Dukan Diet

Lyme Spirochete Binds to Heparan in Blood Vessels

Borrelia burgdorferi Sticks to Host Cells via Heparin-binding Proteins

A research group at the University of Calgary has watched the binding of fluorescent Borrelia burgdorferi spirochetes, the Lyme disease pathogen, to the surface of blood vessels in mice. (ref. below) A small heparin molecule was shown to block this interaction between the spirochete surface protein BBK32 and the heparan sulfate proteoglycans of the endothelial cells of the skin blood vessels.

The heparin-binding domains in the spirochete protein, BBK32 are easy to spot in the amino acid sequence of this protein that I downloaded from the NCBI protein database:

>gi|19072701|gb|AAL84596.1| BBK32 [Borrelia burgdorferi]
MKKVKSKYLALGLLFGFISCDLFIRYEMKEESPGLFDKGNSILET
SEESIKKPMNKKGKKIARKKGKSKVSRKEPYIHSLKRDSANKSN
FLQKNVILEEESLKTELLKEQSETRKEKIQKQQDEYKGMTQGSL
NSLSGESGELKETIESNEIDITIDSDLRPKSSLQDIAGSNSISYTDE
IEEEDYARYYLDEDDEDDEYYEDDYEEIRLSNRYQSYLEGVKYNV
DSAINTINKIYDTYTLFSTKLTQMYSTRLDNLAKAKAKEEAAKFTK
EDLEKNFKTLLNYIQVSVKTAANFVYINDTHAKRKLENIEAEIKTL
IAKIKEQSNLYEAYKAIVTSILLMRDSLKEVQGIIDKNGVWY
Basic amino acids are K=lysine, R=arginine

The minimal heparin binding pairs, e.g. KKVKSK are shown in red and the strong heparin-binding triplets, e.g. KRK, are shown in blue. Notice that one triplet is augmented with several pairs to further enhance heparin binding.

I would also expect that BBK32 would be internalized into host cells and transported into the nucleus, where it may alter transcription, a la HIV-TAT. The existence of multiple, strong heparin-binding domains may also serve to bind the BBK32 (or the spirochetes) to multiple different heparan sulfate proteoglycans and interfere with the HSPG circulation system. This may have a toxic effect.

reference:
Norman MU, Moriarty TJ, Dresser AR, Millen B, Kubes P, Chaconas G. Molecular mechanisms involved in vascular interactions of the Lyme disease pathogen in a living host. PLoS Pathog. 2008 Oct 3;4(10):e1000169.