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Tick Sugar Influence on Cell Wall of Borrelia Spirochetes

Persistent Borrelia burgdorferi
Borrelia burgdorferi spirochete in mouse, Photo by Stephen W. Barthold, DVM, PhD

Nature Microbiology recently published an article where researchers identified a sugar that influences cell wall function in Borrelia spirochetes. Authors state that Borrelia burgdorferi bacteria produces glycan chains in the cell wall where MurNAc is occasionally replaced with an unknown sugar. Investigators identified that B. burgdorferi produces glycans that contain GlcNAc–GlcNAc. Chitobiose is the unusual disaccharide, or sugar, identified in the cell wall of Borrelia bacteria.

Mutant bacteria, bacteria that require a particular additional nutrient which the normal strain does not, have altered morphology, reduced motility, and cell envelope defects that researchers suspect result from producing peptidoglycan that is stiffer than that in wild-type bacteria.

Virginia Tech researchers discovered that the bacterium that causes Lyme disease has a highly unusual modification in its protective molecular bag—its peptidoglycan, which is common to all bacteria. Researchers conducted LCMS, liquid chromatography coupled with mass spectroscopy to determine that chitobiose was the actual sugar. They also conducted Nuclear Magnetic Resonance and metabolic labeling studies with C13 labeled sugars to confirm this finding. They additionally determined why this modification is found in Borrelia—it allows for elasticity which supports effective motility of the bacteria to move through tissue and cartilage. Without this modification, motility is impeded.

The change in the Borrelia bacterium is unprecedented—it’s an unusual sugar modification that is not known to occur in any other organism. One way the bacterium gets this sugar modification is from ticks. This happens by absorbing a carbohydrate unique to ticks. The alteration is specific to ticks and allows the bacterium to better move and be more likely to cause disease in hosts.

Researchers provide evidence for this model, demonstrating that bacteria that are unable to bring in chitobiose to the cells have reduced amounts of peptidoglycan, as well as altered peptidoglycan composition, which results in abnormalities in bacterial cell form and structure.

The significance of these findings is that disrupting the balance between flagellar motion and peptidoglycan structure impairs motility, which hinders bacterial movement. This finding could potentially shed light on understanding what causes symptoms and illness in humans, as well as identifying potential diagnostic and treatment strategies that target Borrelia spirochetes. 

Read the full text Nature Microbiology article here

Read additional LDA articles on Borrelia here