Figure 3.
Figure 3: Models for initiation and chain elongation. a Cartoon
illustrating key points in the reaction mechanism for phi-6
polymerase. Red boxes highlight experimental results. I, apo
structure with bound Mn2+. Binding sites are identified in black
letters. II, NTP bound in site I. II|I, template bound. IV,
template bound and NTP non-productively bound at site I. V,
initial productive binding at site P. VI, template ratchets
back. VII, second GTP bound at site P. Polymerization can occur.
VIII, polymerization has occurred, releasing nascent duplex from
ordered binding at the active site C. The C-terminal domain
moves allowing the duplex to ratchet forward, out of the active
site. b, 6
polymerase and polymerases of the Reoviridae family in the
context of the viral capsid. Polymerases are coloured yellow. In
the Reoviridae panel the helicase is orange, and the 5' end of
the positive strand is attached to the polymerase, holding the
genome segment, ready to facilitate re-initiation.
The above figure is reprinted
by permission from Macmillan Publishers Ltd:
Nature
(2001,
410,
235-240)
copyright 2001.
6
polymerase. Red boxes highlight experimental results. I, apo
structure with bound Mn2+. Binding sites are identified in black
letters. II, NTP bound in site I. II|I, template bound. IV,
template bound and NTP non-productively bound at site I. V,
initial productive binding at site P. VI, template ratchets
back. VII, second GTP bound at site P. Polymerization can occur.
VIII, polymerization has occurred, releasing nascent duplex from
ordered binding at the active site C. The C-terminal domain
moves allowing the duplex to ratchet forward, out of the active
site. b, 
6
polymerase and polymerases of the Reoviridae family in the
context of the viral capsid. Polymerases are coloured yellow. In
the Reoviridae panel the helicase is orange, and the 5' end of
the positive strand is attached to the polymerase, holding the
genome segment, ready to facilitate re-initiation.