February 14, 2015
The Borrelia (Lyme disease) spirochete is unique among known bacterial pathogens because it does not require iron (Fe2+) from mammals in its biochemical pathways.
The spirochete uses the NapA receptor (Dps homolog) to bind either iron or copper (Cu2+). It also uses a manganese protein transport molecule (BmtA) to bind manganese.
The presence of both the NapA receptor and the BmtA receptor is neccessary for the spirochete to colonize the midgut of the tick. But, only the manganese transport molecule is required for the spirochete to colonize the mammalian host, typically a small rodent.
In short, the spirochete needs iron or copper and manganese to infect the tick, but only manganese to infect the mammalian host (rodents, deer, humans.)