Structural Basis for Dual-Inhibition Mechanism of a Non-Classical Kazal-Type Serine Protease Inhibitor from Horseshoe Crab in Complex with Subtilisin

Serine proteases play a crucial role in host-pathogen interactions. In the innate immune system of invertebrates, multi-domain protease inhibitors are important for the regulation of host-pathogen interactions and antimicrobial activities. Serine protease inhibitors, 9.3-kDa CrSPI isoforms 1 and 2, have been identified from the hepatopancreas of the horseshoe crab, Carcinoscorpius rotundicauda. The CrSPIs were biochemically active, especially CrSPI-1, which potently inhibited subtilisin (Ki = 1.43 nM). CrSPI has been grouped with the non-classical Kazal-type inhibitors due to its unusual cysteine distribution. Here we report the crystal structure of CrSPI-1 in complex with subtilisin at 2.6 Å resolution and the results of biophysical interaction studies. The CrSPI-1 molecule has two domains arranged in an extended conformation. These two domains act as heads that independently interact with two separate subtilisin molecules, resulting in the inhibition of subtilisin activity at a ratio of 1:2 (inhibitor to protease). Each subtilisin molecule interacts with the reactive site loop from each domain of CrSPI-1 through a standard canonical binding mode and forms a single ternary complex. In addition, we propose the substrate preferences of each domain of CrSPI-1. Domain 2 is specific towards the bacterial protease subtilisin, while domain 1 is likely to interact with the host protease, Furin. Elucidation of the structure of the CrSPI-1: subtilisin (1∶2) ternary complex increases our understanding of host-pathogen interactions in the innate immune system at the molecular level and provides new strategies for immunomodulation

The origin and composition of carbonatite-derived carbonate-bearing fluorapatite deposits

Carbonate-bearing fluorapatite rocks occur at over 30 globally distributed carbonatite complexes and represent a substantial potential supply of phosphorus for the fertiliser industry. However, the process(es) involved in forming carbonate-bearing fluorapatite at some carbonatites remain equivocal, with both hydrothermal and weathering mechanisms inferred. In this contribution, we compare the paragenesis and trace element contents of carbonate-bearing fluorapatite rocks from the Kovdor, Sokli, Bukusu, Catalão I and Glenover carbonatites in order to further understand their origin, as well as to comment upon the concentration of elements that may be deleterious to fertiliser production. The paragenesis of apatite from each deposit is broadly equivalent, comprising residual magmatic grains overgrown by several different stages of carbonate-bearing fluorapatite. The first forms epitactic overgrowths on residual magmatic grains, followed by the formation of massive apatite which, in turn, is cross-cut by late euhedral and colloform apatite generations. Compositionally, the paragenetic sequence corresponds to a substantial decrease in the concentration of rare earth elements (REE), Sr, Na and Th, with an increase in U and Cd. The carbonate-bearing fluorapatite exhibits a negative Ce anomaly, attributed to oxic conditions in a surficial environment and, in combination with the textural and compositional commonality, supports a weathering origin for these rocks. Carbonate-bearing fluorapatite has Th contents which are several orders of magnitude lower than magmatic apatite grains, potentially making such apatite a more environmentally attractive feedstock for the fertiliser industry. Uranium and cadmium contents are higher in carbonate-bearing fluorapatite than magmatic carbonatite apatite, but are much lower than most marine phosphorites

Quality of Life in children and young people with congenital adrenal hyperplasia—UK nationwide multicenter assessment

Context Quality of life (QoL) has been inconsistently reported in children and young people (CYP) with congenital adrenal hyperplasia (CAH). Objective Assess QoL in CYP with CAH in the UK alongside biometric and androgen profiles. Design To define the evidence base for health care delivery, we conducted a cross-sectional study in CYP with CAH in the UK. Questionnaire results were compared with normative data and between groups, and modelled for association with sex, height, weight, body mass index, or steroid biomarkers of CAH control. Setting Tertiary care in 14 UK centers. Patients Results from 104 patients, 55% female, mean age 12.7 years (SD 3.0), paired responses from parents. Interventions Strengths and Difficulties questionnaire (SDQ) and pediatric QoL questionnaire. Main Outcome Measure Total QoL scores as assessed by SDQ and a pediatric QoL questionnaire in comparison to normative data. Results Total scores were worse in parents than normative data, but similar in patients. Patient QoL was rated better in social functioning but worse in emotional, school, and peer domains by patients, and worse in total scores and domains of peer problems, and psychosocial, emotional, and school functioning by parents. Parents consistently scored QoL of their children lower than their child. Larger height-SD score and lower weight-SD score were associated with better QoL. Girls with lower steroid biomarkers had worse SDQ scores. Conclusions In CYP with CAH, reduced height, increased weight, and hormonal biomarkers consistent with overtreatment were associated with worse QoL; addressing these problems should be prioritized in clinical management