Crystal structure of the membrane attack complex assembly inhibitor BGA71 from the Lyme disease agent Borrelia bavariensis

Kalvis Brangulis, Inara Akopjana, Ivars Petrovskis, Andris Kazaks, Peter Kraiczy, Kaspars Tars

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
8 Downloads (Pure)


Borrelia (B.) bavariensis, B. burgdorferi, B. afzelii, B. garinii, B. spielmanii, and B. mayonii are the causative agents in Lyme disease. Lyme disease spirochetes reside in infected Ixodes ticks and are transferred to mammalian hosts during tick feeding. Once transmitted, spirochetes must overcome the first line of defense of the innate immune system either by binding complement regulators or by terminating the formation of the membrane attack complex (MAC). In B. bavariensis, the proteins BGA66 and BGA71 inhibit complement activation by interacting with the late complement components C7, C8, and C9, as well as with the formed MAC. In this study, we have determined the crystal structure of the potent MAC inhibitor BGA71 at 2.9 Ǻ resolution. The structure revealed a cysteine cross-linked homodimer. Based on the crystal structure of BGA71 and the structure-based sequence alignment with CspA from B. burgdorferi, we have proposed a potential binding site for C7 and C9, both of which are constituents of the formed MAC. Our results shed light on the molecular mechanism of immune evasion developed by the human pathogenic Borrelia species to overcome innate immunity. These results will aid in the understanding of Lyme disease pathogenesis and pave the way for the development of new strategies to prevent Lyme disease.

Original languageEnglish
Article number11286
JournalScientific Reports
Issue number1
Publication statusPublished - 1 Dec 2018

Field of Science*

  • 1.6 Biological sciences
  • 3.3 Health sciences

Publication Type*

  • 1.1. Scientific article indexed in Web of Science and/or Scopus database


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