scholarly journals In Vivo Bypass of Chaperone by Extended Coiled-Coil Motif in T4 Tail Fiber

2004 ◽  
Vol 186 (24) ◽  
pp. 8363-8369 ◽  
Author(s):  
Yun Qu ◽  
Paul Hyman ◽  
Timothy Harrah ◽  
Edward Goldberg
Keyword(s):  
Bacteriophage T4 ◽  
Coiled Coil ◽  
Critical Factor ◽  
Coiled Coils ◽  
Temperature Sensitive ◽  
Tail Fiber ◽  
Type Gene ◽  
In Vivo Screen

ABSTRACT The distal-half tail fiber of bacteriophage T4 is made of three gene products: trimeric gp36 and gp37 and monomeric gp35. Chaperone P38 is normally required for folding gp37 peptides into a P37 trimer; however, a temperature-sensitive mutation in T4 (ts3813) that suppresses this requirement at 30°C but not at 42°C was found in gene 37 (R. J. Bishop and W. B. Wood, Virology 72:244-254, 1976). Sequencing of the temperature-sensitive mutant revealed a 21-bp duplication of wild-type gene 37 inserted into its C-terminal portion (S. Hashemolhosseini et al., J. Mol. Biol. 241:524-533, 1994). We noticed that the 21-amino-acid segment encompassing this duplication in the ts3813 mutant has a sequence typical of a coiled coil and hypothesized that its extension would relieve the temperature sensitivity of the ts3813 mutation. To test our hypothesis, we crossed the T4 ts3813 mutant with a plasmid encoding an engineered pentaheptad coiled coil. Each of the six mutants that we examined retained two amber mutations in gene 38 and had a different coiled-coil sequence varying from three to five heptads. While the sequences varied, all maintained the heptad-repeating coiled-coil motif and produced plaques at up to 50°C. This finding strongly suggests that the coiled-coil motif is a critical factor in the folding of gp37. The presence of a terminal coiled-coil-like sequence in the tail fiber genes of 17 additional T-even phages implies the conservation of this mechanism. The increased melting temperature should be useful for “clamps” to initiate the folding of trimeric β-helices in vitro and as an in vivo screen to identify, sequence, and characterize trimeric coiled coils.

scholarly journals The Skn7 Response Regulator ofSaccharomyces cerevisiaeInteracts with Hsf1 In Vivo and Is Required for the Induction of Heat Shock Genes by Oxidative Stress

2000 ◽  
Vol 11 (7) ◽  
pp. 2335-2347 ◽  
Author(s):  
Desmond C. Raitt ◽  
Anthony L. Johnson ◽  
Alexander M. Erkine ◽  
Kozo Makino ◽  
Brian Morgan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Heat Shock ◽  
Response Regulator ◽  
Coiled Coil ◽  
Normal Growth ◽  
Temperature Sensitive ◽  
Regulatory Sequences ◽  
Heat Shock Genes

The Skn7 response regulator has previously been shown to play a role in the induction of stress-responsive genes in yeast, e.g., in the induction of the thioredoxin gene in response to hydrogen peroxide. The yeast Heat Shock Factor, Hsf1, is central to the induction of another set of stress-inducible genes, namely the heat shock genes. These two regulatory trans-activators, Hsf1 and Skn7, share certain structural homologies, particularly in their DNA-binding domains and the presence of adjacent regions of coiled-coil structure, which are known to mediate protein–protein interactions. Here, we provide evidence that Hsf1 and Skn7 interact in vitro and in vivo and we show that Skn7 can bind to the same regulatory sequences as Hsf1, namely heat shock elements. Furthermore, we demonstrate that a strain deleted for the SKN7 gene and containing a temperature-sensitive mutation in Hsf1 is hypersensitive to oxidative stress. Our data suggest that Skn7 and Hsf1 cooperate to achieve maximal induction of heat shock genes in response specifically to oxidative stress. We further show that, like Hsf1, Skn7 can interact with itself and is localized to the nucleus under normal growth conditions as well as during oxidative stress.

scholarly journals Coiled-Coil Trigger Motifs in the 1B and 2B Rod Domain Segments Are Required for the Stability of Keratin Intermediate Filaments

2000 ◽  
Vol 11 (10) ◽  
pp. 3539-3558 ◽  
Author(s):  
Kenneth C. Wu ◽  
Janine T. Bryan ◽  
Maria I. Morasso ◽  
Shyh-Ing Jang ◽  
Jeung-Hoon Lee ◽  
...  
Keyword(s):  
Coiled Coil ◽  
Coiled Coils ◽  
Detectable Effect ◽  
Keratin 5 ◽  
Molecular Stability ◽  
Potential Trigger ◽  
Helical Proteins ◽  
The Stability

Many α-helical proteins that form two-chain coiled coils possess a 13-residue trigger motif that seems to be required for the stability of the coiled coil. However, as currently defined, the motif is absent from intermediate filament (IF) protein chains, which nevertheless form segmented two-chain coiled coils. In the present work, we have searched for and identified two regions in IF chains that are essential for the stability necessary for the formation of coiled-coil molecules and thus may function as trigger motifs. We made a series of point substitutions with the keratin 5/keratin 14 IF system. Combinations of the wild-type and mutant chains were assembled in vitro and in vivo, and the stabilities of two-chain (one-molecule) and two-molecule assemblies were examined with use of a urea disassembly assay. Our new data document that there is a region located between residues 100 and 113 of the 2B rod domain segment that is absolutely required for molecular stability and IF assembly. This potential trigger motif differs slightly from the consensus in having an Asp residue at position 4 (instead of a Glu) and a Thr residue at position 9 (instead of a charged residue), but there is an absolute requirement for a Glu residue at position 6. Because these 13 residues are highly conserved, it seems possible that this motif functions in all IF chains. Likewise, by testing keratin IF with substitutions in both chains, we identified a second potential trigger motif between residues 79 and 91 of the 1B rod domain segment, which may also be conserved in all IF chains. However, we were unable to find a trigger motif in the 1A rod domain segment. In addition, many other point substitutions had little detectable effect on IF assembly, except for the conserved Lys-23 residue of the 2B rod domain segment. Cross-linking and modeling studies revealed that Lys-23 may lie very close to Glu-106 when two molecules are aligned in the A22 mode. Thus, the Glu-106 residue may have a dual role in IF structure: it may participate in trigger formation to afford special stability to the two-chain coiled-coil molecule, and it may participate in stabilization of the two-molecule hierarchical stage of IF structure.

scholarly journals Structural and Functional Analysis of Essential pre-mRNA Splicing Factor Prp19p

2005 ◽  
Vol 25 (1) ◽  
pp. 451-460 ◽  
Author(s):  
Melanie D. Ohi ◽  
Craig W. Vander Kooi ◽  
Joshua A. Rosenberg ◽  
Liping Ren ◽  
Justin P. Hirsch ◽  
...  
Keyword(s):  
Functional Data ◽  
Coiled Coil ◽  
Single Copy ◽  
Coiled Coils ◽  
Binding Partner ◽  
Central Stalk ◽  
Interaction Surface

ABSTRACT U-box-containing Prp19p is an integral component of the Prp19p-associated complex (the nineteen complex, or NTC) that is essential for activation of the spliceosome. Prp19p makes numerous protein-protein contacts with other NTC components and is required for NTC stability. Here we show that Prp19p forms a tetramer in vitro and in vivo and we map the domain required for its oligomerization to a central tetrameric coiled-coil. Biochemical and in vivo analyses are consistent with Prp19p tetramerization providing an interaction surface for a single copy of its binding partner, Cef1p. Electron microscopy showed that the isolated Prp19p tetramer is an elongated particle consisting of four globular WD40 domains held together by a central stalk consisting of four N-terminal U-boxes and four coiled-coils. These structural and functional data provide a basis for understanding the role of Prp19p as a key architectural component of the NTC.

scholarly journals The preprophase band-associated kinesin-14 OsKCH2 is a processive minus-end-directed microtubule motor

2017 ◽  
Author(s):  
Kuo-Fu Tseng ◽  
Pan Wang ◽  
Yuh-Ru Julie Lee ◽  
Joel Bowen ◽  
Allison M. Gicking ◽  
...  
Keyword(s):  
Coiled Coil ◽  
Preprophase Band ◽  
Cytoplasmic Dynein ◽  
Coiled Coils ◽  
Land Plants ◽  
Actin Binding ◽  
Actin Binding Domain ◽  
Microtubule Motor

AbstractIn animals and fungi, cytoplasmic dynein is a processive motor that plays dominant roles in various intracellular processes. In contrast, land plants lack cytoplasmic dynein but contain many minus-end-directed kinesin-14s. No plant kinesin-14 is known to produce processive motility as a homodimer. OsKCH2 is a plant-specific kinesin-14 with an N-terminal actin-binding domain and a central motor domain flanked by two predicted coiled-coils (CC1 and CC2). Here, we show that OsKCH2 specifically decorates preprophase band microtubules in vivo and transports actin filaments along microtubules in vitro. Importantly, OsKCH2 exhibits processive minus-end-directed motility on single microtubules as individual homodimers. We find that CC1 but not CC2 forms the coiled-coil for OsKCH2 dimerization. Instead, CC2 functions to enable OsKCH2 processivity by enhancing its binding to microtubules. Collectively, these results show that land plants have evolved unconventional kinesin-14 homodimers with inherent minus-end-directed processivity that may function to compensate for the loss of cytoplasmic dynein.

scholarly journals Phosphorylation of the Mitotic Regulator Protein Hec1 by Nek2 Kinase Is Essential for Faithful Chromosome Segregation

2002 ◽  
Vol 277 (51) ◽  
pp. 49408-49416 ◽  
Author(s):  
Yumay Chen ◽  
Daniel J. Riley ◽  
Lei Zheng ◽  
Phang-Lang Chen ◽  
Wen-Hwa Lee
Keyword(s):  
Chromosome Segregation ◽  
Critical Role ◽  
Coiled Coil ◽  
Serine Phosphorylation ◽  
Yeast Cells ◽  
Temperature Sensitive ◽  
Chromosomal Segregation ◽  
M Phase

Hec1 (highlyexpressed incancer) plays essential roles in chromosome segregation by interacting through its coiled-coil domains with several proteins that modulate the G2/M phase. Hec1 localizes to kinetochores, and its inactivation either by genetic deletion or antibody neutralization leads to severe and lethal chromosomal segregation errors, indicating that Hec1 plays a critical role in chromosome segregation. The mechanisms by which Hec1 is regulated, however, are not known. Here we show that human Hec1 is a serine phosphoprotein and that it binds specifically to the mitotic regulatory kinase Nek2 during G2/M. Nek2 phosphorylates Hec1 on serine residue 165, bothin vitroandin vivo. Yeast cells are viable without scNek2/Kin3, a close structural homolog of Nek2 that binds to both human and yeast Hec1. When the same yeasts carry an scNek2/Kin3 (D55G) or Nek2 (E38G) mutation to mimic a similar temperature-sensitivenimamutation inAspergillus, their growth is arrested at the nonpermissive temperature, because the scNek2/Kin3 (D55G) mutant binds to Hec1 but fails to phosphorylate it. Whereas wild-type human Hec1 rescues lethality resulting from deletion of Hec1 inSaccharomyces cerevesiae, a human Hec1 mutant or yeast Hec1 mutant changing Ser165to Ala or yeast Hec1 mutant changing Ser201to Ala does not. Mutations changing the same Ser residues to Glu, to mimic the negative charge created by phosphorylation, partially rescue lethality but result in a high incidence of errors in chromosomal segregation. These results suggest that cell cycle-regulated serine phosphorylation of Hec1 by Nek2 is essential for faithful chromosome segregation.

scholarly journals Structure and function of Spc42 coiled-coils in yeast centrosome assembly and duplication

2019 ◽  
Vol 30 (12) ◽  
pp. 1505-1522 ◽  
Author(s):  
Amanda C. Drennan ◽  
Shivaani Krishna ◽  
Mark A. Seeger ◽  
Michael P. Andreas ◽  
Jennifer M. Gardner ◽  
...  
Keyword(s):  
Coiled Coil ◽  
Core Layer ◽  
Spindle Pole ◽  
Coiled Coils ◽  
Lipid Monolayer ◽  
Functional Roles ◽  
Spindle Pole Bodies ◽  
And Function

Centrosomes and spindle pole bodies (SPBs) are membraneless organelles whose duplication and assembly is necessary for bipolar mitotic spindle formation. The structural organization and functional roles of major proteins in these organelles can provide critical insights into cell division control. Spc42, a phosphoregulated protein with an N-terminal dimeric coiled-coil (DCC), assembles into a hexameric array at the budding yeast SPB core, where it functions as a scaffold for SPB assembly. Here, we present in vitro and in vivo data to elucidate the structural arrangement and biological roles of Spc42 elements. Crystal structures reveal details of two additional coiled-coils in Spc42: a central trimeric coiled-coil and a C-terminal antiparallel DCC. Contributions of the three Spc42 coiled-coils and adjacent undetermined regions to the formation of an ∼145 Å hexameric lattice in an in vitro lipid monolayer assay and to SPB duplication and assembly in vivo reveal structural and functional redundancy in Spc42 assembly. We propose an updated model that incorporates the inherent symmetry of these Spc42 elements into a lattice, and thereby establishes the observed sixfold symmetry. The implications of this model for the organization of the central SPB core layer are discussed.

scholarly journals Evaluation of the Safety and Immune Efficacy of Recombinant Human Respiratory Syncytial Virus Strain Long Live Attenuated Vaccine Candidates

2021 ◽  
Author(s):  
Li-Nan Wang ◽  
Xiang-Lei Peng ◽  
Min Xu ◽  
Yuan-Bo Zheng ◽  
Yue-Ying Jiao ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Gene Deletion ◽  
Human Respiratory Syncytial Virus ◽  
Temperature Sensitive ◽  
T7 Promoter ◽  
Vaccine Candidates ◽  
Rsv Infection ◽  
Syncytial Virus

AbstractHuman respiratory syncytial virus (RSV) infection is the leading cause of lower respiratory tract illness (LRTI), and no vaccine against LRTI has proven to be safe and effective in infants. Our study assessed attenuated recombinant RSVs as vaccine candidates to prevent RSV infection in mice. The constructed recombinant plasmids harbored (5′ to 3′) a T7 promoter, hammerhead ribozyme, RSV Long strain antigenomic cDNA with cold-passaged (cp) mutations or cp combined with temperature-sensitive attenuated mutations from the A2 strain (A2cpts) or further combined with SH gene deletion (A2cptsΔSH), HDV ribozyme (δ), and a T7 terminator. These vectors were subsequently co-transfected with four helper plasmids encoding N, P, L, and M2-1 viral proteins into BHK/T7-9 cells, and the recovered viruses were then passaged in Vero cells. The rescued recombinant RSVs (rRSVs) were named rRSV-Long/A2cp, rRSV-Long/A2cpts, and rRSV-Long/A2cptsΔSH, respectively, and stably passaged in vitro, without reversion to wild type (wt) at sites containing introduced mutations or deletion. Although rRSV-Long/A2cpts and rRSV-Long/A2cptsΔSH displayed  temperature-sensitive (ts) phenotype in vitro and in vivo, all rRSVs were significantly attenuated in vivo. Furthermore, BALB/c mice immunized with rRSVs produced Th1-biased immune response, resisted wtRSV infection, and were free from enhanced respiratory disease. We showed that the combination of ΔSH with attenuation (att) mutations of cpts contributed to improving att phenotype, efficacy, and gene stability of rRSV. By successfully introducing att mutations and SH gene deletion into the RSV Long parent and producing three rRSV strains, we have laid an important foundation for the development of RSV live attenuated vaccines.

scholarly journals Important Role for Phylogenetically Invariant PP2Acα Active Site and C-Terminal Residues Revealed by Mutational Analysis in Saccharomyces cerevisiae

Genetics ◽  
2000 ◽  
Vol 156 (1) ◽  
pp. 21-29 ◽  
Author(s):  
David R H Evans ◽  
Brian A Hemmings
Keyword(s):  
Protein Interactions ◽  
Active Site ◽  
Protein Function ◽  
Mutational Analysis ◽  
Yeast Cells ◽  
Temperature Sensitive ◽  
Active Site Residues ◽  
Catalytic Function

Abstract PP2A is a central regulator of eukaryotic signal transduction. The human catalytic subunit PP2Acα functionally replaces the endogenous yeast enzyme, Pph22p, indicating a conservation of function in vivo. Therefore, yeast cells were employed to explore the role of invariant PP2Ac residues. The PP2Acα Y127N substitution abolished essential PP2Ac function in vivo and impaired catalysis severely in vitro, consistent with the prediction from structural studies that Tyr-127 mediates substrate binding and its side chain interacts with the key active site residues His-118 and Asp-88. The V159E substitution similarly impaired PP2Acα catalysis profoundly and may cause global disruption of the active site. Two conditional mutations in the yeast Pph22p protein, F232S and P240H, were found to cause temperature-sensitive impairment of PP2Ac catalytic function in vitro. Thus, the mitotic and cell lysis defects conferred by these mutations result from a loss of PP2Ac enzyme activity. Substitution of the PP2Acα C-terminal Tyr-307 residue by phenylalanine impaired protein function, whereas the Y307D and T304D substitutions abolished essential function in vivo. Nevertheless, Y307D did not reduce PP2Acα catalytic activity significantly in vitro, consistent with an important role for the C terminus in mediating essential protein-protein interactions. Our results identify key residues important for PP2Ac function and characterize new reagents for the study of PP2A in vivo.

scholarly journals C-Terminal Deletions Can Suppress Temperature-Sensitive Mutations and Change Dominance in the Phage Mu Repressor

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 661-672 ◽  
Author(s):  
Jodi L Vogel ◽  
Vincent Geuskens ◽  
Lucie Desmet ◽  
N Patrick Higgins ◽  
Ariane Toussaint
Keyword(s):  
Binding Activity ◽  
Temperature Sensitive ◽  
Dna Binding Activity ◽  
Heat Stable ◽  
C Terminus ◽  
Acid Domain ◽  
Mutant Forms ◽  
Amino Acid Domain

Abstract Mutations in an N-terminal 70-amino acid domain of bacteriophage Mu's repressor cause temperature-sensitive DNA-binding activity. Surprisingly, amber mutations can conditionally correct the heat-sensitive defect in three mutant forms of the repressor gene, cts25 (D43-G), cts62 (R47-Q and cts71 (M28-I), and in the appropriate bacterial host produce a heat-stable Sts phenotype (for survival of temperature shifts). Sts repressor mutants are heat sensitive when in supE or supF hosts and heat resistant when in Sup° hosts. Mutants with an Sts phenotype have amber mutations at one of three codons, Q179, Q187, or Q190. The Sts phenotype relates to the repressor size: in Sup° hosts sts repressors are shorter by seven, 10, or 18 amino acids compared to repressors in supE or supF hosts. The truncated form of the sts62-1 repressor, which lacks 18 residues (Q179–V196), binds Mu operator DNA more stably at 42° in vitro compared to its full-length counterpart (cts62 repressor). In addition to influencing temperature sensitivity, the C-terminus appears to control the susceptibility to in vivo Clp proteolysis by influencing the multimeric structure of repressor.

scholarly journals Mapping of a Yeast G Protein βγ Signaling Interaction

Genetics ◽  
1998 ◽  
Vol 150 (4) ◽  
pp. 1407-1417 ◽  
Author(s):  
Simon J Dowell ◽  
Anne L Bishop ◽  
Susan L Dyos ◽  
Andrew J Brown ◽  
Malcolm S Whiteway
Keyword(s):  
Signal Transduction ◽  
Map Kinase ◽  
G Protein ◽  
Coiled Coil ◽  
Receptor Activation ◽  
Temperature Sensitive ◽  
Hydrophobic Residues ◽  
Map Kinase Cascade ◽  
Kinase Cascade

Abstract The mating pathway of Saccharomyces cerevisiae is widely used as a model system for G protein-coupled receptor-mediated signal transduction. Following receptor activation by the binding of mating pheromones, G protein βγ subunits transmit the signal to a MAP kinase cascade, which involves interaction of Gβ (Ste4p) with the MAP kinase scaffold protein Ste5p. Here, we identify residues in Ste4p required for the interaction with Ste5p. These residues define a new signaling interface close to the Ste20p binding site within the Gβγ coiled-coil. Ste4p mutants defective in the Ste5p interaction interact efficiently with Gpa1p (Gα) and Ste18p (Gγ) but cannot function in signal transduction because cells expressing these mutants are sterile. Ste4 L65S is temperature-sensitive for its interaction with Ste5p, and also for signaling. We have identified a Ste5p mutant (L196A) that displays a synthetic interaction defect with Ste4 L65S, providing strong evidence that Ste4p and Ste5p interact directly in vivo through an interface that involves hydrophobic residues. The correlation between disruption of the Ste4p-Ste5p interaction and sterility confirms the importance of this interaction in signal transduction. Identification of the Gβγ coiled-coil in Ste5p binding may set a precedent for Gβγ-effector interactions in more complex organisms.

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