Defining targets for complement components C4b and C3b on the pathogenic neisseriae
Authors
Lewis, Lisa A.Ram, Sanjay
Prasad, Alpana
Gulati, Sunita
Getzlaff, Silke
Blom, Anna M.
Vogel, Ulrich
Rice, Peter A.
UMass Chan Affiliations
Division of Infectious Diseases and ImmunologyDocument Type
Journal ArticlePublication Date
2007-11-07Keywords
Bacterial Outer Membrane ProteinsComplement C3b
Complement C4b
Humans
Neisseria gonorrhoeae
Neisseria meningitidis
Porins
Protein Binding
Protein Isoforms
Life Sciences
Medicine and Health Sciences
Metadata
Show full item recordAbstract
Complement is a key arm of the innate immune defenses against the pathogenic neisseriae. We previously identified lipooligosaccharide on Neisseria meningitidis as an acceptor for complement C4b. Little is known about other neisserial targets for complement proteins C3 and C4, which covalently attach to bacterial surfaces and initiate opsonization and killing. In this study we demonstrate that Neisseria gonorrhoeae porin (Por) 1B selectively binds C4b via amide linkages and C3b via ester linkages. Using strains expressing hybrid Por1A/1B molecules, a region spanned by loops 4 and 5 of Por1B was identified as the preferred binding site for C4b. We also identified the opacity protein (Opa), a major adhesin of pathogenic neisseriae, as a target for C4b and C3b on both N. meningitidis and N. gonorrhoeae. Using N. gonorrhoeae variants that predominantly expressed individual Opa proteins, we found that all Opa proteins tested (A, B, C, D, E, F, and I) bound C4b and C3b via amide and ester linkages, respectively. Amide linkages with Por1B and Opa were confirmed using serum containing only the C4A isoform, which exclusively forms amide linkages with targets. While monomers and heterodimers of C4Ab were detected on bacterial targets, C4Bb appeared to preferentially participate in heterodimer (C5 convertase) formation. Our data provide another explanation for the enhanced serum sensitivity of Por1B-bearing gonococci. The binding of C3b and C4b to Opa provides a rationale for the recovery of predominantly "transparent" (Opa-negative) neisserial isolates from persons with invasive disease, where the bacteria encounter high levels of complement.Source
Infect Immun. 2008 Jan;76(1):339-50. Epub 2007 Nov 5. Link to article on publisher's siteDOI
10.1128/IAI.00613-07Permanent Link to this Item
http://hdl.handle.net/20.500.14038/38397PubMed ID
17984207Related Resources
Link to Article in PubMedae974a485f413a2113503eed53cd6c53
10.1128/IAI.00613-07