T7 RNA Polymerase: Difference between revisions
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'''Positioning of the +1 base in the active site'''. Melting of a bubble within the DNA allows the (single stranded) template strand to enter the active site, and allows template strand bases +1 and +2 to orient in the active site, poised for initiation. | '''Positioning of the +1 base in the active site'''. Melting of a bubble within the DNA allows the (single stranded) template strand to enter the active site, and allows template strand bases +1 and +2 to orient in the active site, poised for initiation. | ||
'''Catalysis'''. The enzyme then binds the first two substrate NTP's, as directed by the template (typically two GTP's, encoded by CC in the template strand). A phosphoryl transfer reaction occurs to form the product dinucleotide (pppGpG). | '''Catalysis'''. The enzyme then <scene name='77/778917/T7rp_gg_bound/1'>binds the first two substrate NTP's</scene>, as directed by the template (typically two GTP's, encoded by CC in the template strand). A phosphoryl transfer reaction occurs to form the product dinucleotide (pppGpG). | ||
'''Movement'''. At this point, the complex is in the pre-translocated state and to add the next base, the enzyme must translocate forward along the DNA (or equivalently, the RNA/DNA slides backwards), forming the post-translocated state. In the latter state (only) the active site now accommodates binding of the next NTP to the (+3) template base. | '''Movement'''. At this point, the complex is in the pre-translocated state and to add the next base, the enzyme must translocate forward along the DNA (or equivalently, the RNA/DNA slides backwards), forming the post-translocated state. In the latter state (only) the active site now accommodates binding of the next NTP to the (+3) template base. | ||
