Metabolism of the Treponema
David L. Cox and Justin D. Radolf
from: Pathogenic Treponema: Molecular and Cellular Biology (Edited by: Justin D. Radolf and Sheila A. Lukehart). Caister Academic Press, U.K. (2006)
Abstract
The metabolism of the three most extensively studied treponemal species, Treponema pallidum, T. denticola, and T. phagedenis, is presented and discussed. The genomes of T. pallidum and T. denticola have been sequenced and annotated, while that that of T. phagedenis has not. The availability of these two genomic sequences allows us not only to explore potential metabolic pathways within the respective organisms but also to assess the accuracy of pre-genomic studies. In the case of T. pallidum, performance and interpretation of pre-genomic metabolic investigations were greatly complicated by the unavoidable presence of rabbit testicular contaminants in treponemal suspensions. A tabular comparison of key metabolic pathways and enzymes of T. pallidum and T. denticola (with the gene and Enzyme Commission {EC} numbers) also is presented as a reference tool. The cultivation methods for all three treponemes are discussed with emphasis on the numerous, but unsuccessful, attempts to propagate T. pallidum continuously in vitro. Finally, discoveries from genomic studies will be addressed in the context of solving the cultivation problem of T. pallidum. Although metabolically T. pallidum and T. denticola share many common pathways, they are still quite diverse in their genomic makeup. T. denticola has almost 2000 genes that are absent in T. pallidum; many of these are predicted to encode proteins with physiological functions. Three areas where the latter appears to be lacking when compared to T. denticola are (1) DNA repair and housekeeping, (2) oxygen metabolism and stress, and (3) transport capabilities read more ...
