossref PubMed Scopus (309) Google Scholar, Y.W. Ikegami A. Rajanna C. Kawsar H.I. Zhou Y. Li M. Sojar H.T. Genco R.J. Kuramitsu H.K. Deng C.X. J. Bacteriol. 2005; 187: 5330-5340Crossref PubMed Scopus (138) Google Scholar). human oral cells were from J. and were as M.A. Y. Li 2000; PubMed Scopus Google Scholar). The attachment were as Y.W. Shi W. Huang G.T. Kinder Haake S. Park N.H. Kuramitsu H. Genco R.J. Infect Immun. 2000; 68: 3140-3146Crossref PubMed Scopus (309) Google Scholar, Y.W. Ikegami A. Rajanna C. Kawsar H.I. Zhou Y. Li M. Sojar H.T. Genco R.J. Kuramitsu H.K. Deng C.X. J. Bacteriol. 2005; 187: 5330-5340Crossref PubMed Scopus (138) Google Scholar). cells were into and to to The bacteria were added to the at a of infection of attachment purified mFadA or pre-FadA-mFadA complex was added to the to the of bacteria. a at under the were with phosphate-buffered saline and with It was that under the not bacterial Y.W. Shi W. Huang G.T. Kinder Haake S. Park N.H. Kuramitsu H. Genco R.J. Infect Immun. 2000; 68: 3140-3146Crossref PubMed Scopus (309) Google Scholar, Y.W. Ikegami A. Rajanna C. Kawsar H.I. Zhou Y. Li M. Sojar H.T. Genco R.J. Kuramitsu H.K. Deng C.X. J. Bacteriol. 2005; 187: 5330-5340Crossref PubMed Scopus (138) Google Scholar). were by under to for of the bacteria (7Han Y.W. Redline R.W. Li M. Yin L. Hill G.B. McCormick T.S. Infect Immun. 2004; 72: 2272-2279Crossref PubMed Scopus (284) Google Scholar, 8Han Y.W. Shi W. Huang G.T. Kinder Haake S. Park N.H. Kuramitsu H. Genco R.J. Infect Immun. 2000; 68: 3140-3146Crossref PubMed Scopus (309) Google Scholar). The bacterial were and the of attachment were expressed as the of bacteria cell to the of bacteria was in of FadA under bacterial from of was by at for in of A and at for was by and mixed with of for at The was to a of the was the was with of A and with of The was at in a with Mr of The was the of from were and from the The were and by The was used at an of in the with and a laser were mixed with an of a acid in and of the was the laser and was into the A of were for each The were and the by the The was a of A of was of were each with of mFadA in by by of FadA in each were the of mouse was at the the were from the with recombinant of the were identified by binding to FadA in by purified FadA and F. nucleatum of the was as The from was from the by the and at a of cell or were the bacterial were to Expression of the tag fusion was or or and IgG or IgG by or of in of was to a and by a The was at a of at were at or and the at was A was and from were by with and in were at were by in an a with a with an of 18 for a of The was at at for and at for to cells. The was to at for at the cell The was with in the same and at for at for at the was as the inner membrane The was and the was in and was as the outer membrane The were by mFadA in the of E. of the was through a by in the of at for was by at at for The were in of by with and at for of bacterial from of was by and in of The was at for by at for The bacterial cell was for of pre-FadA The was mixed with of in to a and mFadA was with of The was in and to the exchange with at a of The was with of to The was at for The was by of bacterial was in of A and with at for The was by at for by as The was to with acid and through the exchange as with the was with the was to The pre-FadA was and the was The was at The pre-FadA was by and in acid when The was by of mFadA or were with to the purified mFadA was mixed with at a of and at in the for The was purified by a and by of pre-FadA-mFadA mFadA was mixed with purified and pre-FadA at a of by pre-FadA into by at for at The was with an Mr of the epithelial cell binding fluorescence-labeled mFadA was used for the complex Binding of FadA to human oral cells were into a and in for the fluorescence-labeled were added and at under The cells were with The and cell were with at for and at for the nonlabeled pre-FadA-mFadA complex of in or mFadA alone in was added to the to the of the fluorescence-labeled FadA complex. The was observed under an and for time and for time and and for time The were an with binding was in the the cells were with and with at for The cells were with at for The cell and were with and at for with the were with a laser The and were used to the and and The resulting of were for by for W. of with the The fadA gene was from by into the and into E. coli The recombinant a fusion gene FadA with residues, at the a wild-type FadA fusion was identified and as A mutant was also identified and as with a at in the mature form of FadA was during and were into E. coli Expression of the recombinant fusion was with different of and by for His of tag fusion was from a with no His tag fusion was from The Mr of the recombinant fusion was and the Mr of for the intact or for the mature The of the expressed recombinant was also in wild-type tag fusion was of with The expressed appeared to be with no of on In of the FadA tag fusion was and was of with or However, the with It was only of and was not at of the expressed was no used in the each an of was each as by and by not carrying or was for attachment to host epithelial and endothelial cells of attachment to human epithelial cells, and human endothelial cells each cell the of attachment was enhanced when was the expressed tag fusion was functional and E. coli attachment to different host cells. The recombinant tag fusion was purified from E. coli the under When by a and a were in the with the and the was and to peptide and The first aa of the were the putative signal peptide. the is the form of FadA the first aa of the were of the intact form of FadA The was for the and for the as from the of the and molecules by and were with the of the mFadA and pre-FadA The of the was that the two not the was the of was with the the on the were to that no of Therefore, on two forms of FadA expressed as intact and secreted species were and were and used to the of FadA in various F. nucleatum FadA was in wild-type F. nucleatum F. nucleatum F. nucleatum F. nucleatum F. nucleatum F. nucleatum and F. nucleatum but was absent in F. nucleatum the fadA deletion mutant constructed in with the on the of fadA among oral fusobacteria and that the fadA were in different strains (18Han Y.W. Ikegami A. Rajanna C. Kawsar H.I. Zhou Y. Li M. Sojar H.T. Genco R.J. Kuramitsu H.K. Deng C.X. J. Bacteriol. 2005; 187: 5330-5340Crossref PubMed Scopus (138) Google Scholar). In an and a were from to strain. In F. nucleatum the was the whereas in F. nucleatum the was be to of FadA in different strains or to the of the for each FadA the suggested of mFadA and pre-FadA in F. nucleatum. of mFadA and pre-FadA in E. coli and F. nucleatum, was by bacterial E. coli carrying or and F. nucleatum strains 12230 and US1 were each by The were as cell The were with by The were as the inner membrane and the were as the outer membrane The recombinant mFadA and pre-FadA purified with the was as mFadA was in the cell of both E. coli and F. nucleatum but with the inner or outer membrane A and Therefore, it was probably secreted or from the bacteria but not pre-FadA, was in the of E. coli and the of mFadA secreted into with the of Pre-FadA was associated with the inner membrane and A and FadA was in the of E. coli or F. nucleatum pre-FadA in as by it with the on of A and In to the the two forms of FadA, the mFadA and pre-FadA purified the was to with a of The were and and the were at The in the in When a of of the FadA was to the FadA was in as in a and by A and that FadA formed with from to mFadA was in of pre-FadA was only in the in to mFadA with the of the complex. Therefore, pre-FadA was probably involved in formation of high Mr FadA A with FadA and was in with the high pre-FadA and mFadA were purified A and E. coli was with at for mFadA in the of the was purified the In to the of pre-FadA in the high exchange was the pre-FadA and the signal peptide two mFadA in the whereas pre-FadA was on the pre-FadA, the was first purified from cell The was to the to two The was with mFadA was Pre-FadA was with D. The pre-FadA was to and was of that pre-FadA and mFadA were each purified to a single species A and mFadA was soluble in In purified pre-FadA was only soluble under acidic neutral it was and only became soluble when mixed with mFadA at a of not mFadA was with and for binding to human oral epithelial cells. a Mr is to that of FadA, was also with and in binding by or mFadA was by When nonlabeled pre-FadA was mixed with mFadA at a of formation of high Mr was by not and binding of mFadA was observed A and The binding was by the nonlabeled pre-FadA-mFadA complex in but not by mFadA binding by the complex A and Binding by pre-FadA alone was not to its under neutral pH. However, of the nonlabeled pre-FadA with cells was by that mFadA was in the cells It is that the nonlabeled pre-FadA was also of of pre-FadA-mFadA complex into the cells. The was as in The epithelial cell were with and with The the from the through the of the at the of FadA in F. nucleatum binding to the host cells, attachment were attachment of F. nucleatum 12230 to cells was not by mFadA it in the of or of pre-FadA-mFadA complex the pre-FadA-mFadA complex a role in the attachment of F. nucleatum 12230 to the host cells. The for was and of the complex. the of the complex was the of the not be the of is the first functional of a fusobacterial adhesin in E. The was that the His tag fusion was to the of FadA and not be to FadA was expressed in F. nucleatum. in E. coli also appeared to be the The recombinant FadA enhanced the of E. coli to bind to human epithelial cells, and human endothelial cells, each by a may be involved in FadA binding to different cells. The FadA may on of different cell The was with the in binding of the fadA deletion mutant US1, when compared with the wild-type F. nucleatum. forms of recombinant FadA were the intact pre-FadA and the secreted pre-FadA mFadA on The Mr of both were with by the was not to is that the signal peptide pre-FadA to in the the of pre-FadA and mFadA may resulting in The of mFadA and pre-FadA in to the also when different or were used in it was that only one FadA species was detected. However, both species were FadA with pre-FadA of pre-FadA and mFadA by and also that the first 18 aa of the intact a signal peptide. The and secretion have recently been to be conserved in the of F. nucleatum and M. A. S.A. A. 2005; PubMed Scopus Google Scholar). Therefore, it is that FadA in fusobacteria was secreted in a as in E. The of pre-FadA and mFadA in E. coli was not an of two forms were also identified in different strains of F. nucleatum, and the of two in E. coli and F. nucleatum were with pre-FadA associated with the inner membrane and mFadA from the bacteria by or The of two forms pre-FadA is not whereas mFadA of mFadA into the by E. coli with the of The pre-FadA and mFadA each recombinant is probably to the of the His tag in the Based on the it is that to the FadA in When pre-FadA and mFadA were they formed with The of pre-FadA to mFadA with the of the Pre-FadA was absent in the that it was only required for the formation of high Mr Pre-FadA and mFadA were each purified to a single species, Binding to epithelial cells was not with mFadA However, when the same of fluorescence-labeled mFadA was mixed with pre-FadA at a of binding of mFadA was observed. The binding was in the with was observed with F. nucleatum binding to the epithelial cells Y.W. Shi W. Huang G.T. Kinder Haake S. Park N.H. Kuramitsu H. Genco R.J. Infect Immun. 2000; 68: 3140-3146Crossref PubMed Scopus (309) Google Scholar). be to of the FadA among the cells. The binding was by the nonlabeled pre-FadA-mFadA complex but not by mFadA that the of pre-FadA and mFadA not only a structural but also a functional pre-FadA is on the bacterial it an role in FadA The peptide was under and only became soluble at acidic or when mixed with is with the that pre-FadA was associated with the inner The of pre-FadA was to the high of the signal peptide. In the of of pre-FadA with mFadA may pre-FadA from It is that the signal peptide is in the inner as an for the complex. Based on the we the to its and Mr of the FadA may form a to other such as The mFadA added at the of the as they the complex it through the outer membrane. of the when the pre-FadA is added at the with its signal peptide in the inner membrane. The different of pre-FadA and mFadA observed in different F. nucleatum strains may different of the FadA and of bacterial was first observed in of J.M. S. A. PubMed Scopus Google Scholar). The is that a of have been identified to be involved in the and PubMed Scopus Google Scholar). not the of to be involved in FadA such is the which was with The of the as as the of the is under The of pre-FadA may cause of the high Mr which may be the form of of the attachment that FadA a role in F. nucleatum attachment to host cells. It is to to binding of F. nucleatum to host cells on the FadA It be however, that binding by F. nucleatum 12230 was observed in the of pre-FadA-mFadA that adhesin(s) may also on F. nucleatum. The current also that FadA was first identified as an adhesin (18Han Y.W. Ikegami A. Rajanna C. Kawsar H.I. Zhou Y. Li M. Sojar H.T. Genco R.J. Kuramitsu H.K. Deng C.X. J. Bacteriol. 2005; 187: 5330-5340Crossref PubMed Scopus (138) Google it appeared to be involved in invasion as of the epithelial cells with nonlabeled pre-FadA and was the cells. was to be to of from the it was by nonlabeled pre-FadA-mFadA complex. of the of a cell that a of was to its pre-FadA was not The of pre-FadA with cells was by it is to that pre-FadA was into the host cells as of the complex. Internalization of the pre-FadA-mFadA mFadA is an the complex is anchored in the bacterial its to the invasion of the bacteria. In mFadA be from the of mFadA may not the bacterial The of invasion is in of mFadA of the FadA and S. M. N. Han Y.W. M. PubMed Scopus Google Scholar). In E. coli as a host for functional of F. nucleatum FadA is a adhesin and in that it utilizes its own two forms for functional and attachment and invasion of the host cells.
Xu et al. (Sat,) studied this question.