Figure 3.

(Color online) Proposed evolution of bacterial NAD kinase from ATP/poly(P)-NAD kinase to ATP-NAD kinase.⁶²⁾ The changes in GGDG motifs of NAD kinases from GGDGT via GGDGS into GGDGN and those in corresponding codons from ACT/C (Thr) via AGT/C (Ser) into AAT/C (Asn) during bacterial evolution are indicated by arrows, together with related Gram-positive and -negative bacteria. ATP/poly(P)-NAD kinase carrying the GGDGT motif, in which the Thr residue is encoded by ACT/C, but not by ACA/G, is assumed to be a direct ancestor of γ-proteobacterial ATP-NAD kinases carrying the GGDGN motif, in which Asn is encoded by AAT/C. ATP/poly(P)-NAD kinases carrying the GGDGM motif (in which the Met residue is encoded by ATG), which is concentrated within Gram-positive bacteria, is not a direct ancestor of γ-proteobacterial ATP-NAD kinases. This figure was reproduced from Y. Nakamichi et al. (2013) Sci. Rep. 3, 2632 (Ref. 62, Supporting information) with some modifications.