Multiple active centers of multi-subunit RNA polymerases
نویسندگان
چکیده
The active center of multi-subunit RNA polymerase consists of two modules, the Mg(2+) module, holding the catalytic Mg(2+) ion, and a module made of a flexible domain, the Trigger Loop. Uniquely, the TL module can be substituted by alternative modules, thus changing the catalytic properties of the active center.
منابع مشابه
Metal A and Metal B Sites of Nuclear RNA Polymerases Pol IV and Pol V Are Required for siRNA-Dependent DNA Methylation and Gene Silencing
Plants are unique among eukaryotes in having five multi-subunit nuclear RNA polymerases: the ubiquitous RNA polymerases I, II and III plus two plant-specific activities, nuclear RNA polymerases IV and V (previously known as Polymerases IVa and IVb). Pol IV and Pol V are not required for viability but play non-redundant roles in small interfering RNA (siRNA)-mediated pathways, including a pathwa...
متن کاملShared active site architecture between archaeal PolD and multi-subunit RNA polymerases revealed by X-ray crystallography
Archaeal replicative DNA polymerase D (PolD) constitute an atypical class of DNA polymerases made of a proofreading exonuclease subunit (DP1) and a larger polymerase catalytic subunit (DP2), both with unknown structures. We have determined the crystal structures of Pyrococcus abyssi DP1 and DP2 at 2.5 and 2.2 Å resolution, respectively, revealing a catalytic core strikingly different from all o...
متن کاملNTP-driven translocation and regulation of downstream template opening by multi-subunit RNA polymerases.
Multi-subunit RNA polymerases bind nucleotide triphosphate (NTP) substrates in the pretranslocated state and carry the dNMP-NTP base pair into the active site for phosphoryl transfer. NTP-driven translocation requires that NTP substrates enter the main-enzyme channel before loading into the active site. Based on this model, a new view of fidelity and efficiency of RNA synthesis is proposed. The...
متن کاملCo-expression of multiple subunits enables recombinant SNAPC assembly and function for transcription by human RNA polymerases II and III.
Human small nuclear (sn) RNA genes are transcribed by either RNA polymerase II or III depending upon the arrangement of their core promoter elements. Regardless of polymerase specificity, these genes share a requirement for a general transcription factor called the snRNA activating protein complex or SNAP(C). This multi-subunit complex recognizes the proximal sequence element (PSE) commonly fou...
متن کاملAncient RNA stems that terminate transcription
Multi-subunit RNA polymerases are the enzymes that perform transcription in all living organisms and that have emerged before the divergence of domains of life. The structures of catalytic cores and their functions during elongation step of transcription cycle are very similar for all multi-subunit RNA polymerases. In contrast, the mechanisms for terminating the RNA synthesis have seemingly div...
متن کامل