The prosegment catalyzes native folding of Plasmodium falciparum plasmepsin II

Plasmepsin II is a malarial pepsin-like aspartic protease produced as a zymogen containing an N-terminal prosegment domain that is removed during activation. Despite structural similarities between active plasmepsin II and pepsin, their prosegments adopt different conformations in the respective zymogens. In contrast to pepsinogen, the proplasmepsin II prosegment is 80 residues longer, contains a transmembrane region and is non-essential for recombinant expression in an active form, thus calling into question the prosegment's precise function. The present study examines the role of the prosegment in the folding mechanism of plasmepsin II. Both a shorter (residues 77–124) and a longer (residues 65–124) prosegment catalyze plasmepsin II folding at rates more than four orders of magnitude faster compared to folding without prosegment. Native plasmepsin II is kinetically trapped and requires the prosegment both to catalyze folding and to shift the folding equilibrium towards the native conformation. Thus, despite low sequence identity and distinct zymogen conformations, the folding landscapes of plasmepsin II and pepsin, both with and without prosegment, are qualitatively identical. These results imply a conserved and unusual feature of the pepsin-like protease topology that necessitates prosegment-assisted folding

Correction: Resolving nanoscopic structuring and interfacial THz dynamics in setting cements

Correction for ‘Resolving nanoscopic structuring and interfacial THz dynamics in setting cements’ by Fu V. Song et al., Mater. Adv., 2022, 3, 4982–4990, https://doi.org/10.1039/D1MA01002F.Funder: Horizon 2020 Framework Programme; FundRef: https://doi.org/10.13039/10.13039/100010661; Grant(s): ACT, No. 299668 Funder: Engineering and Physical Sciences Research Council; FundRef: https://doi.org/10.13039/10.13039/501100000266; Grant(s): EP/K000128/1, EP/L000202 Funder: Science and Technology Facilities Council; FundRef: https://doi.org/10.13039/10.13039/501100000271; Grant(s): RB1100006, RB1110428 and RB1310334 Funder: Sapienza Università di Roma; FundRef: https://doi.org/10.13039/10.13039/501100004271 Funder: McMaster University; FundRef: https://doi.org/10.13039/10.13039/100009776 Funder: University of British Columbia; FundRef: https://doi.org/10.13039/10.13039/501100005247 Funder: Natural Sciences and Engineering Research Council of Canada; FundRef: https://doi.org/10.13039/10.13039/501100000038; Grant(s): RGPIN 04598, RY

A national network for advanced food and materials

It has been a challenge to link food, health and agriculture in Canada. The Networks of Centers of Excellence (NCEs) was a program established by the Federal Government in 1989 with the goal of mobilizing Canada’s research capability. The government realized that, because the country is so broad geographically, a mechanism was needed to link expertise and build critical mass in certain areas to “mobilize Canada’s research talent in the academic, private and public sectors and apply it to developing the economy and improving the quality of life of Canadians.” Funding comes from the federal granting agencies that are equivalent to the NIH and the NSF in the United States—the Canadian Institutes of Health Research and the Natural Sciences and Engineering Research Council—as well as from the Social Sciences and Humanities Research Council, and Industry Canada, which is a federal government department with the mandate of adding economic benefit to Canada

Protein Structure Insights into the Bilayer Interactions of the Saposin-Like Domain of Solanum tuberosum Aspartic Protease

Abstract Many plant aspartic proteases contain a saposin-like domain whose principal functions are intracellular sorting and host defence. Its structure is characterised by helical segments cross-linked by three highly conserved cystines. The present study on the saposin-like domain of Solanum tuberosum aspartic protease revealed that acidification from inactive to active conditions causes dimerisation and a strand-to-helix secondary structure transition independent of bilayer interaction. Bilayer fusion was shown to occur under reducing conditions yielding a faster shift to larger vesicle sizes relative to native conditions, implying that a lower level structural motif might be bilayer-active. Characterisation of peptide sequences based on the domain’s secondary structural regions showed helix-3 to be active (~4% of the full domain’s activity), and mutation of its sole positively charged residue resulted in loss of activity and disordering of structure. Also, the peptides’ respective circular dichroism spectra suggested that native folding within the full domain is dependent on surrounding structure. Overall, the present study reveals that the aspartic protease saposin-like domain active structure is an open saposin fold dimer whose formation is pH-dependent, and that a bilayer-active motif shared among non-saposin membrane-active proteins including certain plant defence proteins is nested within an overall structure essential for native functionality

Nanotechnology: the word is new but the concept is old. An overview of the science and technology in food and food products at the nanoscale level

Food scientists and technologists are actively engaged in examining and developing nanotechnologies for applications such as novel functional ingredients and nutrient delivery systems, safety testing, packaging, and authenticity/authentication at an ever-increasing pace. However, before these new products/technologies are commercialised, rigorous safety testing and risk/benefit analysis are required to ensure that public and environmental concerns are addressed. This review provides an overview of food nanoscience and technology including a brief history, education, definitions pertaining to policy and regulation, and applications. The most recent findings and advances are emphasised, focussing on bioactives' delivery. In addition, proposed directions in the area of nano-based targeting of pathogens for food safety as well as medical foods are discussed. As food nanoscience and technology has been extensively reviewed in recent years, specific case examples will be limited to those reported within the past year.<br /