Dataset Information

Multigene expression in vivo: supremacy of large versus small terminators for T7 RNA polymerase.

ABSTRACT: Designing and building multigene constructs is commonplace in synthetic biology. Yet functional successes at first attempts are rare because the genetic parts are not fully modular. In order to improve the modularity of transcription, we previously showed that transcription termination in vitro by bacteriophage T7 RNA polymerase could be made more efficient by substituting the standard, single, T? large (class I) terminator with adjacent copies of the vesicular stomatitis virus (VSV) small (class II) terminator. However, in vitro termination at the downstream VSV terminator was less efficient than at the upstream VSV terminator, and multigene overexpression in vivo was complicated by unexpectedly inefficient VSV termination within Escherichia coli cells. Here, we address hypotheses raised in that study by showing that VSV or preproparathyroid hormone (PTH) small terminators spaced further apart can work independently (i.e., more efficiently) in vitro, and that VSV and PTH terminations are severely inhibited in vivo. Surprisingly, the difference between class II terminator function in vivo versus in vitro is not due to differences in plasmid supercoiling, as supercoiling had a minimal effect on termination in vitro. We therefore turned to T? terminators for "BioBrick" synthesis of a pentameric gene construct suitable for overexpression in vivo. This indeed enabled coordinated overexpression and copurification of five His-tagged proteins using the first construct attempted, indicating that this strategy is more modular than other strategies. An application of this multigene overexpression and protein copurification method is demonstrated by supplying five of the six E. coli translation factors required for reconstitution of translation from a single cell line via copurification, greatly simplifying the reconstitution.

SUBMITTER: Du L

PROVIDER: S-EPMC3312007 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Multigene expression in vivo: supremacy of large versus small terminators for T7 RNA polymerase.

Du Liping L Villarreal Seth S Forster Anthony C AC

Biotechnology and bioengineering 20111201 4

Designing and building multigene constructs is commonplace in synthetic biology. Yet functional successes at first attempts are rare because the genetic parts are not fully modular. In order to improve the modularity of transcription, we previously showed that transcription termination in vitro by bacteriophage T7 RNA polymerase could be made more efficient by substituting the standard, single, TΦ large (class I) terminator with adjacent copies of the vesicular stomatitis virus (VSV) small (clas ...[more]

PMID: 22094962

Similar Datasets

Project description:Intrinsic terminators, which encode GC-rich RNA hairpins followed immediately by a 7-to-9-nucleotide (nt) U-rich "U-tract," play principal roles of punctuating and regulating transcription in most bacteria. However, canonical intrinsic terminators with strong U-tracts are underrepresented in some bacterial lineages, notably mycobacteria, leading to proposals that their RNA polymerases stop at noncanonical intrinsic terminators encoding various RNA structures lacking U-tracts. We generated recombinant forms of mycobacterial RNA polymerase and its major elongation factors NusA and NusG to characterize mycobacterial intrinsic termination. Using in vitro transcription assays devoid of possible mycobacterial contaminants, we established that mycobacterial RNA polymerase terminates more efficiently than Escherichia coli RNA polymerase at canonical terminators with imperfect U-tracts but does not terminate at putative terminators lacking U-tracts even in the presence of mycobacterial NusA and NusG. However, mycobacterial NusG exhibits a novel termination-stimulating activity that may allow intrinsic terminators with suboptimal U-tracts to function efficiently. IMPORTANCE Bacteria rely on transcription termination to define and regulate units of gene expression. In most bacteria, precise termination and much regulation by attenuation are accomplished by intrinsic terminators that encode GC-rich hairpins and U-tracts necessary to disrupt stable transcription elongation complexes. Thus, the apparent dearth of canonical intrinsic terminators with recognizable U-tracts in mycobacteria is of significant interest both because noncanonical intrinsic terminators could reveal novel routes to destabilize transcription complexes and because accurate understanding of termination is crucial for strategies to combat mycobacterial diseases and for computational bioinformatics generally. Our finding that mycobacterial RNA polymerase requires U-tracts for intrinsic termination, which can be aided by NusG, will guide future study of mycobacterial transcription and aid improvement of predictive algorithms to annotate bacterial genome sequences.

Dataset Information

Multigene expression in vivo: supremacy of large versus small terminators for T7 RNA polymerase.

Publications

Multigene expression in vivo: supremacy of large versus small terminators for T7 RNA polymerase.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets