Figure 1.

Growth curves for wild-type M. smegmatis mc²155 cells (blue) or alr mutant TAM23 cells (red) treated (A) without D-alanine or (B) with 50 mM D-alanine, respectively. Growth curves were collected in triplicate and the error bars were calculated using SEM. (C) Mean specific activities (µmoles of substrate consumed per min per mg protein) in M. smegmatis cell extracts. Data are as described previously by Chacon et al. 2002.¹¹ Cells were grown to mid-exponential phase, harvested, and lysed. Cell-free extracts were assayed for Alr activity in triplicate. A bovine serum albumin (BSA) control was prepared at the same protein concentration as the cell extracts and assayed in triplicate. All error bars were calculated using standard deviations. (D) Intracellular steady-state concentrations of amino acids L- and D- alanine in mc²155 (black) and TAM23 (grey). Data reproduced from Chacon et al. 2009.¹⁰