title: Interaction of the Lyme disease spirochete with its tick vector.
abstract: Borrelia burgdorferi, the causative agent of Lyme disease (along with closely related genospecies), is in the deeply branching spirochete phylum. The bacterium is maintained in nature in an enzootic cycle that involves transmission from a tick vector to a vertebrate host and acquisition from a vertebrate host to a tick vector. During its arthropod sojourn, B. burgdorferi faces a variety of stresses, including nutrient deprivation. Here, we review some of the spirochetal factors that promote persistence, maintenance and dissemination of B. burgdorferi in the tick, and then focus on the utilization of available carbohydrates as well as the exquisite regulatory systems invoked to adapt to the austere environment between blood meals and to signal species transitions as the bacteria traverse their enzootic cycle. The spirochetes shift their source of carbon and energy from glucose in the vertebrate to glycerol in the tick. Regulation of survival under limiting nutrients requires the classic stringent response in which RelBbu controls the levels of the alarmones guanosine tetraphosphate and guanosine pentaphosphate (collectively termed (p)ppGpp), while regulation at the tick-vertebrate interface as well as regulation of protective responses to the blood meal require the two-component system Hk1/Rrp1 to activate production of the second messenger cyclic-dimeric-GMP (c-di-GMP).
authors.affiliation: Departments of Medicine, Pediatrics, and Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA.
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Caimano
authors.affiliation: Division of Biological Sciences, University of Montana, Missoula, MT, USA.
authors.forename: Dan
authors.initials: D
authors.lastname: Drecktrah
authors.affiliation: Department of Veterinary Medicine, University of Maryland-College Park and Virginia-Maryland Regional College of Veterinary Medicine, College Park, MD, USA.
authors.forename: Faith
authors.initials: F
authors.lastname: Kung
authors.affiliation: Division of Biological Sciences, University of Montana, Missoula, MT, USA.|Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, MT, USA.
authors.forename: D Scott
authors.initials: DS
authors.lastname: Samuels
mesh_terms: D000818:Animals; D001096:Arachnid Vectors / Q000382:microbiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D025065:Borrelia burgdorferi / Q000472:pathogenicity / Q000502:physiology*; D002244:Carbon / Q000378:metabolism; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006158:Guanosine Pentaphosphate / Q000378:metabolism; D054884:Host-Pathogen Interactions; D008193:Lyme Disease / Q000382:microbiology*; D013987:Ticks / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; D006158:Guanosine Pentaphosphate; C062025:bis(3',5')-cyclic diguanylic acid; D002244:Carbon; D006152:Cyclic GMP