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Previous work has identified crystallin proteins extracted from fish eye lenses as a cheap and readily available source for the self-assembly of amyloid nanofibrils. However, before exploring potential applications, the biophysical aspects and safety of this bionanomaterial need to be assessed so as to ensure that it can be effectively and safely used. In this study, crude crystallin amyloid fibrils are shown to be stable across a wide pH range, in a number of industrially relevant solvents, at both low and high temperatures, and in the presence of proteases. Crystallin nanofibrils were compared to well characterised insulin and whey protein fibrils using Thioflavin T assays and TEM imaging. Cell cytotoxicity assays suggest no adverse impact of both mature and fragmented crystallin fibrils on cell viability of Hec-1a endometrial cells. An IR microspectroscopy study supports long-term structural integrity of crystallin nanofibrils.

Background: Primary membranous nephropathy (MN) is caused by circulating autoantibodies (ab) binding to antigens on the podocyte surface. PLA2R1 is the main target antigen in 70-80% of cases, but the pathogenesis is unresolved in 10-15% of patients. Methods: We used native Western blotting to identify IgG4-ab in the serum of the index MN patient, which binds an antigen endogenously expressed on podocyte membranes. These IgG4-ab were used to immunoprecipitate the target antigen and mass spectrometry used to identify Netrin G1 (NTNG1). Native Western blot and ELISA analyzed NTNG1-ab in cohorts of 888 patients with MN or other glomerular diseases. Results: NTNG1 was identified as a novel target antigen in MN. It is a membrane protein expressed in healthy podocytes. Immunohistochemistry confirmed granular NTNG1 in subepithelial glomerular immune deposits. In prospective and retrospective MN cohorts, we identified three patients with NTNG1-associated MN, who showed IgG4-dominant circulating NTNG1-ab, enhanced NTNG1 expression in the kidney, and glomerular IgG4 deposits. No NTNG1-ab were identified in 561 PLA2R1-ab positive patients, 27 THSD7A-ab positive patients, and 77 patients with other glomerular diseases. In two patients with available followup of 2 and 4 years, both NTNG1-ab and proteinuria persisted. Conclusions: NTNG1 expands the repertoire of target antigens in patients with MN. The clinical role of NTNG1-ab remains to be defined.

In this paper, we give an overview of our research exploring the impact of physical and chemical processing on food proteins. There are three themes, applied to the proteins of wheat, soya, egg and dairy foods. Firstly, the impact of the Maillard reaction on food proteins is discussed, with a particular focus on how the reactions might be harnessed to manipulate food texture. Secondly, the potential of enzymatic protein-protein crosslinking is considered, especially the enzyme transglutaminase. Thirdly, the broader question of how the aggregation of proteins within a food is altered by chemical and physical modification and how, in turn, this might impact on the overall nutritional quality of the food is considered.

Glutamate racemase (MurI) is responsible for providing D-glutamate for peptidoglycan biosynthesis in bacteria and has been a favoured target in pharmaceutical drug design efforts. It has recently been proven to be essential in Mycobacterium tuberculosis, the causative organism of tuberculosis, a disease for which new medications are urgently needed. In the present study, we have determined the protein crystal structures of MurI from both M. tuberculosis and Mycobacterium smegmatis in complex with D-glutamate to 2.3 Å and 1.8 Å resolution respectively. These structures are conserved, but reveal differences in their active site architecture compared with that of other MurI structures. Furthermore, compounds designed to target other glutamate racemases have been screened but do not inhibit mycobacterial MurI, suggesting that a new drug design effort will be needed to develop inhibitors. A new type of MurI dimer arrangement has been observed in both structures, and this arrangement becomes the third biological dimer geometry for MurI found to date. The mycobacterial MurI dimer is tightly associated, with a KD in the nanomolar range. The enzyme binds D- and L-glutamate specifically, but is inactive in solution unless the dimer interface is mutated. We created triple mutants of this interface in the M. smegmatis glutamate racemase (D26R/R105A/G194R or E) that have appreciable activity (kcat=0.056-0.160 min(-1) and KM=0.26-0.51 mM) and can be utilized to screen proposed antimicrobial candidates for inhibition.

a b s t r a c t b-Lactoglobulin (blg) is the most abundant whey protein in the milks of ruminant animals. While bovine blg has been subjected to a vast array of studies, little is known about the caprine ortholog. We present an ultra-high resolution crystal structure of caprine blg complemented by analytical ultracentrifugation and small-angle X-ray scattering data. In both solution and crystalline states caprine blg is dimeric (K D < 5 lM); however, our data suggest a flexible quaternary arrangement of subunits within the dimer. These structural findings will provide insight into relationships among structural, processing, nutritional and immunological characteristics that distinguish cow's and goat's milk. Structured summary of protein interactions:cBlg and cBlg bind by cosedimentation in solution (View interaction) bBlg and bBlg bind by cosedimentation in solution (View interaction) cBlg and cBlg bind by X ray scattering (View interaction) cBlg and cBlg bind by X-ray crystallography (View interaction)

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