{"title":"The power and challenge of lipid (a)symmetry across the membrane and cell.","authors":"Mikhail Bogdanov","doi":"10.1042/ETLS20220088","DOIUrl":"10.1042/ETLS20220088","url":null,"abstract":"<p><p>Membrane asymmetry means that the two sides of membrane are structurally, physically and functionally different. Membrane asymmetry is largely related to the lipid sidedness and particularly to compositional (lipid head and acyl group) and physical (lipid packing order, charge, hydration and H-bonding interactions) differences in the inner and outer leaflets of lipid bilayer. Chemically, structurally and conformationally different non-covalent bound lipid molecules are physically fluid and deformable and enable to interact dynamically to form transient arrangements with asymmetry both perpendicular and parallel to the plane of the lipid bilayer. Although biological membranes are almost universally asymmetric however the asymmetry is not absolute since only drastic difference in the number of lipids per leaflet is found and symmetric arrangements are possible. Asymmetry is thought to direct and influence many core biological functions by altering the membrane's collective biochemical, biophysical and structural properties. Asymmetric transbilayer lipid distribution is found across all lipid classes, cells and near all endomembrane compartments. Why cell membranes are (a)symmetric and adopt almost exclusively highly entropically disfavored asymmetric state?</p>","PeriodicalId":46394,"journal":{"name":"Emerging Topics in Life Sciences","volume":"7 1","pages":"1-6"},"PeriodicalIF":3.3,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10725184/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9247482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Renovating a double fence with or without notifying the next door and across the street neighbors: why the biogenic cytoplasmic membrane of Gram-negative bacteria display asymmetry?","authors":"Mikhail Bogdanov","doi":"10.1042/ETLS20230042","DOIUrl":"10.1042/ETLS20230042","url":null,"abstract":"<p><p>The complex two-membrane organization of the envelope of Gram-negative bacteria imposes an unique biosynthetic and topological constraints that can affect translocation of lipids and proteins synthesized on the cytoplasm facing leaflet of the cytoplasmic (inner) membrane (IM), across the IM and between the IM and outer membrane (OM). Balanced growth of two membranes and continuous loss of phospholipids in the periplasmic leaflet of the IM as metabolic precursors for envelope components and for translocation to the OM requires a constant supply of phospholipids in the IM cytosolic leaflet. At present we have no explanation as to why the biogenic E. coli IM displays asymmetry. Lipid asymmetry is largely related to highly entropically disfavored, unequal headgroup and acyl group asymmetries which are usually actively maintained by active mechanisms. However, these mechanisms are largely unknown for bacteria. Alternatively, lipid asymmetry in biogenic IM could be metabolically controlled in order to maintain uniform bilayer growth and asymmetric transmembrane arrangement by balancing temporally the net rates of synthesis and flip-flop, inter IM and OM bidirectional flows and bilayer chemical and physical properties as spontaneous response. Does such flippase-less or 'lipid only\", 'passive' mechanism of generation and maintenance of lipid asymmetry exists in the IM? The driving force for IM asymmetry can arise from the packing requirements imposed upon the bilayer system during cell division through disproportional distribution of two negatively curved phospholipids, phosphatidylethanolamine and cardiolipin, with consistent reciprocal tendency to increase and decrease lipid order in each membrane leaflet respectively.</p>","PeriodicalId":46394,"journal":{"name":"Emerging Topics in Life Sciences","volume":"7 1","pages":"137-150"},"PeriodicalIF":3.8,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10725183/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9252658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Artificial cell design: reconstructing biology for life science applications.","authors":"Basusree Ghosh","doi":"10.1042/ETLS20220050","DOIUrl":"10.1042/ETLS20220050","url":null,"abstract":"<p><p>Artificial cells are developed to redesign novel biological functions in a programmable and tunable manner. Although it aims to reconstitute living cell features and address 'origin of life' related questions, rapid development over the years has transformed artificial cells into an engineering tool with huge potential in applied biotechnology. Although the application of artificial cells was introduced decades ago as drug carriers, applications in other sectors are relatively new and could become possible with the technological advancement that can modulate its designing principles. Artificial cells are non-living system that includes no prerequisite designing modules for their formation and therefore allow freedom of assembling desired biological machinery within a physical boundary devoid of complex contemporary living-cell counterparts. As stimuli-responsive biomimetic tools, artificial cells are programmed to sense the surrounding, recognise their target, activate its function and perform the defined task. With the advantage of their customised design, artificial cells are being studied in biosensing, drug delivery, anti-cancer therapeutics or artificial photosynthesis type fields. This mini-review highlights those advanced fields where artificial cells with a minimalistic setup are developed as user-defined custom-made microreactors, targeting to reshape our future 'life'.</p>","PeriodicalId":46394,"journal":{"name":"Emerging Topics in Life Sciences","volume":"6 6","pages":"619-627"},"PeriodicalIF":3.4,"publicationDate":"2022-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10446828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tony Z Jia, Tommaso Bellini, Noel Clark, Tommaso P Fraccia
{"title":"A liquid crystal world for the origins of life.","authors":"Tony Z Jia, Tommaso Bellini, Noel Clark, Tommaso P Fraccia","doi":"10.1042/ETLS20220081","DOIUrl":"https://doi.org/10.1042/ETLS20220081","url":null,"abstract":"Nucleic acids (NAs) in modern biology accomplish a variety of tasks, and the emergence of primitive nucleic acids is broadly recognized as a crucial step for the emergence of life. While modern NAs have been optimized by evolution to accomplish various biological functions, such as catalysis or transmission of genetic information, primitive NAs could have emerged and been selected based on more rudimental chemical-physical properties, such as their propensity to self-assemble into supramolecular structures. One such supramolecular structure available to primitive NAs are liquid crystal (LC) phases, which are the outcome of the collective behavior of short DNA or RNA oligomers or monomers that self-assemble into linear aggregates by combinations of pairing and stacking. Formation of NA LCs could have provided many essential advantages for a primitive evolving system, including the selection of potential genetic polymers based on structure, protection by compartmentalization, elongation, and recombination by enhanced abiotic ligation. Here, we review recent studies on NA LC assembly, structure, and functions with potential prebiotic relevance. Finally, we discuss environmental or geological conditions on early Earth that could have promoted (or inhibited) primitive NA LC formation and highlight future investigation axes essential to further understanding of how LCs could have contributed to the emergence of life.","PeriodicalId":46394,"journal":{"name":"Emerging Topics in Life Sciences","volume":"6 6","pages":"557-569"},"PeriodicalIF":3.8,"publicationDate":"2022-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10452738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A mini-review on bio-inspired polymer self-assembly: single-component and interactive polymer systems.","authors":"Xiangxi Meng","doi":"10.1042/ETLS20220057","DOIUrl":"https://doi.org/10.1042/ETLS20220057","url":null,"abstract":"<p><p>Biology demonstrates meticulous ways to control biomaterials self-assemble into ordered and disordered structures to carry out necessary bioprocesses. Empowering the synthetic polymers to self-assemble like biomaterials is a hallmark of polymer physics studies. Unlike protein engineering, polymer science demystifies self-assembly by purposely embedding particular functional groups into the backbone of the polymer while isolating others. The polymer field has now entered an era of advancing materials design by mimicking nature to a very large extend. For example, we can make sequence-specific polymers to study highly ordered mesostructures similar to studying proteins, and use charged polymers to study liquid-liquid phase separation as in membraneless organelles. This mini-review summarizes recent advances in studying self-assembly using bio-inspired strategies on single-component and multi-component systems. Sequence-defined techniques are used to make on-demand hybrid materials to isolate the effects of chirality and chemistry in synthetic block copolymer self-assembly. In the meantime, sequence patterning leads to more hierarchical assemblies comprised of only hydrophobic and hydrophilic comonomers. The second half of the review discusses complex coacervates formed as a result of the associative charge interactions of oppositely charged polyelectrolytes. The tunable phase behavior and viscoelasticity are unique in studying liquid macrophase separation because the slow polymer relaxation comes primarily from charge interactions. Studies of bio-inspired polymer self-assembly significantly impact how we optimize user-defined materials on a molecular level.</p>","PeriodicalId":46394,"journal":{"name":"Emerging Topics in Life Sciences","volume":"6 6","pages":"593-607"},"PeriodicalIF":3.8,"publicationDate":"2022-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10813680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Self-assembly and biophysical properties of archaeal lipids.","authors":"Ahanjit Bhattacharya","doi":"10.1042/ETLS20220062","DOIUrl":"https://doi.org/10.1042/ETLS20220062","url":null,"abstract":"<p><p>Archaea constitute one of the three fundamental domains of life. Archaea possess unique lipids in their cell membranes which distinguish them from bacteria and eukaryotes. This difference in lipid composition is referred to as 'Lipid Divide' and its origins remain elusive. Chemical inertness and the highly branched nature of the archaeal lipids afford the membranes stability against extremes of temperature, pH, and salinity. Based on the molecular architecture, archaeal polar lipids are of two types - monopolar and bipolar. Both monopolar and bipolar lipids have been shown to form vesicles and other well-defined membrane architectures. Bipolar archaeal lipids are among the most unique lipids found in nature because of their membrane-spanning nature and mechanical stability. The majority of the self-assembly studies on archaeal lipids have been carried out using crude polar lipid extracts or molecular mimics. The complexity of the archaeal lipids makes them challenging to synthesize chemically, and as a result, studies on pure lipids are few. There is an ongoing effort to develop simplified routes to synthesize complex archaeal lipids to facilitate diverse biophysical studies and pharmaceutical applications. Investigation on archaeal lipids may help us understand how life survives in extreme conditions and therefore unlock some of the mysteries surrounding the origins of cellular life.</p>","PeriodicalId":46394,"journal":{"name":"Emerging Topics in Life Sciences","volume":"6 6","pages":"571-582"},"PeriodicalIF":3.8,"publicationDate":"2022-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10814191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Assembly methods for asymmetric lipid and polymer-lipid vesicles.","authors":"Yuting Huang","doi":"10.1042/ETLS20220055","DOIUrl":"https://doi.org/10.1042/ETLS20220055","url":null,"abstract":"<p><p>Asymmetric unilamellar vesicles are aqueous bodies surrounded by two dissimilar leaflets made from lipids, polymers, or both. They are great models for cell membranes and attractive vehicles in potential biomedicine applications. Despite their promise, asymmetric unilamellar vesicles are not widely studied or adopted in applications. This is largely due to the complexity in generating asymmetric membranes. Recent technical advances in microfluidics have opened doors to high throughput fabrication of asymmetric unilamellar vesicles. In this review, we focus on microfluidic methods for generating asymmetric lipid vesicles, with two dissimilar lipid leaflets, and asymmetric lipid-polymer vesicles, with one lipid leaflet and one polymer leaflet. We also review a few standard non-microfluidic methods for generating asymmetric vesicles. We hope to highlight the improved capability in obtaining asymmetric vesicles through a variety of methods and encourage the wider scientific community to adopt some of these for their own work.</p>","PeriodicalId":46394,"journal":{"name":"Emerging Topics in Life Sciences","volume":"6 6","pages":"609-617"},"PeriodicalIF":3.8,"publicationDate":"2022-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10814833","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Scratching beyond the surface - minimal actin assemblies as tools to elucidate mechanical reinforcement and shape change.","authors":"Anders Aufderhorst-Roberts, Margarita Staykova","doi":"10.1042/ETLS20220052","DOIUrl":"10.1042/ETLS20220052","url":null,"abstract":"<p><p>The interaction between the actin cytoskeleton and the plasma membrane in eukaryotic cells is integral to a large number of functions such as shape change, mechanical reinforcement and contraction. These phenomena are driven by the architectural regulation of a thin actin network, directly beneath the membrane through interactions with a variety of binding proteins, membrane anchoring proteins and molecular motors. An increasingly common approach to understanding the mechanisms that drive these processes is to build model systems from reconstituted lipids, actin filaments and associated actin-binding proteins. Here we review recent progress in this field, with a particular emphasis on how the actin cytoskeleton provides mechanical reinforcement, drives shape change and induces contraction. Finally, we discuss potential future developments in the field, which would allow the extension of these techniques to more complex cellular processes.</p>","PeriodicalId":46394,"journal":{"name":"Emerging Topics in Life Sciences","volume":" ","pages":""},"PeriodicalIF":3.8,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9788373/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10549431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Exploring the realm of soft matter biophysics: an early career perspective.","authors":"Natasha H Rhys","doi":"10.1042/ETLS20220110","DOIUrl":"10.1042/ETLS20220110","url":null,"abstract":"<p><p>This special issue of Emerging Topics in Life Sciences presents a selection of reviews that give insight into the vast array of research taking place in the fields of soft matter and biophysics, and where these two intersect. The reviews here cover the full range from the fundamentals of how biological systems may have assembled to how we can use this insight to develop and exploit new biomaterials for the future, all informed through the lens of the physical sciences. This issue has been both written and edited by early career researchers, highlighting the cutting-edge contributions that this generation of researchers is bringing to the field.</p>","PeriodicalId":46394,"journal":{"name":"Emerging Topics in Life Sciences","volume":" ","pages":""},"PeriodicalIF":3.8,"publicationDate":"2022-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10401101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The elegant complexity of fear in non-human animals.","authors":"Marie-H Monfils, Michael Domjan","doi":"10.1042/ETLS20220001","DOIUrl":"https://doi.org/10.1042/ETLS20220001","url":null,"abstract":"<p><p>Activation of the fear system is adaptive, and protects individuals from impending harm; yet, exacerbation of the fear system is at the source of anxiety-related disorders. Here, we briefly review the 'why' and 'how' of fear, with an emphasis on models that encapsulate the elegant complexity of rodents' behavioral responding in the face of impending harm, and its relevance to developing treatment interventions.</p>","PeriodicalId":46394,"journal":{"name":"Emerging Topics in Life Sciences","volume":"6 5","pages":"445-455"},"PeriodicalIF":3.8,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/0e/c6/ETLS-6-445.PMC9788375.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10492591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}