Figure 4.
Figure 4 Structure of tRNAtyr compared with that of tRNA^ser.
(A) Comparison of the secondary structures of T.thermophilus
tRNA^tyr(G A)
(left) and tRNA^tyr(GGA) (right), highlighting differences,
conserved in other prokaryotic organisms, that determine the
orientation of the long variable arm. tRNA^tyr nucleotides with
only backbone contacts to TyrRSTT are shown in purple, those
with only base contacts are shown in green and those with
backbone and base contacts are shown in orange. (B) Comparison
of the 3D structures of the base of the long variable arm in
T.thermophilus tRNA^tyr and T.thermophilus tRNA^ser (Biou et
al., 1994), based on the structural alignment in (C). In
tRNA^ser, Gua-20B is unpaired and stacks against the first base
pair of the long variable arm, which comprises A45:U48-1 (top).
In tRNA^tyr, U48-1 is unpaired and stacks against the first base
pair of the long variable arm, which comprises A20B:U48−2
(bottom). (C) View looking down the anticodon stem-loop of the
structural alignment of tRNA^tyr (blue) and tRNA^ser (red) based
on superposition of 46 phosphates from the acceptor stem, D- and
T-loops (r.m.s.d. = 1.16 Å). The tRNA cores have a very
similar structure, but the variable arms project at an angle
differing by 50°.
A)
(left) and tRNA^tyr(GGA) (right), highlighting differences,
conserved in other prokaryotic organisms, that determine the
orientation of the long variable arm. tRNA^tyr nucleotides with
only backbone contacts to TyrRSTT are shown in purple, those
with only base contacts are shown in green and those with
backbone and base contacts are shown in orange. (B) Comparison
of the 3D structures of the base of the long variable arm in
T.thermophilus tRNA^tyr and T.thermophilus tRNA^ser (Biou et
al., 1994), based on the structural alignment in (C). In
tRNA^ser, Gua-20B is unpaired and stacks against the first base
pair of the long variable arm, which comprises A45:U48-1 (top).
In tRNA^tyr, U48-1 is unpaired and stacks against the first base
pair of the long variable arm, which comprises A20B:U48−2
(bottom). (C) View looking down the anticodon stem-loop of the
structural alignment of tRNA^tyr (blue) and tRNA^ser (red) based
on superposition of 46 phosphates from the acceptor stem, D- and
T-loops (r.m.s.d. = 1.16 Å). The tRNA cores have a very
similar structure, but the variable arms project at an angle
differing by 
50°.