Synthetic model proteins: the relative contribution of leucine residues at the nonequivalent positions of the 3-4 hydrophobic repeat to the stability of the two-stranded .alpha.-helical coiled-coil

Biochemistry ◽  
1992 ◽  
Vol 31 (25) ◽  
pp. 5739-5746 ◽  
Author(s):  
Nian E. Zhou ◽  
Cyril M. Kay ◽  
Robert S. Hodges
Keyword(s):  
Coiled Coil ◽  
Synthetic Model ◽  
Relative Contribution ◽  
The Stability

scholarly journals An Assessment of the Usefulness of Money for Policy in the Philippines

2006 ◽  
Vol 5 (1) ◽  
pp. 142-176 ◽  
Author(s):  
Maria Socorro Gochoco-Bautista
Keyword(s):  
The Philippines ◽  
Forecast Errors ◽  
Empirical Relationships ◽  
Clear Cut ◽  
Relative Contribution ◽  
Limited Support ◽  
Causality Tests ◽  
Ultimate Objective ◽  
The Stability ◽  
Definition Of

This study assesses the usefulness of money for policy in the Philippines. The basic idea behind the use of monetary aggregates for policy is that observed fluctuations in money anticipate movements in the ultimate objective of monetary policy, such as inflation control. The paper examines the stability of key empirical relationships, including the behavior of velocity and the presence of cointegrating relationships among money and variables of interest to policymakers. In general, results indicate that the stability of velocity and the presence of cointegrating relationships lend some limited support to the potential usefulness of money for policy. The ability of money to predict inflation is examined using Granger causality tests and an unrestricted vector autoregression (VAR) that examines the relative contribution of innovations in money to the variance of the forecast errors in inflation. In general, money's ability to predict inflation is less clear-cut and seems to be dependent on the ordering and lag lengths of the variables used in the VAR and the definition of money used.

scholarly journals Relative roles of endolithic algae and carbonate chemistry variability in the skeletal dissolution of crustose coralline algae

2014 ◽  
Vol 11 (17) ◽  
pp. 4615-4626 ◽  
Author(s):  
C. Reyes-Nivia ◽  
G. Diaz-Pulido ◽  
S. Dove
Keyword(s):  
Coralline Algae ◽  
Crustose Coralline Algae ◽  
Carbonate Chemistry ◽  
Erosion Rates ◽  
Relative Contribution ◽  
Endolithic Algae ◽  
Seawater Carbonate Chemistry ◽  
The Stability ◽  
Business As Usual ◽  
Constant Dark

Abstract. The susceptibility of crustose coralline algae (CCA) skeletons to dissolution is predicted to increase as oceans warm and acidify. Skeletal dissolution is caused by bioerosion from endolithic microorganisms and by chemical processes associated with undersaturation of carbonate minerals in seawater. Yet, the relative contribution of algal microborers and seawater carbonate chemistry to the dissolution of organisms that cement reefs under projected pCO2 and temperature (pCO2-T) scenarios have not been quantified. We exposed CCA skeletons (Porolithon onkodes) to four pCO2-T treatments (pre-industrial, present-day, SRES-B1 "reduced" pCO2, and SRES-A1FI "business-as-usual" pCO2 emission scenarios) under natural light cycles vs. constant dark conditions for 8 weeks. Dissolution rates of skeletons without photo-endoliths were dramatically higher (200%) than those colonized by endolithic algae across all pCO2-T scenarios. This suggests that daytime photosynthesis by microborers counteract dissolution by reduced saturation states resulting in lower net erosion rates over day–night cycles. Regardless of the presence or absence of phototrophic microborers, skeletal dissolution increased significantly under the spring A1FI "business-as-usual" scenario, confirming the CCA sensitivity to future oceans. Projected ocean acidity and temperature may significantly disturb the stability of reef frameworks cemented by CCA, but surficial substrates harbouring photosynthetic microborers will be less impacted than those without algal endoliths.

scholarly journals Phosphoregulation of tropomyosin is crucial for actin cable turnover and division site placement

2019 ◽  
Vol 218 (11) ◽  
pp. 3548-3559 ◽  
Author(s):  
Saravanan Palani ◽  
Darius V. Köster ◽  
Tomoyuki Hatano ◽  
Anton Kamnev ◽  
Taishi Kanamaru ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Actin Filaments ◽  
Coiled Coil ◽  
Actin Binding ◽  
Division Site ◽  
Actin Cable ◽  
Nonmuscle Cells ◽  
The Stability ◽  
Actin Cables

Tropomyosin is a coiled-coil actin binding protein key to the stability of actin filaments. In muscle cells, tropomyosin is subject to calcium regulation, but its regulation in nonmuscle cells is not understood. Here, we provide evidence that the fission yeast tropomyosin, Cdc8, is regulated by phosphorylation of a serine residue. Failure of phosphorylation leads to an increased number and stability of actin cables and causes misplacement of the division site in certain genetic backgrounds. Phosphorylation of Cdc8 weakens its interaction with actin filaments. Furthermore, we show through in vitro reconstitution that phosphorylation-mediated release of Cdc8 from actin filaments facilitates access of the actin-severing protein Adf1 and subsequent filament disassembly. These studies establish that phosphorylation may be a key mode of regulation of nonmuscle tropomyosins, which in fission yeast controls actin filament stability and division site placement.

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 Nanoscale spatial dependence of avidity in an IgG1 antibody

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Agnieszka Jendroszek ◽  
Magnus Kjaergaard
Keyword(s):  
Spatial Dependence ◽  
Target Recognition ◽  
Coiled Coil ◽  
Coiled Coils ◽  
Antibody Engineering ◽  
Bispecific Antibodies ◽  
Secreted Proteins ◽  
Biophysical Techniques ◽  
The Stability ◽  
20 Nm

AbstractAntibodies are secreted proteins that are crucial to recognition of pathogens by the immune system and are also efficient pharmaceuticals. The affinity and specificity of target recognition can increase remarkably through avidity effects, when the antibody can bind a multivalent antigen through more than one epitope simultaneously. A key goal of antibody engineering is thus to optimize avidity, but little is known about the nanoscale spatial dependence of avidity in antibodies. Here, we develop a set of anti-parallel coiled-coils spanning from 7 to 20 nm and validate their structure using biophysical techniques. We use the coiled-coils to control the spacing between two epitopes, and measure how antigen spacing affects the stability of the bivalent antibody:antigen complex. We find a maximal avidity enhancement at a spacing of 13 nm. In contrast to recent studies, we find the avidity to be relatively insensitive to epitope spacing near the avidity maximum as long as it is within the spatial tolerance of the antibody. We thus only see a ~ twofold variation of avidity in the range from 7 to 20 nm. The coiled-coil systems developed here may prove a useful protein nanocaliper for profiling the spatial tolerance and avidity profile of bispecific antibodies.

scholarly journals Metabolic enzyme clustering by coiled coils improves the biosynthesis of resveratrol and mevalonate

2020 ◽  
Author(s):  
Tina Fink ◽  
Bojana Stevović ◽  
René Verwaal ◽  
Johannes A. Roubos ◽  
Rok Gaber ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Noncovalent Interactions ◽  
Coiled Coil ◽  
Product Yield ◽  
Coiled Coils ◽  
Metabolic Enzyme ◽  
Biosynthetic Enzymes ◽  
Reaction Products ◽  
Interaction Domains ◽  
The Stability

Abstract The clustering of biosynthetic enzymes is used in nature to channel reaction products and increase the yield of compounds produced by multiple reaction steps. The coupling of multiple enzymes has been shown to increase the biosynthetic product yield. Different clustering strategies have particular advantages as the spatial organization of multiple enzymes creates biocatalytic cascades with a higher efficiency of biochemical reaction. However, there are also some drawbacks, such as misfolding and the variable stability of interaction domains, which may differ between particular biosynthetic reactions and the host organism. Here, we compared different protein-based clustering strategies, including direct fusion, fusion mediated by intein, and noncovalent interactions mediated through small coiled-coil dimer-forming domains. The clustering of enzymes through orthogonally designed coiled-coil interaction domains increased the production of resveratrol in Escherichia coli more than the intein-mediated fusion of biosynthetic enzymes. The improvement of resveratrol production correlated with the stability of the coiled-coil dimers. The coiled-coil fusion-based approach also increased mevalonate production in Saccharomyces cerevisiae , thus demonstrating the wider applicability of this strategy.

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