scholarly journals Direct observation of processive exoribonuclease motion using optical tweezers

2015 ◽  
Vol 112 (49) ◽  
pp. 15101-15106 ◽  
Author(s):  
Furqan M. Fazal ◽  
Daniel J. Koslover ◽  
Ben F. Luisi ◽  
Steven M. Block
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Optical Tweezers ◽  
Single Molecule ◽  
Rna Binding ◽  
Polynucleotide Phosphorylase ◽  
Rnase R ◽  
Binding Domains ◽  
Inchworm Mechanism ◽  
Periodogram Analysis

Bacterial RNases catalyze the turnover of RNA and are essential for gene expression and quality surveillance of transcripts. In Escherichia coli, the exoribonucleases RNase R and polynucleotide phosphorylase (PNPase) play critical roles in degrading RNA. Here, we developed an optical-trapping assay to monitor the translocation of individual enzymes along RNA-based substrates. Single-molecule records of motion reveal RNase R to be highly processive: one molecule can unwind over 500 bp of a structured substrate. However, enzyme progress is interrupted by pausing and stalling events that can slow degradation in a sequence-dependent fashion. We found that the distance traveled by PNPase through structured RNA is dependent on the A+U content of the substrate and that removal of its KH and S1 RNA-binding domains can reduce enzyme processivity without affecting the velocity. By a periodogram analysis of single-molecule records, we establish that PNPase takes discrete steps of six or seven nucleotides. These findings, in combination with previous structural and biochemical data, support an asymmetric inchworm mechanism for PNPase motion. The assay developed here for RNase R and PNPase is well suited to studies of other exonucleases and helicases.

scholarly journals The Role of RNA-Binding Proteins in Vertebrate Neural Crest and Craniofacial Development

2021 ◽  
Vol 9 (3) ◽  
pp. 34
Author(s):  
Thomas E. Forman ◽  
Brenna J. C. Dennison ◽  
Katherine A. Fantauzzo
Keyword(s):  
Gene Expression ◽  
Neural Crest ◽  
Binding Proteins ◽  
Rna Binding ◽  
Gene Expression Regulation ◽  
Rna Binding Proteins ◽  
Craniofacial Development ◽  
Specific Sequence ◽  
Altered Expression ◽  
Binding Domains

Cranial neural crest (NC) cells delaminate from the neural folds in the forebrain to the hindbrain during mammalian embryogenesis and migrate into the frontonasal prominence and pharyngeal arches. These cells generate the bone and cartilage of the frontonasal skeleton, among other diverse derivatives. RNA-binding proteins (RBPs) have emerged as critical regulators of NC and craniofacial development in mammals. Conventional RBPs bind to specific sequence and/or structural motifs in a target RNA via one or more RNA-binding domains to regulate multiple aspects of RNA metabolism and ultimately affect gene expression. In this review, we discuss the roles of RBPs other than core spliceosome components during human and mouse NC and craniofacial development. Where applicable, we review data on these same RBPs from additional vertebrate species, including chicken, Xenopus and zebrafish models. Knockdown or ablation of several RBPs discussed here results in altered expression of transcripts encoding components of developmental signaling pathways, as well as reduced cell proliferation and/or increased cell death, indicating that these are common mechanisms contributing to the observed phenotypes. The study of these proteins offers a relatively untapped opportunity to provide significant insight into the mechanisms underlying gene expression regulation during craniofacial morphogenesis.

scholarly journals Visualizing the translation and packaging of HIV-1 full-length RNA

2020 ◽  
Vol 117 (11) ◽  
pp. 6145-6155 ◽  
Author(s):  
Jianbo Chen ◽  
Yang Liu ◽  
Bin Wu ◽  
Olga A. Nikolaitchik ◽  
Preeti R. Mohan ◽  
...  
Keyword(s):  
Gene Expression ◽  
Single Molecule ◽  
Rna Binding ◽  
Virus Assembly ◽  
Full Length ◽  
Rna Molecules ◽  
Rna Translation ◽  
Translation Template ◽  
A Genome ◽  
Hiv 1

HIV-1 full-length RNA (HIV-1 RNA) plays a central role in viral replication, serving as a template for Gag/Gag-Pol translation and as a genome for the progeny virion. To gain a better understanding of the regulatory mechanisms of HIV-1 replication, we adapted a recently described system to visualize and track translation from individual HIV-1 RNA molecules in living cells. We found that, on average, half of the cytoplasmic HIV-1 RNAs are being actively translated at a given time. Furthermore, translating and nontranslating RNAs are well mixed in the cytoplasm; thus, Gag biogenesis occurs throughout the cytoplasm without being constrained to particular subcellular locations. Gag is an RNA binding protein that selects and packages HIV-1 RNA during virus assembly. A long-standing question in HIV-1 gene expression is whether Gag modulates HIV-1 RNA translation. We observed that despite its RNA-binding ability, Gag expression does not alter the proportion of translating HIV-1 RNA. Using single-molecule tracking, we found that both translating and nontranslating RNAs exhibit dynamic cytoplasmic movement and can reach the plasma membrane, the major HIV-1 assembly site. However, Gag selectively packages nontranslating RNA into the assembly complex. These studies illustrate that although HIV-1 RNA serves two functions, as a translation template and as a viral genome, individual RNA molecules carry out only one function at a time. These studies shed light on previously unknown aspects of HIV-1 gene expression and regulation.

scholarly journals KH domain containing RNA-binding proteins coordinate with microRNAs to regulate Caenorhabditis elegans development

2021 ◽  
Vol 11 (2) ◽  
Author(s):  
Dustin Haskell ◽  
Anna Zinovyeva
Keyword(s):  
Gene Expression ◽  
Caenorhabditis Elegans ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Regulate Gene Expression ◽  
C Elegans ◽  
Binding Domains ◽  
Kh Domain ◽  
Regulate Gene

Abstract MicroRNAs (miRNAs) and RNA-binding proteins (RBPs) regulate gene expression at the post-transcriptional level, but the extent to which these key regulators of gene expression coordinate their activities and the precise mechanisms of this coordination are not well understood. RBPs often have recognizable RNA binding domains that correlate with specific protein function. Recently, several RBPs containing K homology (KH) RNA binding domains were shown to work with miRNAs to regulate gene expression, raising the possibility that KH domains may be important for coordinating with miRNA pathways in gene expression regulation. To ascertain whether additional KH domain proteins functionally interact with miRNAs during Caenorhabditis elegans development, we knocked down twenty-four genes encoding KH-domain proteins in several miRNA sensitized genetic backgrounds. Here, we report that a majority of the KH domain-containing genes genetically interact with multiple miRNAs and Argonaute alg-1. Interestingly, two KH domain genes, predicted splicing factors sfa-1 and asd-2, genetically interacted with all of the miRNA mutants tested, whereas other KH domain genes showed genetic interactions only with specific miRNAs. Our domain architecture and phylogenetic relationship analyses of the C. elegans KH domain-containing proteins revealed potential groups that may share both structure and function. Collectively, we show that many C. elegans KH domain RBPs functionally interact with miRNAs, suggesting direct or indirect coordination between these two classes of post-transcriptional gene expression regulators.

scholarly journals The RNA-binding protein Hfq assembles into foci-like structures in nitrogen starved Escherichia coli

2020 ◽  
Vol 295 (35) ◽  
pp. 12355-12367
Author(s):  
Josh McQuail ◽  
Amy Switzer ◽  
Lynn Burchell ◽  
Sivaramesh Wigneshweraraj
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Adaptive Response ◽  
Rna Binding ◽  
Nitrogen Starvation ◽  
Binding Protein ◽  
Regulatory Protein ◽  
Rna Binding Protein ◽  
E Coli

The initial adaptive responses to nutrient depletion in bacteria often occur at the level of gene expression. Hfq is an RNA-binding protein present in diverse bacterial lineages that contributes to many different aspects of RNA metabolism during gene expression. Using photoactivated localization microscopy and single-molecule tracking, we demonstrate that Hfq forms a distinct and reversible focus-like structure in Escherichia coli specifically experiencing long-term nitrogen starvation. Using the ability of T7 phage to replicate in nitrogen-starved bacteria as a biological probe of E. coli cell function during nitrogen starvation, we demonstrate that Hfq foci have a role in the adaptive response of E. coli to long-term nitrogen starvation. We further show that Hfq foci formation does not depend on gene expression once nitrogen starvation has set in and occurs indepen-dently of the transcription factor N-regulatory protein C, which activates the initial adaptive response to N starvation in E. coli. These results serve as a paradigm to demonstrate that bacterial adaptation to long-term nutrient starvation can be spatiotemporally coordinated and can occur independently of de novo gene expression during starvation.

scholarly journals Single-molecule observation of DNA compaction by meiotic protein SYCP3

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Johanna L Syrjänen ◽  
Iddo Heller ◽  
Andrea Candelli ◽  
Owen R Davies ◽  
Erwin J G Peterman ◽  
...  
Keyword(s):  
Optical Tweezers ◽  
Single Molecule ◽  
Critical Role ◽  
Chromosomal Dna ◽  
Lateral Element ◽  
Structural Characterisation ◽  
Chromosome Architecture ◽  
Dna Binding Domains ◽  
Meiotic Progression ◽  
Binding Domains

In a previous paper (Syrjänen et al., 2014), we reported the first structural characterisation of a synaptonemal complex (SC) protein, SYCP3, which led us to propose a model for its role in chromosome compaction during meiosis. As a component of the SC lateral element, SYCP3 has a critical role in defining the specific chromosome architecture required for correct meiotic progression. In the model, the reported compaction of chromosomal DNA caused by SYCP3 would result from its ability to bridge distant sites on a DNA molecule with the DNA-binding domains located at each end of its strut-like structure. Here, we describe a single-molecule assay based on optical tweezers, fluorescence microscopy and microfluidics that, in combination with bulk biochemical data, provides direct visual evidence for our proposed mechanism of SYCP3-mediated chromosome organisation.

scholarly journals Defining the Domains of Human Polynucleotide Phosphorylase (hPNPaseOLD-35) Mediating Cellular Senescence

2005 ◽  
Vol 25 (16) ◽  
pp. 7333-7343 ◽  
Author(s):  
Devanand Sarkar ◽  
Eun Sook Park ◽  
Luni Emdad ◽  
Aaron Randolph ◽  
Kristoffer Valerie ◽  
...  
Keyword(s):  
Cellular Senescence ◽  
Deletion Mutant ◽  
Rna Binding ◽  
Mitochondrial Protein ◽  
Terminal Differentiation ◽  
Human Melanoma ◽  
Polynucleotide Phosphorylase ◽  
Binding Domains ◽  
Evolutionarily Conserved ◽  
Rna Binding Domains

ABSTRACT To fully comprehend cellular senescence, identification of relevant genes involved in this process is mandatory. Human polynucleotide phosphorylase (hPNPaseOLD-35), an evolutionarily conserved 3′, 5′ exoribonuclease mediating mRNA degradation, was first identified as a predominantly mitochondrial protein overexpressed during terminal differentiation and senescence. Overexpression of hPNPaseOLD-35 in human melanoma cells and melanocytes induces distinctive changes associated with senescence, potentially mediated by direct degradation of c-myc mRNA by this enzyme. hPNPaseOLD-35 contains two RNase PH (RPH) domains, one PNPase domain, and two RNA binding domains. Using deletion mutation analysis in combination with biochemical and molecular analyses we now demonstrate that the presence of either one of the two RPH domains conferred similar functional activity as the full-length protein, whereas a deletion mutant containing only the RNA binding domains was devoid of activity. Moreover, either one of the two RPH domains induced the morphological, biochemical, and gene expression changes associated with senescence, including degradation of c-myc mRNA. Subcellular distribution confirmed hPNPaseOLD-35 to be localized both in mitochondria and the cytoplasm. The present study elucidates how a predominantly mitochondrial protein, via its localization in both mitochondria and cytoplasm, is able to target a specific cytoplasmic mRNA, c-myc, for degradation and through this process induce cellular senescence.

scholarly journals Single-molecule analysis reveals two separate DNA-binding domains in the Escherichia coli UvrA dimer

2009 ◽  
Vol 37 (6) ◽  
pp. 1962-1972 ◽  
Author(s):  
Koen Wagner ◽  
Geri Moolenaar ◽  
John van Noort ◽  
Nora Goosen
Keyword(s):  
Escherichia Coli ◽  
Dna Binding ◽  
Single Molecule ◽  
Dna Binding Domains ◽  
Binding Domains ◽  
Single Molecule Analysis

scholarly journals KH domain containing RNA-binding proteins coordinate with microRNAs to regulate Caenorhabditis elegans development

2020 ◽  
Author(s):  
D Haskell ◽  
A Zinovyeva
Keyword(s):  
Gene Expression ◽  
Caenorhabditis Elegans ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Regulate Gene Expression ◽  
C Elegans ◽  
Binding Domains ◽  
Kh Domain ◽  
Regulate Gene

ABSTRACTmicroRNAs (miRNAs) and RNA binding proteins (RBPs) regulate gene expression at the post-transcriptional level, but the extent to which these key regulators of gene expression coordinate and the precise mechanisms of their coordination are not well understood. RNA binding proteins often have recognizable RNA binding domains that correlate with specific protein function. Recently, several RBPs containing K Homology (KH) RNA binding domains were shown to work with miRNAs to regulate gene expression, raising the possibility that KH domains may be important for coordinating with miRNA pathways in gene expression regulation. To ascertain whether additional KH domain proteins functionally interact with miRNAs during Caenorhabditis elegans development, we knocked down twenty-four genes encoding KH-domain proteins in several miRNA sensitized genetic backgrounds. Here, we report that a majority of the KH domain-containing genes genetically interact with multiple miRNAs and Argonaute alg-1. Interestingly, two KH domain genes, predicted splicing factors sfa-1 and asd-2, genetically interacted with all of the miRNA mutants tested, while other KH domain genes exhibited functional interactions only with specific miRNAs. Our domain architecture and phylogenetic relationship analyses of the C. elegans KH domain-containing proteins revealed potential groups that may share both structure and function. Collectively, we show that many C. elegans KH domain RBPs functionally interact with miRNAs, suggesting direct or indirect coordination between these two classes of post-transcriptional gene expression regulators.

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