1
|
Carico C, Placzek WJ. Reviewing PTBP1 Domain Modularity in the Pre-Genomic Era: A Foundation to Guide the Next Generation of Exploring PTBP1 Structure-Function Relationships. Int J Mol Sci 2023; 24:11218. [PMID: 37446395 DOI: 10.3390/ijms241311218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 06/28/2023] [Accepted: 07/06/2023] [Indexed: 07/15/2023] Open
Abstract
Polypyrimidine tract binding protein 1 (PTBP1) is one of the most well-described RNA binding proteins, known initially for its role as a splicing repressor before later studies revealed its numerous roles in RNA maturation, stability, and translation. While PTBP1's various biological roles have been well-described, it remains unclear how its four RNA recognition motif (RRM) domains coordinate these functions. The early PTBP1 literature saw extensive effort placed in detailing structures of each of PTBP1's RRMs, as well as their individual RNA sequence and structure preferences. However, limitations in high-throughput and high-resolution genomic approaches (i.e., next-generation sequencing had not yet been developed) precluded the functional translation of these findings into a mechanistic understanding of each RRM's contribution to overall PTBP1 function. With the emergence of new technologies, it is now feasible to begin elucidating the individual contributions of each RRM to PTBP1 biological functions. Here, we review all the known literature describing the apo and RNA bound structures of each of PTBP1's RRMs, as well as the emerging literature describing the dependence of specific RNA processing events on individual RRM domains. Our goal is to provide a framework of the structure-function context upon which to facilitate the interpretation of future studies interrogating the dynamics of PTBP1 function.
Collapse
Affiliation(s)
- Christine Carico
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - William J Placzek
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| |
Collapse
|
2
|
Han Z, Wu Z, Gong W, Zhou W, Chen L, Li C. Allosteric mechanism for SL RNA recognition by polypyrimidine tract binding protein RRM1: An atomistic MD simulation and network-based study. Int J Biol Macromol 2022; 221:763-772. [PMID: 36058398 DOI: 10.1016/j.ijbiomac.2022.08.181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/20/2022] [Accepted: 08/27/2022] [Indexed: 12/01/2022]
Abstract
Polypyrimidine tract-binding protein (PTB), an RNA-binding protein, is involved in the regulation of diverse processes in mRNA metabolism. However, the allosteric modulation of its binding with RNA remains unclear. We explore the dynamic characteristics of PTB RNA recognition motif 1 (RRM1) in its RNA-free and wild-type/mutant RNA-bound states to understand the issues using molecular dynamics (MD) simulation, perturbation response scanning (PRS) and protein structure network (PSN) models. It is found that RNA binding strengthens RRM1 stability, while L151G mutation in α3 helix far away from the interface makes the complex unstable. The latter is caused by long-distance dynamic couplings, which makes intermolecular electrostatic and entropy energies unfavorable. The weakened couplings between interface β sheets and C-terminal parts upon mutation reveal RNA recognition is co-regulated by these regions. Interestingly, PRS analysis reveals the allostery caused by the perturbation on α3 helix has already been pre-encoded in the equilibrium dynamics of the protein structure. PSN analysis shows the details of the allosteric signal transmission, revealing the necessity of strong couplings between α3 helix and interface for maintaining the high binding affinity. This study sheds light on the mechanisms of PTB allostery and RNA recognition and can provide important information for drug design.
Collapse
Affiliation(s)
- Zhongjie Han
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China
| | - Zhixiang Wu
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China
| | - Weikang Gong
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China
| | - Wenxue Zhou
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China
| | - Lei Chen
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China
| | - Chunhua Li
- Faculty of Environmental and Life Sciences, Beijing University of Technology, Beijing 100124, China.
| |
Collapse
|
3
|
Levintov L, Vashisth H. Role of salt-bridging interactions in recognition of viral RNA by arginine-rich peptides. Biophys J 2021; 120:5060-5073. [PMID: 34710377 PMCID: PMC8633718 DOI: 10.1016/j.bpj.2021.10.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 08/17/2021] [Accepted: 10/06/2021] [Indexed: 12/14/2022] Open
Abstract
Interactions between RNA molecules and proteins are critical to many cellular processes and are implicated in various diseases. The RNA-peptide complexes are good model systems to probe the recognition mechanism of RNA by proteins. In this work, we report studies on the binding-unbinding process of a helical peptide from a viral RNA element using nonequilibrium molecular dynamics simulations. We explored the existence of various dissociation pathways with distinct free-energy profiles that reveal metastable states and distinct barriers to peptide dissociation. We also report the free-energy differences for each of the four pathways to be 96.47 ± 12.63, 96.1 ± 10.95, 91.83 ± 9.81, and 92 ± 11.32 kcal/mol. Based on the free-energy analysis, we further propose the preferred pathway and the mechanism of peptide dissociation. The preferred pathway is characterized by the formation of sequential hydrogen-bonding and salt-bridging interactions between several key arginine amino acids and the viral RNA nucleotides. Specifically, we identified one arginine amino acid (R8) of the peptide to play a significant role in the recognition mechanism of the peptide by the viral RNA molecule.
Collapse
Affiliation(s)
- Lev Levintov
- Department of Chemical Engineering, University of New Hampshire, Durham, New Hampshire
| | - Harish Vashisth
- Department of Chemical Engineering, University of New Hampshire, Durham, New Hampshire.
| |
Collapse
|
4
|
Šponer J, Bussi G, Krepl M, Banáš P, Bottaro S, Cunha RA, Gil-Ley A, Pinamonti G, Poblete S, Jurečka P, Walter NG, Otyepka M. RNA Structural Dynamics As Captured by Molecular Simulations: A Comprehensive Overview. Chem Rev 2018; 118:4177-4338. [PMID: 29297679 PMCID: PMC5920944 DOI: 10.1021/acs.chemrev.7b00427] [Citation(s) in RCA: 336] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Indexed: 12/14/2022]
Abstract
With both catalytic and genetic functions, ribonucleic acid (RNA) is perhaps the most pluripotent chemical species in molecular biology, and its functions are intimately linked to its structure and dynamics. Computer simulations, and in particular atomistic molecular dynamics (MD), allow structural dynamics of biomolecular systems to be investigated with unprecedented temporal and spatial resolution. We here provide a comprehensive overview of the fast-developing field of MD simulations of RNA molecules. We begin with an in-depth, evaluatory coverage of the most fundamental methodological challenges that set the basis for the future development of the field, in particular, the current developments and inherent physical limitations of the atomistic force fields and the recent advances in a broad spectrum of enhanced sampling methods. We also survey the closely related field of coarse-grained modeling of RNA systems. After dealing with the methodological aspects, we provide an exhaustive overview of the available RNA simulation literature, ranging from studies of the smallest RNA oligonucleotides to investigations of the entire ribosome. Our review encompasses tetranucleotides, tetraloops, a number of small RNA motifs, A-helix RNA, kissing-loop complexes, the TAR RNA element, the decoding center and other important regions of the ribosome, as well as assorted others systems. Extended sections are devoted to RNA-ion interactions, ribozymes, riboswitches, and protein/RNA complexes. Our overview is written for as broad of an audience as possible, aiming to provide a much-needed interdisciplinary bridge between computation and experiment, together with a perspective on the future of the field.
Collapse
Affiliation(s)
- Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences , Kralovopolska 135 , Brno 612 65 , Czech Republic
| | - Giovanni Bussi
- Scuola Internazionale Superiore di Studi Avanzati , Via Bonomea 265 , Trieste 34136 , Italy
| | - Miroslav Krepl
- Institute of Biophysics of the Czech Academy of Sciences , Kralovopolska 135 , Brno 612 65 , Czech Republic
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science , Palacky University Olomouc , 17. listopadu 12 , Olomouc 771 46 , Czech Republic
| | - Pavel Banáš
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science , Palacky University Olomouc , 17. listopadu 12 , Olomouc 771 46 , Czech Republic
| | - Sandro Bottaro
- Structural Biology and NMR Laboratory, Department of Biology , University of Copenhagen , Copenhagen 2200 , Denmark
| | - Richard A Cunha
- Scuola Internazionale Superiore di Studi Avanzati , Via Bonomea 265 , Trieste 34136 , Italy
| | - Alejandro Gil-Ley
- Scuola Internazionale Superiore di Studi Avanzati , Via Bonomea 265 , Trieste 34136 , Italy
| | - Giovanni Pinamonti
- Scuola Internazionale Superiore di Studi Avanzati , Via Bonomea 265 , Trieste 34136 , Italy
| | - Simón Poblete
- Scuola Internazionale Superiore di Studi Avanzati , Via Bonomea 265 , Trieste 34136 , Italy
| | - Petr Jurečka
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science , Palacky University Olomouc , 17. listopadu 12 , Olomouc 771 46 , Czech Republic
| | - Nils G Walter
- Single Molecule Analysis Group and Center for RNA Biomedicine, Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Michal Otyepka
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science , Palacky University Olomouc , 17. listopadu 12 , Olomouc 771 46 , Czech Republic
| |
Collapse
|
5
|
Krepl M, Cléry A, Blatter M, Allain FHT, Sponer J. Synergy between NMR measurements and MD simulations of protein/RNA complexes: application to the RRMs, the most common RNA recognition motifs. Nucleic Acids Res 2016; 44:6452-70. [PMID: 27193998 PMCID: PMC5291263 DOI: 10.1093/nar/gkw438] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/30/2016] [Accepted: 05/05/2016] [Indexed: 01/28/2023] Open
Abstract
RNA recognition motif (RRM) proteins represent an abundant class of proteins playing key roles in RNA biology. We present a joint atomistic molecular dynamics (MD) and experimental study of two RRM-containing proteins bound with their single-stranded target RNAs, namely the Fox-1 and SRSF1 complexes. The simulations are used in conjunction with NMR spectroscopy to interpret and expand the available structural data. We accumulate more than 50 μs of simulations and show that the MD method is robust enough to reliably describe the structural dynamics of the RRM-RNA complexes. The simulations predict unanticipated specific participation of Arg142 at the protein-RNA interface of the SRFS1 complex, which is subsequently confirmed by NMR and ITC measurements. Several segments of the protein-RNA interface may involve competition between dynamical local substates rather than firmly formed interactions, which is indirectly consistent with the primary NMR data. We demonstrate that the simulations can be used to interpret the NMR atomistic models and can provide qualified predictions. Finally, we propose a protocol for 'MD-adapted structure ensemble' as a way to integrate the simulation predictions and expand upon the deposited NMR structures. Unbiased μs-scale atomistic MD could become a technique routinely complementing the NMR measurements of protein-RNA complexes.
Collapse
Affiliation(s)
- Miroslav Krepl
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, 612 65 Brno, Czech Republic
| | - Antoine Cléry
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Markus Blatter
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland Global Discovery Chemistry, Novartis Institute for BioMedical Research, Basel CH-4002, Switzerland
| | - Frederic H T Allain
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Jiri Sponer
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, 612 65 Brno, Czech Republic CEITEC - Central European Institute of Technology, Masaryk University, Campus Bohunice, Kamenice 5, 625 00 Brno, Czech Republic
| |
Collapse
|
6
|
Duan X, Zhang W, Huang J, Hao L, Wang S, Wang A, Meng D, Zhang Q, Chen Q, Li T. PbWoxT1 mRNA from pear (Pyrus betulaefolia) undergoes long-distance transport assisted by a polypyrimidine tract binding protein. THE NEW PHYTOLOGIST 2016; 210:511-24. [PMID: 26661583 DOI: 10.1111/nph.13793] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 10/25/2015] [Indexed: 05/23/2023]
Abstract
Little is known about the mechanisms by which mRNAs are transported over long distances in the phloem between the rootstock and the scion in grafted woody plants. We identified an mRNA in the pear variety 'Du Li' (Pyrus betulaefolia) that was shown to be transportable in the phloem. It contains a WUSCHEL-RELATED HOMEOBOX (WOX) domain and was therefore named Wox Transport 1 (PbWoxT1). A 548-bp fragment of PbWoxT1 is critical in long-distance transport. PbWoxT1 is rich in CUCU polypyrimidine domains and its mRNAs interact with a polypyrimidine tract binding protein, PbPTB3. Furthermore, the expression of PbWoxT1 significantly increased in the stems of wild-type (WT) tobacco grafted onto the rootstocks of PbWoxT1 or PbPTB3 co-overexpressing lines, but this was not the case in WT plants grafted onto PbWoxT1 overexpressing rootstocks, suggesting that PbPTB3 mediates PbWoxT1 mRNA long-distance transport. We provide novel information that adds a new mechanism with which to explain the noncell-autonomous manner of WOX gene function, which enriches our understanding of how WOX genes work in fruit trees and other species.
Collapse
Affiliation(s)
- Xuwei Duan
- Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing, 100193, China
| | - Wenna Zhang
- Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing, 100193, China
| | - Jing Huang
- Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing, 100193, China
| | - Li Hao
- Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing, 100193, China
| | - Shengnan Wang
- Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing, 100193, China
| | - Aide Wang
- College of Horticulture, Shenyang Agricultural University, Shenyang, 110866, China
| | - Dong Meng
- Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing, 100193, China
| | - Qiulei Zhang
- Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing, 100193, China
| | - Qiuju Chen
- Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing, 100193, China
| | - Tianzhong Li
- Laboratory of Fruit Cell and Molecular Breeding, China Agricultural University, Beijing, 100193, China
| |
Collapse
|
7
|
Cho SK, Sharma P, Butler NM, Kang IH, Shah S, Rao AG, Hannapel DJ. Polypyrimidine tract-binding proteins of potato mediate tuberization through an interaction with StBEL5 RNA. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:6835-47. [PMID: 26283046 PMCID: PMC4623692 DOI: 10.1093/jxb/erv389] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Polypyrimidine tract-binding (PTB) proteins are a family of RNA-binding proteins that function in a wide range of RNA metabolic processes by binding to motifs rich in uracils and cytosines. A PTB protein of pumpkin was identified as the core protein of an RNA-protein complex that trafficks RNA. The biological function of the PTB-RNA complex, however, has not been demonstrated. In potato, six PTB proteins have been identified, and two, designated StPTB1 and StPTB6, are similar to the phloem-mobile pumpkin type. RNA binding assays confirmed the interaction of StPTB1 and StPTB6 with discrete pyrimidine-rich sequences of the 3'-untranslated regions of the phloem-mobile mRNA, StBEL5. The promoter of StPTB1 was active in companion cells of phloem in both stem and petioles. Expression of both types was evident in phloem cells of roots and in stolons during tuber formation. RNA accumulation of both PTB proteins was induced by short days in leaves in correlation with enhanced accumulation of StBEL5 RNA. StPTB suppression lines exhibited reduced tuber yields and decreased StBEL5 RNA accumulation, whereas StPTB overexpression lines displayed an increase in tuber production correlated with the enhanced production in stolons of steady-state levels of StBEL5 transcripts and RNA of key tuber identity genes. In StPTB overexpression lines, both the stability and long-distance transport of StBEL5 transcripts were enhanced, whereas in suppression lines stability and transport decreased. Using a transgenic approach, it is shown that the StPTB family of RNA-binding proteins regulate specific stages of development through an interaction with phloem-mobile transcripts of StBEL5.
Collapse
Affiliation(s)
- Sung Ki Cho
- Plant Biology Major, Iowa State University, Ames, IA 50011-1100, USA
| | - Pooja Sharma
- Plant Biology Major, Iowa State University, Ames, IA 50011-1100, USA
| | | | - Il-Ho Kang
- Plant Biology Major, Iowa State University, Ames, IA 50011-1100, USA
| | - Shweta Shah
- Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - A Gururaj Rao
- Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011, USA
| | - David J Hannapel
- Plant Biology Major, Iowa State University, Ames, IA 50011-1100, USA
| |
Collapse
|
8
|
Lin T, Lashbrook CC, Cho SK, Butler NM, Sharma P, Muppirala U, Severin AJ, Hannapel DJ. Transcriptional analysis of phloem-associated cells of potato. BMC Genomics 2015; 16:665. [PMID: 26335434 PMCID: PMC4558636 DOI: 10.1186/s12864-015-1844-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 08/14/2015] [Indexed: 11/25/2022] Open
Abstract
Background Numerous signal molecules, including proteins and mRNAs, are transported through the architecture of plants via the vascular system. As the connection between leaves and other organs, the petiole and stem are especially important in their transport function, which is carried out by the phloem and xylem, especially by the sieve elements in the phloem system. The phloem is an important conduit for transporting photosynthate and signal molecules like metabolites, proteins, small RNAs, and full-length mRNAs. Phloem sap has been used as an unadulterated source to profile phloem proteins and RNAs, but unfortunately, pure phloem sap cannot be obtained in most plant species. Results Here we make use of laser capture microdissection (LCM) and RNA-seq for an in-depth transcriptional profile of phloem-associated cells of both petioles and stems of potato. To expedite our analysis, we have taken advantage of the potato genome that has recently been fully sequenced and annotated. Out of the 27 k transcripts assembled that we identified, approximately 15 k were present in phloem-associated cells of petiole and stem with greater than ten reads. Among these genes, roughly 10 k are affected by photoperiod. Several RNAs from this day length-regulated group are also abundant in phloem cells of petioles and encode for proteins involved in signaling or transcriptional control. Approximately 22 % of the transcripts in phloem cells contained at least one binding motif for Pumilio, Nova, or polypyrimidine tract-binding proteins in their downstream sequences. Highlighting the predominance of binding processes identified in the gene ontology analysis of active genes from phloem cells, 78 % of the 464 RNA-binding proteins present in the potato genome were detected in our phloem transcriptome. Conclusions As a reasonable alternative when phloem sap collection is not possible, LCM can be used to isolate RNA from specific cell types, and along with RNA-seq, provides practical access to expression profiles of phloem tissue. The combination of these techniques provides a useful approach to the study of phloem and a comprehensive picture of the mechanisms associated with long-distance signaling. The data presented here provide valuable insights into potentially novel phloem-mobile mRNAs and phloem-associated RNA-binding proteins. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1844-2) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Tian Lin
- Plant Biology, Iowa State University, 253 Horticulture Hall, Ames, IA, 50011-1100, USA.
| | - Coralie C Lashbrook
- Plant Biology, Iowa State University, 253 Horticulture Hall, Ames, IA, 50011-1100, USA.
| | - Sung Ki Cho
- Plant Biology, Iowa State University, 253 Horticulture Hall, Ames, IA, 50011-1100, USA.
| | - Nathaniel M Butler
- Plant Biology, Iowa State University, 253 Horticulture Hall, Ames, IA, 50011-1100, USA. .,Department of Plant Breeding, Genetics, and Biotechnology, Michigan State University, East Lansing, MI, 48824, USA.
| | - Pooja Sharma
- Plant Biology, Iowa State University, 253 Horticulture Hall, Ames, IA, 50011-1100, USA.
| | - Usha Muppirala
- Office of Biotechnology, Iowa State University, Ames, IA, 50011-3210, USA.
| | - Andrew J Severin
- Office of Biotechnology, Iowa State University, Ames, IA, 50011-3210, USA.
| | - David J Hannapel
- Plant Biology, Iowa State University, 253 Horticulture Hall, Ames, IA, 50011-1100, USA.
| |
Collapse
|
9
|
Abstract
Recently, recurrent mutations of spliceosomal genes were frequently identified in myeloid malignancies, as well as other types of cancers. One of these spliceosomal genes, U2AF1, was affected by canonical somatic mutations in aggressive type of myeloid malignancies. We hypothesized that U2AF1 mutations causes defects of splicing (missplicing) in specific genes and that such misspliced genes might be important in leukemogenesis. We analyzed RNA deep sequencing to compare splicing patterns of 201 837 exons between the cases with U2AF1 mutations (n = 6) and wild type (n = 14). We identified different alternative splicing patterns in 35 genes comparing cells with mutant and wild-type U2AF1. U2AF1 mutations are associated with abnormal splicing of genes involved in functionally important pathways, such as cell cycle progression and RNA processing. In addition, many of these genes are somatically mutated or deleted in various cancers. Of note is that the alternative splicing patterns associated with U2AF1 mutations were associated with specific sequence signals at the affected splice sites. These novel observations support the hypothesis that U2AF1 mutations play a significant role in myeloid leukemogenesis due to selective missplicing of tumor-associated genes.
Collapse
|
10
|
Reif MM, Winger M, Oostenbrink C. Testing of the GROMOS Force-Field Parameter Set 54A8: Structural Properties of Electrolyte Solutions, Lipid Bilayers, and Proteins. J Chem Theory Comput 2013; 9:1247-1264. [PMID: 23418406 PMCID: PMC3572754 DOI: 10.1021/ct300874c] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Indexed: 11/28/2022]
Abstract
![]()
The GROMOS 54A8 force field [Reif et al. J. Chem.
Theory
Comput.2012, 8, 3705–3723]
is the first of its kind to contain nonbonded parameters for charged
amino acid side chains that are derived in a rigorously thermodynamic
fashion, namely a calibration against single-ion hydration free energies.
Considering charged moieties in solution, the most decisive signature
of the GROMOS 54A8 force field in comparison to its predecessor 54A7
can probably be found in the thermodynamic equilibrium between salt-bridged
ion pair formation and hydration. Possible shifts in this equilibrium
might crucially affect the properties of electrolyte solutions or/and
the stability of (bio)molecules. It is therefore important to investigate
the consequences of the altered description of charged oligoatomic
species in the GROMOS 54A8 force field. The present study focuses
on examining the ability of the GROMOS 54A8 force field to accurately
model the structural properties of electrolyte solutions, lipid bilayers,
and proteins. It is found that (i) aqueous electrolytes
involving oligoatomic species (sodium acetate, methylammonium chloride,
guanidinium chloride) reproduce experimental salt activity derivatives
for concentrations up to 1.0 m (1.0-molal) very well, and good agreement
between simulated and experimental data is also reached for sodium
acetate and methylammonium chloride at 2.0 m concentration, while
not even qualitative agreement is found for sodium chloride throughout
the whole range of examined concentrations, indicating a failure of
the GROMOS 54A7 and 54A8 force-field parameter sets to correctly account
for the balance between ion–ion and ion–water binding
propensities of sodium and chloride ions; (ii) the
GROMOS 54A8 force field reproduces the liquid crystalline-like phase
of a hydrated DPPC bilayer at a pressure of 1 bar and a temperature
of 323 K, the area per lipid being in agreement with experimental
data, whereas other structural properties (volume per lipid, bilayer
thickness) appear underestimated; (iii) the secondary
structure of a range of different proteins simulated with the GROMOS
54A8 force field at pH 7 is maintained and compatible with experimental
NMR data, while, as also observed for the GROMOS 54A7 force field,
α-helices are slightly overstabilized with respect to 310-helices; (iv) with the GROMOS 54A8 force
field, the side chains of arginine, lysine, aspartate, and glutamate
residues appear slightly more hydrated and present a slight excess
of oppositely-charged solution components in their vicinity, whereas
salt-bridge formation properties between charged residues at the protein
surface, as assessed by probability distributions of interionic distances,
are largely equivalent in the GROMOS 54A7 and 54A8 force-field parameter
sets.
Collapse
Affiliation(s)
- Maria M Reif
- Institute for Molecular Modeling and Simulation, University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | | | | |
Collapse
|
11
|
Joseph TT, Osman R. Thermodynamic basis of selectivity in guide-target-mismatched RNA interference. Proteins 2012; 80:1283-98. [PMID: 22275138 DOI: 10.1002/prot.24025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 12/08/2011] [Accepted: 12/21/2011] [Indexed: 01/21/2023]
Abstract
Silencing in RNAi is strongly affected by guide-strand/target-mRNA mismatches. Target nucleation is thought to occur at positions 2-8 of the guide ("seed region"); successful hybridization in this region is the primary determinant of target-binding affinity and hence target cleavage. To define a molecular basis for the target sequence selectivity in RNAi, we studied all possible distinct single mismatches in seven positions of the seed region-a total of 21 substitutions. We report results from soft-core thermodynamic integration simulations to determine changes in targeting binding-free energies to Argonaute due to single mismatches in the guide strand, which arise during binding of an imperfectly matched target mRNA. In agreement with experiment, most mismatches impair target binding, consistent with a prominent role for binding affinity changes in RNAi sequence selectivity. Individual Argonaute residues located near the mismatched base pair are found to contribute significantly to binding affinity changes. We also use this methodology to analyze the mismatch-dependent free energy changes for dissociation of a DNA•RNA hybrid from Argonaute, as a model for the escape of miRNAs from the silencing pathway. Several mismatched sequences of the miRNA have increased affinity to Argonaute, implying that some mismatches may reduce the probability for escape. Furthermore, calculations of base-substitution-dependent free energy changes for binding ssDNA reveal mild sequence sensitivity as expected for guide strand binding to Argonaute. Our findings give a thermodynamic basis for RNAi target sequence selectivity and suggest that miRNA mismatches may increase silencing effectiveness and thus could be evolutionarily advantageous.
Collapse
Affiliation(s)
- Thomas T Joseph
- Department of Structural and Chemical Biology, Mount Sinai School of Medicine, New York University, New York, New York, USA
| | | |
Collapse
|
12
|
Kurisaki I, Fukuzawa K, Nakano T, Mochizuki Y, Watanabe H, Tanaka S. Fragment molecular orbital (FMO) study on stabilization mechanism of neuro-oncological ventral antigen (NOVA)–RNA complex system. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/j.theochem.2010.09.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
13
|
Interactions between PTB RRMs induce slow motions and increase RNA binding affinity. J Mol Biol 2010; 397:260-77. [PMID: 20080103 DOI: 10.1016/j.jmb.2009.12.051] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Revised: 11/19/2009] [Accepted: 12/24/2009] [Indexed: 11/23/2022]
Abstract
Polypyrimidine tract binding protein (PTB) participates in a variety of functions in eukaryotic cells, including alternative splicing, mRNA stabilization, and internal ribosomal entry site-mediated translation initiation. Its mechanism of RNA recognition is determined in part by the novel geometry of its two C-terminal RNA recognition motifs (RRM3 and RRM4), which interact with each other to form a stable complex (PTB1:34). This complex itself is unusual among RRMs, suggesting that it performs a specific function for the protein. In order to understand the advantage it provides to PTB, the fundamental properties of PTB1:34 are examined here as a comparative study of the complex and its two constituent RRMs. Both RRM3 and RRM4 adopt folded structures that NMR data show to be similar to their structure in PRB1:34. The RNA binding properties of the domains differ dramatically. The affinity of each separate RRM for polypyrimidine tracts is far weaker than that of PTB1:34, and simply mixing the two RRMs does not create an equivalent binding platform. (15)N NMR relaxation experiments show that PTB1:34 has slow, microsecond motions throughout both RRMs including the interdomain linker. This is in contrast to the individual domains, RRM3 and RRM4, where only a few backbone amides are flexible on this time scale. The slow backbone dynamics of PTB1:34, induced by packing of RRM3 and RRM4, could be essential for high-affinity binding to a flexible polypyrimidine tract RNA and also provide entropic compensation for its own formation.
Collapse
|
14
|
Schmid N, Bötschi M, Van Gunsteren WF. A GPU solvent-solvent interaction calculation accelerator for biomolecular simulations using the GROMOS software. J Comput Chem 2010; 31:1636-43. [DOI: 10.1002/jcc.21447] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
15
|
Ham BK, Brandom JL, Xoconostle-Cázares B, Ringgold V, Lough TJ, Lucas WJ. A polypyrimidine tract binding protein, pumpkin RBP50, forms the basis of a phloem-mobile ribonucleoprotein complex. THE PLANT CELL 2009; 21:197-215. [PMID: 19122103 PMCID: PMC2648091 DOI: 10.1105/tpc.108.061317] [Citation(s) in RCA: 156] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Revised: 11/13/2008] [Accepted: 12/12/2008] [Indexed: 05/18/2023]
Abstract
RNA binding proteins (RBPs) are integral components of ribonucleoprotein (RNP) complexes and play a central role in RNA processing. In plants, some RBPs function in a non-cell-autonomous manner. The angiosperm phloem translocation stream contains a unique population of RBPs, but little is known regarding the nature of the proteins and mRNA species that constitute phloem-mobile RNP complexes. Here, we identified and characterized a 50-kD pumpkin (Cucurbita maxima cv Big Max) phloem RNA binding protein (RBP50) that is evolutionarily related to animal polypyrimidine tract binding proteins. In situ hybridization studies indicated a high level of RBP50 transcripts in companion cells, while immunolocalization experiments detected RBP50 in both companion cells and sieve elements. A comparison of the levels of RBP50 present in vascular bundles and phloem sap indicated that this protein is highly enriched in the phloem sap. Heterografting experiments confirmed that RBP50 is translocated from source to sink tissues. Collectively, these findings established that RBP50 functions as a non-cell-autonomous RBP. Protein overlay, coimmunoprecipitation, and cross-linking experiments identified the phloem proteins and mRNA species that constitute RBP50-based RNP complexes. Gel mobility-shift assays demonstrated that specificity, with respect to the bound mRNA, is established by the polypyrimidine tract binding motifs within such transcripts. We present a model for RBP50-based RNP complexes within the pumpkin phloem translocation stream.
Collapse
Affiliation(s)
- Byung-Kook Ham
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, California 95616, USA
| | | | | | | | | | | |
Collapse
|