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Ng YK, Ikeno S, Kadhim Almansoori AK, Muhammad I, Abdul Rahim R. Characterization of Sphingobacterium sp. Ab3 Lipase and Its Coexpression with LEA Peptides. Microbiol Spectr 2022; 10:e0142221. [PMID: 36314920 PMCID: PMC9769720 DOI: 10.1128/spectrum.01422-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 09/23/2022] [Indexed: 12/24/2022] Open
Abstract
Sphingobacterium sp. is a yellowish Gram-negative bacterium that is usually characterized by high concentrations of sphingophospholipids as lipid components. As microbial enzymes have been in high demand in industrial fields in the past few decades, this study hopes to provide significant information on lipase activities of Sphingobacterium sp., since limited studies have been conducted on the Sphingobacterium sp. lipase. A microbe from one collected Artic soil sample, ARC4, was identified as psychrotolerant Sphingobacterium sp., and it could grow in temperatures ranging from 0°C to 24°C. The expression of Sphingobacterium sp. lipase was successfully performed through an efficient approach of utilizing mutated group 3 late embryogenesis abundant (G3LEA) proteins developed from Polypedilum vanderplanki. Purified enzyme was characterized using a few parameters, such as temperature, pH, metal ion cofactors, organic solvents, and detergents. The expressed enzyme is reported to be cold adapted and has the capability to work efficiently under neutral pH (pH 5.0 to 7.0), cofactors like Na+ ion, and the water-like solvent methanol. Addition of nonionic detergents greatly enhanced the activity of purified enzyme. IMPORTANCE The mechanism of action of LEA proteins has remained unknown to many; in this study we reveal their presence and improved protein expression due to the molecular shielding effect reported by others. This paper should be regarded as a useful example of using such proteins to influence an existing expression system to produce difficult-to-express proteins.
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Affiliation(s)
- You Kiat Ng
- School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia
| | - Shinya Ikeno
- Department of Biological Functions and Engineering, Graduate School of Life Science and System Engineering, Kyushu Institute of Technology, Kitakyushu, Japan
| | | | - Ibrahim Muhammad
- School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia
- Department of Science Lab. Technology, Ramat Polytechnic Maiduguri, Maiduguri, Nigeria
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Tan F, Sun N, Zhang L, Wu J, Xiao S, Tan Q, Uversky VN, Liu Y. Functional characterization of an unknown soybean intrinsically disordered protein in vitro and in Escherichia coli. Int J Biol Macromol 2021; 166:538-549. [PMID: 33137381 DOI: 10.1016/j.ijbiomac.2020.10.211] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 10/25/2020] [Accepted: 10/26/2020] [Indexed: 11/18/2022]
Abstract
Intrinsically disordered proteins (IDPs) possess a wide range of biological function in all organisms, however the specific functions of most IDPs are still unknown. Soybean LOC protein, LOC for short, is a heat-stable protein, which is more abundant in the stress-resistant radicles. Sequence alignment and phylogenetic analysis showed that LOC is a functionally unknown protein and conserved in Fabaceae. LOC, being enriched in most disorder-promoting residues and depleted in most order-promoting residues, was predicted to contain high levels of intrinsic disorder by several commonly used computational tools. However, it was also predicted to contain two disorder-based protein-protein binding sites and two short α-helical segments. The circular dichroism spectroscopic analysis showed that this protein is mostly disordered in water, but can form more α-helical structure in the presence of SDS and TFE. Functional in vitro studies showed that the LOC protein is able to prevent lactate dehydrogenase inactivation by freeze-thaw at a molar ratio of 10:1. Furthermore, in vivo analyses revealed the survival rate of Escherichia coli over-expressing LOC protein under the conditions of osmotic stress was noticeably increased in comparison with the control. These observations suggest that the intrinsically disordered protein LOC might serve as a chaperone and/or cell protector.
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Affiliation(s)
- Fangmei Tan
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong, 518060, PR China
| | - Nan Sun
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong, 518060, PR China
| | - Linsong Zhang
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong, 518060, PR China
| | - Jiahui Wu
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong, 518060, PR China
| | - Shifeng Xiao
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong, 518060, PR China
| | - Qiulong Tan
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong, 518060, PR China
| | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd. MDC07, Tampa, Florida, USA; Laboratory of New Methods in Biology, Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Pushchino, Moscow, region, Russia.
| | - Yun Liu
- Guangdong Provincial Key Laboratory for Plant Epigenetics, Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanography, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong, 518060, PR China.
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Zhang J, Mason AS, Wu J, Liu S, Zhang X, Luo T, Redden R, Batley J, Hu L, Yan G. Identification of Putative Candidate Genes for Water Stress Tolerance in Canola (Brassica napus). FRONTIERS IN PLANT SCIENCE 2015; 6:1058. [PMID: 26640475 PMCID: PMC4661274 DOI: 10.3389/fpls.2015.01058] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 11/13/2015] [Indexed: 05/20/2023]
Abstract
Drought stress can directly inhibit seedling establishment in canola (Brassica napus), resulting in lower plant densities and reduced yields. To dissect this complex trait, 140 B. napus accessions were phenotyped under normal (0.0 MPa, S0) and water-stressed conditions simulated by polyethylene glycol (PEG) 6000 (-0.5 MPa, S5) in a hydroponic system. Phenotypic variation and heritability indicated that the root to shoot length ratio was a reliable indicator for water stress tolerance. Thereafter, 66 accessions (16 water stress tolerant, 34 moderate and 16 sensitive lines) were genotyped using 25,495 Brassica single nucleotide polymorphisms (SNPs). Genome-wide association studies (GWAS) identified 16 loci significantly associated with water stress response. Two B. napus accessions were used for RNA sequencing, with differentially-expressed genes under normal and water-stressed conditions examined. By combining differentially-expressed genes detected by RNA sequencing with significantly associated loci from GWAS, 79 candidate genes were identified, of which eight were putatively associated with drought tolerance based on gene ontology of Arabidopsis. Functional validation of these genes may confirm key drought-related genes for selection and breeding in B. napus. Our results provide insight into the genetic basis of water stress tolerance in canola.
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Affiliation(s)
- Jing Zhang
- Ministry of Agriculture (MOA) Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural UniversityWuhan, China
- Centre for Plant Genetics and Breeding, School of Plant Biology, Faculty of Science and The UWA Institute of Agriculture, The University of Western AustraliaPerth, WA, Australia
| | - Annaliese S. Mason
- Plant Breeding Department, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig UniversityGiessen, Germany
- School of Agriculture and Food Sciences and Centre for Integrative Legume Research, The University of QueenslandBrisbane, QLD, Australia
| | - Jian Wu
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural UniversityWuhan, China
| | - Sheng Liu
- National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural UniversityWuhan, China
| | - Xuechen Zhang
- Centre for Plant Genetics and Breeding, School of Plant Biology, Faculty of Science and The UWA Institute of Agriculture, The University of Western AustraliaPerth, WA, Australia
| | - Tao Luo
- Ministry of Agriculture (MOA) Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural UniversityWuhan, China
| | - Robert Redden
- Australian Grains Genebank, Department of Economic Development Jobs Transport and ResourcesHorsham, VIC, Australia
| | - Jacqueline Batley
- Centre for Plant Genetics and Breeding, School of Plant Biology, Faculty of Science and The UWA Institute of Agriculture, The University of Western AustraliaPerth, WA, Australia
- School of Agriculture and Food Sciences and Centre for Integrative Legume Research, The University of QueenslandBrisbane, QLD, Australia
| | - Liyong Hu
- Ministry of Agriculture (MOA) Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural UniversityWuhan, China
- *Correspondence: Liyong Hu
| | - Guijun Yan
- Centre for Plant Genetics and Breeding, School of Plant Biology, Faculty of Science and The UWA Institute of Agriculture, The University of Western AustraliaPerth, WA, Australia
- Guijun Yan
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Molecular characterization, heterologous expression and resistance analysis of OsLEA3-1 from Oryza sativa. Biologia (Bratisl) 2014. [DOI: 10.2478/s11756-014-0362-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
Intrinsically disordered proteins (IDPs) and IDP regions fail to form a stable structure, yet they exhibit biological activities. Their mobile flexibility and structural instability are encoded by their amino acid sequences. They recognize proteins, nucleic acids, and other types of partners; they accelerate interactions and chemical reactions between bound partners; and they help accommodate posttranslational modifications, alternative splicing, protein fusions, and insertions or deletions. Overall, IDP-associated biological activities complement those of structured proteins. Recently, there has been an explosion of studies on IDP regions and their functions, yet the discovery and investigation of these proteins have a long, mostly ignored history. Along with recent discoveries, we present several early examples and the mechanisms by which IDPs contribute to function, which we hope will encourage comprehensive discussion of IDPs and IDP regions in biochemistry textbooks. Finally, we propose future directions for IDP research.
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Affiliation(s)
- Christopher J Oldfield
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana 46202; ,
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Amara I, Zaidi I, Masmoudi K, Ludevid MD, Pagès M, Goday A, Brini F. Insights into Late Embryogenesis Abundant (LEA) Proteins in Plants: From Structure to the Functions. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/ajps.2014.522360] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Ikeno S, Haruyama T. Boost protein expression through co-expression of LEA-like peptide in Escherichia coli. PLoS One 2013; 8:e82824. [PMID: 24349373 PMCID: PMC3861450 DOI: 10.1371/journal.pone.0082824] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 11/07/2013] [Indexed: 11/26/2022] Open
Abstract
The boost protein expression has been done successfully by simple co-expression with a late embryogenesis abundant (LEA)-like peptide in Escherichia coli. Frequently, overexpression of a recombinant protein fails to provide an adequate yield. In the study, we developed a simple and efficient system for overexpressing transgenic proteins in bacteria by co-expression with an LEA-like peptide. The design of this peptide was based on part of the primary structure of an LEA protein that is known hydrophilic protein to suppress aggregation of other protein molecules. In our system, the expression of the target protein was increased remarkably by co-expression with an LEA-like peptide consisting of only 11 amino acid residues. This could provide a practical method for producing recombinant proteins efficiently.
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Affiliation(s)
- Shinya Ikeno
- Department of Biological Functions and Engineering, Kyushu Institute of Technology, Kitakyushu Science and Research Park, Kitakyushu, Fukuoka, Japan
| | - Tetsuya Haruyama
- Department of Biological Functions and Engineering, Kyushu Institute of Technology, Kitakyushu Science and Research Park, Kitakyushu, Fukuoka, Japan
- * E-mail:
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Wright O, Zhang L, Liu Y, Yoshimi T, Zheng Y, Tunnacliffe A. Critique of the use of fluorescence-based reporters in Escherichia coli
as a screening tool for the identification of peptide inhibitors of Aβ42 aggregation. J Pept Sci 2012; 19:74-83. [DOI: 10.1002/psc.2474] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 10/11/2012] [Accepted: 11/06/2012] [Indexed: 11/09/2022]
Affiliation(s)
- Oliver Wright
- Department of Chemical Engineering and Biotechnology; University of Cambridge; New Museums Site, Pembroke Street Cambridge CB2 3RA UK
| | - Liao Zhang
- Shenzhen Key Laboratory of Microbiology and Gene Engineering; College of Life Sciences; Nanhai Ave 3688 Shenzhen City Guangdong Province China 518060
| | - Yun Liu
- Shenzhen Key Laboratory of Microbiology and Gene Engineering; College of Life Sciences; Nanhai Ave 3688 Shenzhen City Guangdong Province China 518060
| | - Tatsuya Yoshimi
- National Center for Geriatrics and Gerontology; 35 Gengo, Morioka-machi Obu City Aichi 474-8511 Japan
| | - Yizhi Zheng
- Shenzhen Key Laboratory of Microbiology and Gene Engineering; College of Life Sciences; Nanhai Ave 3688 Shenzhen City Guangdong Province China 518060
| | - Alan Tunnacliffe
- Department of Chemical Engineering and Biotechnology; University of Cambridge; New Museums Site, Pembroke Street Cambridge CB2 3RA UK
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Wang WG, Li R, Liu B, Li L, Wang SH, Chen F. Alternatively spliced transcripts of group 3 late embryogenesis abundant protein from Pogonatherum paniceum confer different abiotic stress tolerance in Escherichia coli. JOURNAL OF PLANT PHYSIOLOGY 2012; 169:1559-64. [PMID: 22902206 DOI: 10.1016/j.jplph.2012.06.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 06/14/2012] [Accepted: 06/19/2012] [Indexed: 05/13/2023]
Abstract
The gene encoding a group 3 late embryogenesis abundant (LEA) protein was cloned from callus of the drought-tolerant grass Pogonatherum paniceum. Three alternatively spliced transcripts of this gene were amplified by RT-PCR. According to the bioinformatics analysis, the gene contained three exons and two introns. The PpLEA3.1 transcript which was the most abundant one in P. paniceum contained all three exons, and the PpLEA3.2 transcript lacked fragments of the first two exons which encoded a 41-amino acid-long region of the PpLEA3 protein. The PpLEA3.3 transcript retained the second intron. The three splicing patterns resulted in changes in the number of repeats of an 11-amino acid motif, hydropathy and the predicted 3-dimensional structure. When expressed in Escherichia coli, the three proteins differentially affected growth responses to salt, cold and heat stress. These results confirmed that the complete motif repeat structures and an appropriate hydrophilic/hydrophobic balance are important for the LEA protein in providing protection against various forms of stresses.
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Affiliation(s)
- Wen-Guo Wang
- Biogas Institute of Ministry of Agriculture, Chengdu 610041, PR China
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Santner AA, Croy CH, Vasanwala FH, Uversky VN, Van YYJ, Dunker AK. Sweeping away protein aggregation with entropic bristles: intrinsically disordered protein fusions enhance soluble expression. Biochemistry 2012; 51:7250-62. [PMID: 22924672 DOI: 10.1021/bi300653m] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intrinsically disordered, highly charged protein sequences act as entropic bristles (EBs), which, when translationally fused to partner proteins, serve as effective solubilizers by creating both a large favorable surface area for water interactions and large excluded volumes around the partner. By extending away from the partner and sweeping out large molecules, EBs can allow the target protein to fold free from interference. Using both naturally occurring and artificial polypeptides, we demonstrate the successful implementation of intrinsically disordered fusions as protein solubilizers. The artificial fusions discussed herein have a low level of sequence complexity and a high net charge but are diversified by means of distinctive amino acid compositions and lengths. Using 6xHis fusions as controls, soluble protein expression enhancements from 65% (EB60A) to 100% (EB250) were observed for a 20-protein portfolio. Additionally, these EBs were able to more effectively solubilize targets compared to frequently used fusions such as maltose-binding protein, glutathione S-transferase, thioredoxin, and N utilization substance A. Finally, although these EBs possess very distinct physiochemical properties, they did not perturb the structure, conformational stability, or function of the green fluorescent protein or the glutathione S-transferase protein. This work thus illustrates the successful de novo design of intrinsically disordered fusions and presents a promising technology and complementary resource for researchers attempting to solubilize recalcitrant proteins.
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Affiliation(s)
- Aaron A Santner
- Molecular Kinetics Inc., Indianapolis, Indiana 46268, United States
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Chakrabortee S, Tripathi R, Watson M, Kaminski Schierle GS, Kurniawan DP, Kaminski CF, Wise MJ, Tunnacliffe A. Intrinsically disordered proteins as molecular shields. MOLECULAR BIOSYSTEMS 2012; 8:210-9. [PMID: 21909508 PMCID: PMC5365143 DOI: 10.1039/c1mb05263b] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The broad family of LEA proteins are intrinsically disordered proteins (IDPs) with several potential roles in desiccation tolerance, or anhydrobiosis, one of which is to limit desiccation-induced aggregation of cellular proteins. We show here that this activity, termed molecular shield function, is distinct from that of a classical molecular chaperone, such as HSP70 - while HSP70 reduces aggregation of citrate synthase (CS) on heating, two LEA proteins, a nematode group 3 protein, AavLEA1, and a plant group 1 protein, Em, do not; conversely, the LEA proteins reduce CS aggregation on desiccation, while HSP70 lacks this ability. There are also differences in interaction with client proteins - HSP70 can be co-immunoprecipitated with a polyglutamine-containing client, consistent with tight complex formation, whereas the LEA proteins can not, although a loose interaction is observed by Förster resonance energy transfer. In a further exploration of molecular shield function, we demonstrate that synthetic polysaccharides, like LEA proteins, are able to reduce desiccation-induced aggregation of a water-soluble proteome, consistent with a steric interference model of anti-aggregation activity. If molecular shields operate by reducing intermolecular cohesion rates, they should not protect against intramolecular protein damage. This was tested using the monomeric red fluorescent protein, mCherry, which does not undergo aggregation on drying, but the absorbance and emission spectra of its intrinsic fluorophore are dramatically reduced, indicative of intramolecular conformational changes. As expected, these changes are not prevented by AavLEA1, except for a slight protection at high molar ratios, and an AavLEA1-mCherry fusion protein is damaged to the same extent as mCherry alone. A recent hypothesis proposed that proteomes from desiccation-tolerant species contain a higher degree of disorder than intolerant examples, and that this might provide greater intrinsic stability, but a bioinformatics survey does not support this, since there are no significant differences in the degree of disorder between desiccation tolerant and intolerant species. It seems clear therefore that molecular shield function is largely an intermolecular activity implemented by specialist IDPs, distinct from molecular chaperones, but with a role in proteostasis.
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Affiliation(s)
- Sohini Chakrabortee
- Cell and Organism Engineering Laboratory, Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK
| | - Rashmi Tripathi
- Cell and Organism Engineering Laboratory, Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK
| | - Matthew Watson
- Cell and Organism Engineering Laboratory, Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK
| | - Gabriele S. Kaminski Schierle
- Laser Analytics Group, Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK
| | - Davy P. Kurniawan
- Cell and Organism Engineering Laboratory, Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK
| | - Clemens F. Kaminski
- Laser Analytics Group, Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK
- School of Advanced Optical Technologies, Max Planck Institute for the Science of Light, Günther Scharowski Strasse 1, Erlangen, Germany
| | - Michael J. Wise
- Biomolecular, Biomedical and Chemical Sciences, University of Western Australia, Crawley WA 6009, Australia
| | - Alan Tunnacliffe
- Cell and Organism Engineering Laboratory, Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK
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Top A, Roberts CJ, Kiick KL. Conformational and aggregation properties of a PEGylated alanine-rich polypeptide. Biomacromolecules 2011; 12:2184-92. [PMID: 21553871 DOI: 10.1021/bm200272w] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The conformational and aggregation behavior of PEG conjugates of an alanine-rich polypeptide (PEG-c17H6) were investigated and compared to that of the polypeptide equipped with a deca-histidine tag (17H6). These polypeptides serve as simple and stimuli-responsive models for the aggregation behavior of helix-rich proteins, as our previous studies have shown that the helical 17H6 self-associates at acidic pH and converts to β-sheet structures at elevated temperature under acidic conditions. In the work here, we show that PEG-c17H6 also adopts a helical structure at ambient/subambient temperatures, at both neutral and acidic pH. The thermal denaturation behavior of 17H6 and PEG-c17H6 is similar at neutral pH, where the alanine-rich domain has no self-association tendency. At acidic pH and elevated temperature, however, PEGylation slows β-sheet formation of c17H6, and reduces the apparent cooperativity of thermally induced unfolding. Transmission electron microscopy of PEG-c17H6 conjugates incubated at elevated temperatures showed fibrils with widths of ∼20-30 nm, wider than those observed for fibrils of 17H6. These results suggest that PEGylation reduces β-sheet aggregation in these polypeptides by interfering, only after unfolding of the native helical structure, with interprotein conformational changes needed to form β-sheet aggregates.
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Affiliation(s)
- Ayben Top
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA
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Burra PV, Kalmar L, Tompa P. Reduction in structural disorder and functional complexity in the thermal adaptation of prokaryotes. PLoS One 2010; 5:e12069. [PMID: 20711457 PMCID: PMC2920320 DOI: 10.1371/journal.pone.0012069] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Accepted: 07/07/2010] [Indexed: 01/20/2023] Open
Abstract
Genomic correlates of evolutionary adaptation to very low or very high optimal growth temperature (OGT) values have been the subject of many studies. Whereas these provided a protein-structural rationale of the activity and stability of globular proteins/enzymes, the point has been neglected that adaptation to extreme temperatures could also have resulted from an increased use of intrinsically disordered proteins (IDPs), which are resistant to these conditions in vitro. Contrary to these expectations, we found a conspicuously low level of structural disorder in bacteria of very high (and very low) OGT values. This paucity of disorder does not reflect phylogenetic relatedness, i.e. it is a result of genuine adaptation to extreme conditions. Because intrinsic disorder correlates with important regulatory functions, we asked how these bacteria could exist without IDPs by studying transcription factors, known to harbor a lot of function-related intrinsic disorder. Hyperthermophiles have much less transcription factors, which have reduced disorder compared to their mesophilic counterparts. On the other hand, we found by systematic categorization of proteins with long disordered regions that there are certain functions, such as translation and ribosome biogenesis that depend on structural disorder even in hyperthermophiles. In all, our observations suggest that adaptation to extreme conditions is achieved by a significant functional simplification, apparent at both the level of the genome and individual genes/proteins.
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Affiliation(s)
- Prasad V. Burra
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States of America
| | - Lajos Kalmar
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, Budapest, Hungary
| | - Peter Tompa
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, Budapest, Hungary
- * E-mail:
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