Cassandra Terry - Academia.edu (original) (raw)

Papers by Cassandra Terry

The Role of Fenugreek in the Management of Type 2 Diabetes

International journal of molecular sciences, Jun 26, 2024

Bioscience Reports, May 1, 2022

There are over 40 identified human disorders that involve certain proteins folding incorrectly, a... more There are over 40 identified human disorders that involve certain proteins folding incorrectly, accumulating in the body causing damage to cells and organs and causing disease. Type 2 Diabetes Mellitus (T2DM) is one of these protein misfolding disorders (PMDs) and involves human islet amyloid polypeptide (hIAPP) misfolding and accumulating in parts of the body, primarily in the pancreas, causing damage to islet cells and affecting glucose regulation. In this review, we have summarised our current understanding of what causes hIAPP to misfold, what conformations are found in different parts of the body with a particular focus on what is known about the structure of hIAPP and how this links to T2DM. Understanding the molecular basis behind these misfolding events is essential for understanding the role of hIAPP to develop better therapeutics since type 2 diabetes currently affects over 4.9 million people in the United Kingdom alone and is predicted to increase as our population ages.

Life, Apr 14, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

PLOS ONE, Aug 24, 2011

In members of the Bacillus cereus group the outermost layer of the spore is the exosporium, which... more In members of the Bacillus cereus group the outermost layer of the spore is the exosporium, which interacts with hosts and the environment. Efforts have been made to identify proteins of the exosporium but only a few have so far been characterised and their role in determining spore architecture and spore function is still poorly understood. We have characterised the exosporium protein, YwdL. DywdL spores have a more fragile exosporium, subject to damage on repeated freeze-thawing, although there is no evidence of altered resistance properties, and coats appear intact. Immunogold labelling and Western blotting with anti-YwdL antibodies identified YwdL to be located exclusively on the inner surface of the exosporium of B. cereus and B. thuringiensis. We conclude that YwdL is important for formation of a robust exosporium but is not required to maintain the crystalline assembly within the basal layer or for attachment of the hairy nap structure. DywdL spores are unable to germinate in response to CaDPA, and have altered germination properties, a phenotype that confirms the expected defect in localization of the cortex lytic enzyme CwlJ in the coat.

Acta Crystallographica Section D-biological Crystallography, Jul 21, 2004

A genetically modi®ed (His 6-tagged) form of the mitochondrial F 1-ATPase (MW = 370 kDa) has been... more A genetically modi®ed (His 6-tagged) form of the mitochondrial F 1-ATPase (MW = 370 kDa) has been puri®ed from the yeast Saccharomyces cerevisiae and crystallized in the presence of polythelene glycol (PEG) 6000 as a precipitant, 1 mM NiCl 2 , 1 mM Mg AMP-PNP and 50 mM Mg ADP. X-ray diffraction data were obtained on three separate occasions using synchrotron radiation, with a progression in the quality of the diffraction data, which improved from 3.3 to 3.0 to 2.8 A Ê. On the second occasion, the diffraction was improved by a crystal-annealing procedure. The crystals belong to the monoclinic space group P2 1 , with unit-cell parameters a = 110.6, b = 294.2, c = 190.4 A Ê , = 101.6. The asymmetric unit contains three molecules of yeast F 1 , with a corresponding volume per protein weight (V M) of 2.8 A Ê 3 Da À1 and a solvent content of 55%.

Molecular Microbiology, Mar 8, 2017

Bioscience Reports

Multimodal Technologies and Interaction

Here we describe a proof-of-concept case study focusing on the design and development of a novel ... more Here we describe a proof-of-concept case study focusing on the design and development of a novel computer interface that uses facial muscles to control interactivity within a virtual environment. We have developed a system comprised of skin-mounted electrodes that detect underlying muscle activity through electromyography. The signals from the electrodes are filtered and smoothed, then used as input data to an application that displays a virtual environment with a 3D animated avatar. The user’s expressions control the facial movements of the avatar, thus conveying user emotions through real-time animation of a representative face in a virtual scenario. To achieve this, we collaborated with our Public and Patient Involvement focus group to discuss concepts and design appropriate interactions, while simultaneously developing a prototype system. Programmers and 3D artists worked together to create a system whereby individual user facial muscles are connected to 3D animated models of th...

Life

Cases of Type 2 Diabetes Mellitus (T2DM) are increasing at an alarming rate due to the rise in ob... more Cases of Type 2 Diabetes Mellitus (T2DM) are increasing at an alarming rate due to the rise in obesity, sedentary lifestyles, glucose-rich diets and other factors. Numerous studies have increasingly illustrated the pivotal role that human islet amyloid polypeptide (hIAPP) plays in the pathology of T2DM through damage and subsequent loss of pancreatic β-cell mass. HIAPP can misfold and form amyloid fibrils which are preceded by pre-fibrillar oligomers and monomers, all of which have been linked, to a certain extent, to β-cell cytotoxicity through a range of proposed mechanisms. This review provides an up-to-date summary of recent progress in the field, highlighting factors that contribute to hIAPP misfolding and aggregation such as hIAPP protein concentration, cell stress, molecular chaperones, the immune system response and cross-seeding with other amyloidogenic proteins. Understanding the structure of hIAPP and how these factors affect amyloid formation will help us better understa...

Current Research in Biotechnology, 2020

The clinical beliefs (expectations and demands) of veterinarians regarding herd-level strategies ... more The clinical beliefs (expectations and demands) of veterinarians regarding herd-level strategies to control mastitis, lameness, and Johne's disease were quantified in a numerical format; 94 veterinarians working in England (UK) were randomly selected and, during interviews, a statistical technique called probabilistic elicitation was used to capture their clinical expectations as probability distributions. The results revealed that markedly different clinical expectations existed for all 3 diseases, and many pairs of veterinarians had expectations with nonoverlapping 95% Bayesian credible intervals. For example, for a 3-yr lameness intervention, the most pessimistic veterinarian was centered at an 11% population mean reduction in lameness prevalence (95% credible interval: 0-21%); the most enthusiastic veterinarian was centered at a 58% reduction (95% credible interval: 38-78%). This suggests that a major change in beliefs would be required to achieve clinical agreement. Veterinarians' clinical expectations were used as priors in Bayesian models where they were combined with synthetic data (from randomized clinical trials of different sizes) to explore the effect of new evidence on current clinical opinion. The mathematical models make predictions based on the assumption that veterinarians will update their beliefs logically. For example, for the lameness intervention, a 200-farm clinical trial that estimated a 30% mean reduction in lameness prevalence was predicted to be reasonably convincing to the most pessimist veterinarian; that is, in light of this data, they were predicted to believe there would be a 0.92 probability of exceeding the median clinical demand of this sample of veterinarians, which was a 20% mean reduction in lameness. Currently, controversy exists over the extent to which veterinarians update their beliefs logically, and further research on this is needed. This study has demonstrated that probabilistic elicitation and a Bayesian framework are useful for evaluating the diversity and strength of veterinarians' clinical beliefs. The wide variations observed have implications for designing future projects. Although many factors influence disease control, nonetheless the heterogeneity in beliefs also raises concern over the extent to which a broadly consistent approach is currently being achieved; it supports the argument for more randomized clinical trials and for national programs to control nonstatutory endemic diseases.

Acta Cryst. (2004). D60, 14411444 DOI: 10.1107/S0907444904012661 1441 Acta Crystallographica Section D

Ni-chelate-affinity purification and crystallization of the yeast mitochondrial F1-ATPase

Protein expression and purification, 2004

The yeast mitochondrial ATPase has been genetically modified to include a His(6) Ni-affinity tag ... more The yeast mitochondrial ATPase has been genetically modified to include a His(6) Ni-affinity tag on the amino end of the mature beta-subunit. The modified beta-subunit is imported into the mitochondrion, properly processed to the mature form, and assembled into a mature and fully active ATP synthase. The F(1)-ATPase has been purified from submitochondrial particles after release from the membrane with chloroform, followed by Ni-chelate-affinity and gel filtration chromatography. The final enzyme is a homogeneous preparation with full activity and no apparent degradation products. This enzyme preparation has been used to obtain crystals that diffract to better than 2.8 A resolution.

YwdL in Bacillus cereus: Its Role in Germination and Exosporium Structure

PLoS ONE, 2011

Molecular microbiology, May 18, 2017

Bacteria of the genera Bacillus and Clostridium form highly resistant spores, which in the case o... more Bacteria of the genera Bacillus and Clostridium form highly resistant spores, which in the case of some pathogens act as the infectious agents. An exosporium forms the outermost layer of some spores; it plays roles in protection, adhesion, dissemination, host targeting in pathogens, and germination control. The exosporium of the Bacillus cereus group, including the anthrax pathogen, contains a 2D-crystalline basal layer, overlaid by a hairy nap. BclA and related proteins form the hairy nap, and require ExsFA (BxpB) for their localisation on the basal layer. Until now, the identity of the main structural protein components of the basal layer were unknown. We demonstrate here that ExsY forms one of the essential components. Through heterologous expression in E. coli, we also demonstrate that ExsY can self-assemble into ordered 2D arrays that mimic the structure of the exosporium basal layer. Self-assembly is likely to play an important role in the construction of the exosporium. The E...

Frontiers in Molecular Neuroscience, Jul 9, 2019

Prions are lethal pathogens, which cause fatal neurodegenerative diseases in mammals. They are un... more Prions are lethal pathogens, which cause fatal neurodegenerative diseases in mammals. They are unique infectious agents and are composed of self-propagating multi-chain assemblies of misfolded host-encoded prion protein (PrP). Understanding prion structure is fundamental to understanding prion disease pathogenesis however to date, the high-resolution structure of authentic ex vivo infectious prions remains unknown. Advances in determining prion structure have been severely impeded by the difficulty in recovering relatively homogeneous prion particles from infected brain and definitively associating infectivity with the PrP assembly state. Recently, however, images of highly infectious ex vivo PrP rods that produce prion-strain specific disease phenotypes in mice have been obtained using cryo-electron microscopy and atomic force microscopy. These images have provided the most detailed description of ex vivo mammalian prions reported to date and have established that prions isolated from multiple strains have a common hierarchical structure. Misfolded PrP is assembled into 20 nm wide rods containing two fibers, each with double helical repeating substructure, separated by a characteristic central gap 8-10 nm in width. Irregularly structured material with adhesive properties distinct to that of the fibers is present within the central gap of the rod. Prions are clearly distinguishable from non-infectious recombinant PrP fibrils generated in vitro and from all other propagating protein structures so far described in other neurodegenerative diseases. The basic architecture of mammalian prions appears to be exceptional and fundamental to their lethal pathogenicity.

Open Biology, May 1, 2016

Mammalian prions are hypothesized to be fibrillar or amyloid forms of prion protein (PrP), but st... more Mammalian prions are hypothesized to be fibrillar or amyloid forms of prion protein (PrP), but structures observed to date have not been definitively correlated with infectivity and the three-dimensional structure of infectious prions has remained obscure. Recently, we developed novel methods to obtain exceptionally pure preparations of prions from mouse brain and showed that pathogenic PrP in these high-titre preparations is assembled into rod-like assemblies. Here, we have used precise cell culture-based prion infectivity assays to define the physical relationship between the PrP rods and prion infectivity and have used electron tomography to define their architecture. We show that infectious PrP rods isolated from multiple prion strains have a common hierarchical assembly comprising twisted pairs of short fibres with repeating substructure. The architecture of the PrP rods provides a new structural basis for understanding prion infectivity and can explain the inability to systematically generate high-titre synthetic prions from recombinant PrP.

Until now, the 3-dimensional structure of infectious mammalian prions and how this differs from n... more Until now, the 3-dimensional structure of infectious mammalian prions and how this differs from non-infectious amyloid fibrils remained unknown. Mammalian prions are hypothesized to be fibrillar or amyloid forms of prion protein (PrP), but structures observed to date have not been definitively correlated with infectivity. One of the major challenges has been the production of highly homogeneous material of demonstrable high specific infectivity to allow direct correlation of particle structure with infectivity. We have recently developed novel methods to obtain exceptionally pure preparations of prions from prion-infected murine brain and have shown that pathogenic PrP in these hightiter preparations is assembled into rod-like assemblies (Wenborn et al. 2015. Sci. Rep. 10062). Our preparations contain very high titres of infectious prions which faithfully transmit prion strain-specific phenotypes when inoculated into mice making them eminently suitable for detailed structural analysis. We are now undertaking structural characterization of prion assemblies and comparing these to the structure of non-infectious PrP fibrils generated from recombinant PrP.

Infected PK1/2 cells generate PrPSc by recruitment of PrPC which occurs at a rate faster than the... more Infected PK1/2 cells generate PrPSc by recruitment of PrPC which occurs at a rate faster than the cells innate clearance systems and dilutional effect of cell division, thus the cells remain chronically infected. However when ADDLs are added they bind to PrPC at the cell surface preventing conversion to PrPSc. This reduction in the conversion rate allows the PrPSc to be cleared over time, resulting in reduction in PrPSc levels and cell curing.

Supplementary material from "Soluble Aβ aggregates can inhibit prion propagation

Mammalian prions cause lethal neurodegenerative diseases such as Creutzfeldt–Jakob disease (CJD) ... more Mammalian prions cause lethal neurodegenerative diseases such as Creutzfeldt–Jakob disease (CJD) and consist of multi-chain assemblies of misfolded cellular prion protein (PrPC). Ligands that bind to PrPC can inhibit prion propagation and neurotoxicity. Extensive prior work established that certain soluble assemblies of the Alzheimer's disease (AD)-associated amyloid β-protein (Aβ) can tightly bind to PrPC, and that this interaction may be relevant to their toxicity in AD. Here, we investigated whether such soluble Aβ assemblies might, conversely, have an inhibitory effect on prion propagation. Using cellular models of prion infection and propagation and distinct Aβ preparations, we found that the form of Aβ assemblies which most avidly bound to PrP in vitro also inhibited prion infection and propagation. By contrast, forms of Aβ which exhibit little or no binding to PrP were unable to attenu...