In:
PLOS Pathogens, Public Library of Science (PLoS), Vol. 17, No. 11 ( 2021-11-9), p. e1010051-
Abstract:
Complement proteins can form membrane attack complex (MAC) pores that directly kill Gram-negative bacteria. MAC pores assemble by stepwise binding of C5b, C6, C7, C8 and finally C9, which can polymerize into a transmembrane ring of up to 18 C9 monomers. It is still unclear if the assembly of a polymeric-C9 ring is necessary to sufficiently damage the bacterial cell envelope to kill bacteria. In this paper, polymerization of C9 was prevented without affecting binding of C9 to C5b-8, by locking the first transmembrane helix domain of C9. Using this system, we show that polymerization of C9 strongly enhanced damage to both the bacterial outer and inner membrane, resulting in more rapid killing of several Escherichia coli and Klebsiella strains in serum. By comparing binding of wildtype and ‘locked’ C9 by flow cytometry, we also show that polymerization of C9 is impaired when the amount of available C9 per C5b-8 is limited. This suggests that an excess of C9 is required to efficiently form polymeric-C9. Finally, we show that polymerization of C9 was impaired on complement-resistant E . coli strains that survive killing by MAC pores. This suggests that these bacteria can specifically block polymerization of C9. All tested complement-resistant E . coli expressed LPS O-antigen (O-Ag), compared to only one out of four complement-sensitive E . coli . By restoring O-Ag expression in an O-Ag negative strain, we show that the O-Ag impairs polymerization of C9 and results in complement-resistance. Altogether, these insights are important to understand how MAC pores kill bacteria and how bacterial pathogens can resist MAC-dependent killing.
Type of Medium:
Online Resource
ISSN:
1553-7374
DOI:
10.1371/journal.ppat.1010051
DOI:
10.1371/journal.ppat.1010051.g001
DOI:
10.1371/journal.ppat.1010051.g002
DOI:
10.1371/journal.ppat.1010051.g003
DOI:
10.1371/journal.ppat.1010051.g004
DOI:
10.1371/journal.ppat.1010051.g005
DOI:
10.1371/journal.ppat.1010051.g006
DOI:
10.1371/journal.ppat.1010051.g007
DOI:
10.1371/journal.ppat.1010051.s001
DOI:
10.1371/journal.ppat.1010051.s002
DOI:
10.1371/journal.ppat.1010051.s003
DOI:
10.1371/journal.ppat.1010051.s004
DOI:
10.1371/journal.ppat.1010051.s005
DOI:
10.1371/journal.ppat.1010051.s006
DOI:
10.1371/journal.ppat.1010051.s007
DOI:
10.1371/journal.ppat.1010051.s008
DOI:
10.1371/journal.ppat.1010051.r001
DOI:
10.1371/journal.ppat.1010051.r002
DOI:
10.1371/journal.ppat.1010051.r003
DOI:
10.1371/journal.ppat.1010051.r004
Language:
English
Publisher:
Public Library of Science (PLoS)
Publication Date:
2021
detail.hit.zdb_id:
2205412-1