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Nikolay Zenkin

About Nikolay Zenkin:
No description specified

SEEK ID: https://fairdomhub.org/people/344

Location:  United Kingdom

Expertise: Biochemistry, Molecular Biology

Tools: Molecular biology techniques (RNA/DNA/Protein), in vivo crosslinking, in vitro transcription, protein purification, phage techniques

ORCID: Not specified

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Project positions

Noisy-Strep (University of Newcastle)

Related items

Noisy-Strep

Bistable switches are the key elements of the regulatory networks governing cell development, differentiation and life-strategy decisions. Transcriptional noise is a main determinant that causes switching between different states in bistable systems. By using the human pathogen Streptococcus pneumoniae as a model bacterium, we will investigate how transcriptional fidelity and processivity influence (noisy) gene expression and participate in bistability. To study this question, we will use both
...

Programme: SysMO

Public web page: http://www.sysmo.net/index.php?index=163

Investigation of bacterial transcription fidelity and processivity
Noisy-Strep
No description specified

Person responsible: Nikolay Zenkin

Snapshots: No snapshots

Kinetics of misincorporation and proofreading by bacterial RNA polymerase
Noisy-Strep

Artificial transcription elongation compexes are assembled in vitro using synthetic deoxy-oligonucleotides (representing template and non template DNA strands), radiolabelled RNA (representing nascent transcript) and purified RNA polymerase. After high salt wash the incorrect NTP is added and reaction is allowed to proceed for the various amounts of time. Reaction is stopped by addition of formamide-containing loading solution and the products are resolved on high-percentage denaturing polyacryamide
...

Submitter: Nikolay Zenkin

Assay type: Reactomics

Technology type: Enzymatic Activity Measurements

Snapshots: No snapshots

Control of transcription elongation by GreA determines rate of gene expression in Streptococcus pneumoniae
Noisy-Strep

Abstract (Expand)

Transcription by RNA polymerase may be interrupted by pauses caused by backtracking or misincorporation that can be resolved by the conserved bacterial Gre-factors. However, the consequences of such … pausing in the living cell remain obscure. Here, we developed molecular biology and transcriptome sequencing tools in the human pathogen Streptococcus pneumoniae and provide evidence that transcription elongation is rate-limiting on highly expressed genes. Our results suggest that transcription elongation may be a highly regulated step of gene expression in S. pneumoniae. Regulation is accomplished via long-living elongation pauses and their resolution by elongation factor GreA. Interestingly, mathematical modeling indicates that long-living pauses cause queuing of RNA polymerases, which results in 'transcription traffic jams' on the gene and thus blocks its expression. Together, our results suggest that long-living pauses and RNA polymerase queues caused by them are a major problem on highly expressed genes and are detrimental for cell viability. The major and possibly sole function of GreA in S. pneumoniae is to prevent formation of backtracked elongation complexes.

Authors: , , M. Herber, L. Attaiech, , , S. Klumpp, ,

Date Published: 6th Sep 2014

Publication Type: Not specified

Multiple active centers of multi-subunit RNA polymerases
Noisy-Strep

Abstract (Expand)

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.

Authors: , Mohammad Roghanian,

Date Published: 10th Jul 2012

Publication Type: Not specified

Hypothesis: emergence of translation as a result of RNA helicase evolution
Noisy-Strep

Abstract (Expand)

The origin of translation and the genetic code is one of the major mysteries of evolution. The advantage of templated protein synthesis could have been achieved only when the translation apparatus had … already become very complex. This means that the translation machinery, as we know it today, must have evolved towards some different essential function that subsequently sub-functionalised into templated protein synthesis. The hypothesis presented here proposes that translation originated as the result of evolution of a primordial RNA helicase, which has been essential for preventing dying out of the RNA organism in sterile double-stranded form. This hypothesis emerges because modern ribosome possesses RNA helicase activity that likely dates back to the RNA world. I hypothesise that codon-anticodon interactions of tRNAs with mRNA evolved as a mechanism used by RNA helicase, the predecessor of ribosomes, to melt RNA duplexes. In this scenario, peptide bond formation emerged to drive unidirectional movement of the helicase via a molecular ratchet mechanism powered by Brownian motion. I propose that protein synthesis appeared as a side product of helicase activity. The first templates for protein synthesis were functional RNAs (ribozymes) that were unwound by the helicase, and the first synthesised proteins were of random or non-sense sequence. I further suggest that genetic code emerged to avoid this randomness. The initial genetic code thus emerged as an assignment of amino acids to codons according to the sequences of the pre-existing RNAs to take advantage of the side products of RNA helicase function.

Editor:

Date Published: 28th Apr 2012

Publication Type: Not specified

In vitro experimental system for analysis of transcription-translation coupling
Noisy-Strep

Abstract (Expand)

Transcription and translation are coupled in bacteria, meaning that translation takes place co-transcriptionally. During transcription-translation, both machineries mutually affect each others' … functions, which is important for regulation of gene expression. Analysis of interactions between RNA polymerase (RNAP) and the ribosome, however, are limited due to the lack of an in vitro experimental system. Here, we report the development of an in vitro transcription coupled to translation system assembled from purified components. The system allows controlled stepwise transcription and simultaneous stepwise translation of the nascent RNA, and permits investigation of the interactions of RNAP with the ribosome, as well as the effects of translation on transcription and transcription on translation. As an example of usage of this experimental system, we uncover complex effects of transcription-translation coupling on pausing of transcription.

Authors: Daniel Castro-Roa,

Date Published: 3rd Jan 2012

Publication Type: Not specified

Factor-independent transcription pausing caused by recognition of the RNA-DNA hybrid sequence
Noisy-Strep

Abstract (Expand)

Pausing of transcription is an important step of regulation of gene expression in bacteria and eukaryotes. Here we uncover a factor-independent mechanism of transcription pausing, which is determined … by the ability of the elongating RNA polymerase to recognize the sequence of the RNA-DNA hybrid. We show that, independently of thermodynamic stability of the elongation complex, RNA polymerase directly 'senses' the shape and/or identity of base pairs of the RNA-DNA hybrid. Recognition of the RNA-DNA hybrid sequence delays translocation by RNA polymerase, and thus slows down the nucleotide addition cycle through 'in pathway' mechanism. We show that this phenomenon is conserved among bacterial and eukaryotic RNA polymerases, and is involved in regulatory pauses, such as a pause regulating the production of virulence factors in some bacteria and a pause regulating transcription/replication of HIV-1. The results indicate that recognition of RNA-DNA hybrid sequence by multi-subunit RNA polymerases is involved in transcription regulation and may determine the overall rate of transcription elongation.

Authors: Aleksandra Bochkareva, , Vasisht R Tadigotla,

Date Published: 29th Nov 2011

Publication Type: Not specified

A new basal promoter element recognized by RNA polymerase core enzyme
Noisy-Strep

Abstract (Expand)

Bacterial promoters are recognized by RNA polymerase (RNAP) σ subunit, which specifically interacts with the -10 and -35 promoter elements. Here, we provide evidence that the β' zipper, an … evolutionarily conserved loop of the largest subunit of RNAP core, interacts with promoter spacer, a DNA segment that separates the -10 and -35 promoter elements, and facilitates the formation of stable closed promoter complex. Depending on the spacer sequence, the proposed interaction of the β' zipper with the spacer can also facilitate open promoter complex formation and even substitute for interactions of the σ subunit with the -35 element. These results suggest that there exists a novel class of promoters that rely on interaction of the β' zipper with promoter spacer, along with or instead of interactions of σ subunit with the -35 element, for their activity. Finally, our data suggest that sequence-dependent interactions of the β' zipper with DNA can contribute to promoter-proximal σ-dependent RNAP pausing, a recently recognized important step of transcription control.

Authors: , Vasisht R Tadigotla, Konstantin Severinov,

Date Published: 26th Jul 2011

Publication Type: Not specified

Controlled interplay between trigger loop and Gre factor in the RNA polymerase active centre
Noisy-Strep

Abstract (Expand)

The highly processive transcription by multi-subunit RNA polymerases (RNAP) can be interrupted by misincorporation or backtracking events that may stall transcription or lead to erroneous transcripts. … Backtracked/misincorporated complexes can be resolved via hydrolysis of the transcript. Here, we show that, in response to misincorporation and/or backtracking, the catalytic domain of RNAP active centre, the trigger loop (TL), is substituted by transcription factor Gre. This substitution turns off the intrinsic TL-dependent hydrolytic activity of RNAP active centre, and exchanges it to a far more efficient Gre-dependent mechanism of RNA hydrolysis. Replacement of the TL by Gre factor occurs only in backtracked/misincorporated complexes, and not in correctly elongating complexes. This controlled switching of RNAP activities allows the processivity of elongation to be unaffected by the hydrolytic activity of Gre, while ensuring efficient proofreading of transcription and resolution of backtracked complexes.

Authors: Mohammad Roghanian, ,

Date Published: 27th Jan 2011

Publication Type: Not specified

Central role of the RNA polymerase trigger loop in intrinsic RNA hydrolysis
Noisy-Strep

Abstract (Expand)

The active center of RNA polymerase can hydrolyze phosphodiester bonds in nascent RNA, a reaction thought to be important for proofreading of transcription. The reaction proceeds via a general two … Mg(2+) mechanism and is assisted by the 3' end nucleotide of the transcript. Here, by using Thermus aquaticus RNA polymerase, we show that the reaction also requires the flexible domain of the active center, the trigger loop (TL). We show that the invariant histidine (beta' His1242) of the TL is essential for hydrolysis/proofreading and participates in the reaction in two distinct ways: by positioning the 3' end nucleotide of the transcript that assists catalysis and/or by directly participating in the reaction as a general base. We also show that participation of the beta' His1242 of the TL in phosphodiester bond hydrolysis does not depend on the extent of elongation complex backtracking. We obtained similar results with Escherichia coli RNA polymerase, indicating that the function of the TL in phosphodiester bond hydrolysis is conserved among bacteria.

Authors: Yulia Yuzenkova,

Date Published: 1st Jun 2010

Publication Type: Not specified

Stepwise mechanism for transcription fidelity
Noisy-Strep

Abstract (Expand)

Transcription is the first step of gene expression and is characterized by a high fidelity of RNA synthesis. During transcription, the RNA polymerase active centre discriminates against not just … non-complementary ribo NTP substrates but also against complementary 2'- and 3'-deoxy NTPs. A flexible domain of the RNA polymerase active centre, the Trigger Loop, was shown to play an important role in this process, but the mechanisms of this participation remained elusive.

Authors: , Aleksandra Bochkareva, Vasisht R Tadigotla, Mohammad Roghanian, Savva Zorov, Konstantin Severinov,

Date Published: 1st Apr 2010

Publication Type: Not specified

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