The<i>Haemophilus influenzae</i>Hia autotransporter harbours two adhesive pockets that reside in the passenger domain and recognize the same host cell receptor

Laarmann, Sven; Cutter, David; Juehne, Twyla; Barenkamp, Stephen J.; Geme, Joseph W. St.

doi:10.1046/j.1365-2958.2002.03189.x

Cited by 70 publications

(79 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Three heparin binding domains exist in the N terminus and the C terminus of the vitronectin molecule (Fig. 5A) (19,28). To further investigate the nature of the interaction of vitronectin to H. influenzae, a series of blocking experiments with heparin was performed.…”

Section: Hsf-vitronectin Interaction Is Inhibited By Heparinmentioning

confidence: 99%

“…Vitronectin plays a major role in the complement cascade by inhibiting the MAC of complement (19). To analyze the importance of Hsf in H. influenzae survival when exposed to NHS, the wildtype strains RM804 and Eagan, in addition to the corresponding mutants, were tested in a serum bactericidal assay.…”

Section: Hsf Is Crucial For H Influenzae Survival In Human Serummentioning

confidence: 99%

“…Hsf is found as short, thin surface fibrils at the bacterial surface and is associated with adherence to epithelial cells (16). In 25% of all unencapsulated strains, a homologue to the Hsf protein, H. influenzae adhesin (Hia), can be found (17)(18)(19). The hia gene, which is shorter than the hsf gene, encodes for a protein with a size of 1098 aa and harbors only one domain that corresponds to the three repetitive domains in Hsf.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Haemophilus influenzae Surface Fibrils Contribute to Serum Resistance by Interacting with Vitronectin

Hallström

Trajkovska

Forsgren

et al. 2006

The Journal of Immunology

View full text Add to dashboard Cite

Vitronectin inhibits the membrane attack complex of the complement system and is found both in plasma and the extracellular matrix. In this study, we have identified the outer membrane protein Haemophilus surface fibrils (Hsf) as the major vitronectin-binding protein in encapsulated H. influenzae type b. A H. influenzae mutant devoid of Hsf showed a significantly decreased binding to both soluble and immobilized vitronectin as compared with the wild-type counterpart. Moreover, Escherichia coli-expressing Hsf at the surface strongly adhered to immobilized vitronectin. Importantly, the H. influenzae Hsf mutant had a markedly reduced survival as compared with the wild-type bacterium when incubated with normal human serum. A series of truncated Hsf fragments were recombinantly manufactured in E. coli. The vitronectin binding regions were located within two separate binding domains. In conclusion, Hsf interacts with vitronectin and thereby inhibits the complement-mediated bactericidal activity, and thus is a major H. influenzae virulence factor.

show abstract

Section: Hsf-vitronectin Interaction Is Inhibited By Heparinmentioning

confidence: 99%

Section: Hsf Is Crucial For H Influenzae Survival In Human Serummentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Haemophilus influenzae Surface Fibrils Contribute to Serum Resistance by Interacting with Vitronectin

Hallström

Trajkovska

Forsgren

et al. 2006

The Journal of Immunology

View full text Add to dashboard Cite

show abstract

“…Hia is an autotransporter that mediates adherence to cultured epithelial cells via two distinct binding domains contained within residues 50-252 and 580-714, and it has a translocator domain contained within residues 1,023-1,098 (40)(41)(42)(43). Whole-cell sonicates and trichloroacetic acid-precipitated supernatant proteins generated from DH5␣ expressing either Hia or the HMW1-Hia chimeric protein in the presence of HMW1B were examined by immunoblot analysis.…”

Section: Hmw1b Interacts With the N-terminal Fragment Of Hmw1mentioning

confidence: 99%

Evidence for conservation of architecture and physical properties of Omp85-like proteins throughout evolution

Surana

Grass

Hardy

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Omp85-like proteins represent a family of proteins involved in protein translocation, and they are present in all domains of life, except archaea. In eukaryotes, Omp85-like proteins have been demonstrated to form tetrameric pore-forming complexes that interact directly with their substrate proteins. Studies performed with bacterial Omp85-like proteins have demonstrated pore-forming activity but no evidence of multimerization. In this article, we characterize the Haemophilus influenzae HMW1B protein, an Omp85-like protein that has been demonstrated to be critical for secretion of the H. influenzae HMW1 adhesin. Analysis of purified protein by biochemical and electron microscopic techniques revealed that HMW1B forms a tetramer. Examination using liposomeswelling assays demonstrated that HMW1B has pore-forming activity, with a pore size of Ϸ2.7 nm. Far-Western blot analysis established that HMW1B interacts with the N terminus of HMW1. These results provide evidence that a bacterial Omp85-like protein forms a tetramer and interacts directly with a substrate protein, suggesting that the architecture and physical properties of Omp85-like proteins have been conserved throughout evolution. O mp85-like proteins represent a large family defined by phylogenetic relatedness, secondary-structure predictions, and a role in protein translocation (1-5). Members of this family are present in diverse organisms across the evolutionary spectrum, including bacteria, fungi, plants, and animals (1, 4). The widespread nature of Omp85-like proteins underscores their critical role in cellular processes, highlighted by the fact that many are required for cell viability (3,4,(6)(7)(8)(9). Although all Omp85-like proteins share sequence homology, they can be grouped into two classes based on the specific role that they play in protein translocation. One class is typified by Saccharomyces cerevisiae Sam50 and Neurospora crassa Tob55, which are chiefly involved in insertion of ␤-barrel proteins into the outer membrane (OM) of mitochondria (6, 9). The second class is epitomized by the chloroplast protein Toc75, which is involved in secretion of proteins across a membrane (10, 11). Interestingly, both classes of Omp85-like proteins are present in Gramnegative bacteria. Neisseria meningitidis Omp85, the namesake of this family of proteins, has been demonstrated recently to be critical for the insertion of proteins into the bacterial OM (7). Other Gram-negative bacterial Omp85-like proteins, including Serratia marcescens ShlB and Bordetella pertussis FhaC [and other members of the so-called two-partner secretion (TPS) pathway], have been demonstrated to function in protein export across the OM (12).The high level of amino acid homology among Omp85-like proteins from bacteria to humans raises the possibility that members of this family have similar structures. Although no crystal structures exist so far for Omp85-like proteins, several of these proteins have been subjected to biochemical studies of overall architecture. In eukaryotes, both classes...

show abstract

“…We considered the possibility that the high affinity of ScpB for iFn might be based solely upon the ScpB-PDF binding site or upon the presence of multiple lower-affinity Fn-binding sites on ScpB in addition to Scp-PDF. Of note, a previous study of the Hia adhesin of Haemophilus influenzae demonstrated that two lower-affinity binding pockets on the same molecule can interact to create a higher-avidity interaction (16). To distinguish between these possibilities, we determined the affinity of ScpB-PDF for iFn using SPR.…”

Section: Resultsmentioning

confidence: 99%

High-Affinity Interaction between Fibronectin and the Group B Streptococcal C5a Peptidase Is Unaffected by a Naturally Occurring Four-Amino-Acid Deletion That Eliminates Peptidase Activity

Tamura¹,

Hull

Oberg³

et al. 2006

Infect Immun

View full text Add to dashboard Cite

The streptococcal C5a peptidase (ScpB) of group B streptococci (GBS) is found in virtually all clinical GBS isolates and is required for mucosal colonization in a neonatal mouse model. ScpB inhibits neutrophil chemotaxis by enzymatically cleaving the complement component C5a. We previously identified a second function of ScpB as a fibronectin (Fn) adhesin using phage display. However, phage display can identify low-affinity interactions. We therefore measured the affinity of both full-length recombinant ScpB (FL-ScpB) and the 110-amino-acid phage display fragment (Scp-PDF) for immobilized Fn using surface plasmon resonance. The affinity for Fn was very high for both FL-ScpB (equilibrium dissociation constant [K D ] ‫؍‬ 4.0 nM) and Scp-PDF (K D ‫؍‬ 4.4 nM) and is consistent with a biologically significant role for the adhesin activity of ScpB. We also studied the Fn adhesin activity of a common natural variant of ScpB (ScpB⌬) that contains a 4-amino-acid deletion that eliminates peptidase activity. The integrity of scpB is otherwise maintained, suggesting that the Fn adhesin activity of ScpB may be responsible for its conservation in these strains. The affinities of both FL-ScpB⌬ (K D ‫؍‬ 2.4 nM) and ScpB⌬-PDF (K D ‫؍‬ 1.4 nM) for Fn are unaffected by the deletion. Complementation in trans by both scpB and scpB⌬ corrected the Fn-binding defect of an scpB deletion mutant GBS strain to an identical degree. The high affinity of ScpB for Fn and the maintenance of this affinity in ScpB⌬ support our hypothesis that the Fn adhesin activity of scpB plays a role in virulence.Group B streptococci (GBS) are a leading cause of sepsis and meningitis in newborns (2) and an emerging cause of serious bacterial infections in immunocompromised adults and the elderly (12). Recent advances in prevention have significantly reduced the burden of early-onset neonatal disease (onset at Ͻ7 days of age) but have not had an impact on the incidence of late-onset disease (onset at 7 to 90 days of age) (25).Evasion of host defenses is a key component of bacterial virulence. One major host defense is complement, which is involved in a variety of functions including opsonization and chemotaxis. Complement activation results in the proteolytic cleavage of C5 to generate C5a. C5a is a potent chemotactic factor that plays an important role in recruiting neutrophils to sites of inflammation. The streptococcal C5a peptidase (ScpB) is a cell surface endopeptidase produced by GBS that inactivates C5a (9). The role of scpB in pulmonary disease by GBS was recently investigated (7). Isogenic scpB mutant GBS strains showed a 5-log decrease in their ability to colonize the lungs of adult mice, demonstrating that scpB plays a significant role in mucosal colonization. These results suggested that the ability to cleave C5a is required for mucosal colonization.However, epidemiologic studies of clinical isolates of GBS called into question the role of the peptidase activity of ScpB in virulence. The scpB gene is conserved among clinical isolates, suggesting tha...

show abstract

TheHaemophilus influenzaeHia autotransporter harbours two adhesive pockets that reside in the passenger domain and recognize the same host cell receptor

Cited by 70 publications

References 35 publications

Haemophilus influenzae Surface Fibrils Contribute to Serum Resistance by Interacting with Vitronectin

Haemophilus influenzae Surface Fibrils Contribute to Serum Resistance by Interacting with Vitronectin

Evidence for conservation of architecture and physical properties of Omp85-like proteins throughout evolution

High-Affinity Interaction between Fibronectin and the Group B Streptococcal C5a Peptidase Is Unaffected by a Naturally Occurring Four-Amino-Acid Deletion That Eliminates Peptidase Activity

Contact Info

Product

Resources

About