H8-L-H9 conformation in non-proteobacterial GluRSs: [<<t] conformation
The α-[>>t ] conformation ofEco -GluRSs were then compared with seven non-proteobacterial H8-L -H9 conformations. As shown in Figure 5F, the central HGD(Q/A) sequence signature is absent in all non-proteobacterial H8-L -H9 motifs. In five cases – BBU(ND), MTU(ND), EMG(D+), TMA(T2) and TTH(D+) – there is an insertion of E/D between G and D in the HGD(Q/A) Type II’ β-turn motif. For TEL(ND) there is a two-residue (EG) insertion, while the loop length in TMA(T1) is identical toEco -GluRS. Upon superposition of the eight non-proteobacterial H8-L -H9 conformations onto the corresponding α-[>>t ] conformation ofEco -GluRS (Figure 4C), it was found that except MTU(ND) and BBU(ND) that are discussed below, all showed a loop conformation that faced away from tRNA. As opposed to the [>>t ] conformation, the “facing away from tRNA” conformation is termed as the[<<t]conformation.