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. Author manuscript; available in PMC: 2018 Jul 20.
Published in final edited form as: Enzymes. 2017 Apr 12;41:89–115. doi: 10.1016/bs.enz.2017.03.003

Fig. 4.

Fig. 4

G37 in TrmD and in the tRNA anticodon stem–loop structure. (A) G37 binding to TrmD organizes the flexible linker of chain B (magenta) and projects G36 to the trefoil knot of chain A (cyan) to stabilize the entire tRNA molecule bound to the enzyme (PDB: 4YVI). (B) The unmethylated G37 in the anticodon stem–loop (ASL) structure of tRNAPro/CGG (G37–ASL) prevents the interaction between U32 and A38 and renders the 5′-side of the ASL disordered and invisible (left, PDB: 4P70). The methylated m1G37 remodels the ASL structure (m1G37–ASL) to allow U32–A38 base pairing as in a canonical structure (middle, PDB: 4LT8). The insertion of G37.5 to the ASL, resulting in the structure of m1G37-[ASL + G37.5], disrupts U32–A38 pairing to form the aberrant U32–G37.5 pairing in a disordered structure (right, PDB: 4L47) similar to that in the G37–ASL structure.