The Mycobacterium tuberculosis (Mtb) F1Fo-ATP synthase (alpha(3):beta(3):gamma:epsilon:a:b:b':c(9)) is an essential enzyme that supplies energy for both the aerobic growing and the hypoxic dormant stage of the mycobacterial life cycle. Employing the heterologous F-ATP synthase model system alpha(chi)(3):beta(3):gamma we showed previously, that transfer of the C-terminal domain (CTD) of Mtb subunit alpha (Mt(alpha 51-549)) to a standard F-ATP synthase a subunit suppresses ATPase activity. Here we determined the 3D reconstruction from electron micrographs of the alpha(chi)(3):beta(3):gamma complex reconstituted with the Mtb subunit epsilon (Mt epsilon), which has been shown to crosstalk with the CTD of Mt alpha. Together with the first solution shape of Mtb subunit alpha (Mt alpha), derived from solution X-ray scattering, the structural data visualize the extended C-terminal stretch of the mycobacterial subunit alpha. In addition, Mt epsilon mutants Mt epsilon R62L, Mt epsilon E87A, Mt epsilon(6-121), and Mt epsilon(1-120), reconstituted with alpha(chi)(3):beta(3):gamma provided insight into their role in coupling and in trapping inhibiting MgADP. NMR solution studies of Mt epsilon E87A gave insights into how this residue contributes to stability and crosstalk between the N-terminal domain (NTD) and the CTD of Mt epsilon. Analyses of the N-terminal mutant MI epsilon(6-121) highlight the differences of the NTD of mycobacterial subunit e to the well described Geobacillul stearothermophilus or Escherichia coli counterparts. These data are discussed in context of a crosstalk between the very N-terminal amino acids of Mt epsilon and the loop region of one c subunit of the c-ring turbine for coupling of proton-translocation and ATP synthesis activity.