: The complete sequence of the Treponema pallidum subsp. pallidum genome was determined in 1998 providing a new window to the physiology of this enigmatic organism. Availability of the annotated sequence represents a major advance in syphilis research. However, sequence information can only serve to predict function, and functional analysis is a necessary step in the practical application of this data to syphilis prevention and control. This application represents a reactivation of a project aimed at determining the nutritional and environmenta requirements of T. pallidum and applying this information toward the in vitro culture and improve understanding of the pathogenesis of syphilis. Specific Aim 1 will focus on the metabolic pathways predicted b, the sequence and the application of this information to the in vitro culture of T. pallidum. Both cell-free and tissue-culture systems will be utilized to assess the effects of medium components on T. pallidum survival multiplication, and DNA replication and damage. Specific Aim 2 will address the relationship between 7 pallidum and oxygen, which is key to its survival and growth. The central hypothesis addressed in this Aim i that NADH oxidase and the multimeric protein AhpC play a major role both in maintaining a proper red-o' environment in the cell and in removing reactive oxygen intermediates. In Specific Aim 3, Dr. Milton Saier an colleagues at the University of California at San Diego will examine the role of the phosphoenolpyruvate dependent phospho-transferase system (PTS) in gene regulation. A unique aspect of the T. pallidum genome i that it encodes HPr (PtsH), the HPr(ser) kinase (PtsK), a frameshifted Enzyme I (PtsI) and two additiona potential regulatory PTS proteins, but no recognizable sugar-specific PTS permeases. The likelihood that the existing PTS components are involved in a regulatory network independent of transport function will b investigated. It is anticipated that the results of this study will improve understanding of the growth requirements, oxygen utilization, and regulatory systems of T. pallidum.