A smallest 6 kda metalloprotease, mini-matrilysin, in living world: a revolutionary conserved zinc-dependent proteolytic domain- helix-loop-helix catalytic zinc binding domain (ZBD)

Pore engineering as a general strategy to improve protein-based enzyme nanoreactor performance

Enzyme nanoreactors are nanoscale compartments consisting of encapsulated enzymes and a selectively permeable barrier. Sequestration and co-localization of enzymes can increase catalytic activity, stability, and longevity, highly desirable features for many biotechnological and biomedical applications of enzyme catalysts. One promising strategy to construct enzyme nanoreactors is to repurpose protein nanocages found in nature. However, protein-based enzyme nanoreactors often exhibit decreased catalytic activity, partially caused by a mismatch of protein shell selectivity and the substrate requirements of encapsulated enzymes. No broadly applicable and modular protein-based nanoreactor platform is currently available. Here, we introduce a pore-engineered universal enzyme nanoreactor platform based on encapsulins - microbial self-assembling protein nanocompartments with programmable and selective enzyme packaging capabilities. We structurally characterize our protein shell designs via cryo-electron microscopy and highlight their polymorphic nature. Through fluorescence polarization assays, we show their improved molecular flux behavior and highlight their expanded substrate range via a number of proof-of-concept enzyme nanoreactor designs. This work lays the foundation for utilizing our encapsulin-based nanoreactor platform for future biotechnological and biomedical applications.

Bacterial M10 metallopeptidase as a medicinal target - coordination chemistry of possible metal-based inhibition

Streptococcus pneumoniae is the most frequent cause of fatal bacterial pneumonia infection worldwide. Due to the spreading of antibiotic-resistant pathogens, it is important to search for new therapeutic and prevention strategies against bacterial infections. It is believed that the search for effective inhibitors of bacterial and pathogenic metallopeptidases could be one of the innovative strategies for the design of new antibiotics. Most of them contain zinc in the metal-binding site of the protein, which is a critical component for the biological activity of the enzyme. The main goal of this work is to determine the specificity of the interactions between the binding domain of the metallopeptidase from S. pneumoniae, and Zn(II). Considering the observed inhibitory role of copper towards the metallopeptidases, the next step is to analyze the formation of complexes with Cu(II) and Ni(II). The thermodynamic properties of Zn(II), Cu(II), and Ni(II) complexes were examined by potentiometry, NMR, MS, UV-Vis, CD, and EPR. The results show a similar coordination pattern, HExxHxxxxxH, for all three studied metals below pH 7. Moreover, the primary binding sites were established as the N-terminus in all cases. However, at a pH value of 7.4, the coordination and geometry of the formed complexes differ. The comparison of the stability of the formed complexes reveals that both Cu(II) and Ni(II) are able to displace Zn(II) from its binding site in the whole studied pH range. It opens a discussion on the catalytic zinc ion displacement possibilities by other divalent metal ions and the importance of this process in enzymatic inhibition.

Matrix Metalloprotease-7 Mediates Nucleolar Assembly and Intra-nucleolar Cleaving p53 in Gefitinib-Resistant Cancer Stem Cells

The enlarged distinct bulky-ball-like nucleolus matrix assembly is observed in most cancer stem cells (CSCs); however, the underlying mechanism is largely unknown. We show that matrix metalloproteinase-7 (MMP-7) shedding MUC-1 SEA domain releases MUC-1 C-ter, facilitating the nucleolus trafficking of p53 in gefitinib-resistant lung CSCs. The nucleolus colocalizations of p53, MUC-1 C-ter, MMP-7 and nucleolin were observed in the CD34⁺ CXADR⁺ CD44v₃⁺ gefitinib-resistant EGFR^L858R/T790M CSC colonies. MUC-1 C-ter induced a unique porous bulky-ball-shaped, cagelike nucleolus that functions as a nucleus molecular “garage” for potent tumor suppressor, p53. Nucleolus could also facilitate the novel sub-nucleus compartment for proteolytic processing p53 by MMP-7 to generate a 35 kDa fragment. Moreover, we show that salinomycin, an anti-CSC agent, disrupts nucleolus by inducing nucleoplasm translocation of p53 and sensitizing CSC to chemotherapy drugs. Thus, this study highlights the MMP-7-MUC-1-p53 axis in nucleolus as a potential therapeutic target for anti-CSCs to resolve the chemotherapy-resistance dilemma.

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MMP-7 cleaves the SEA domain of MUC-1 and releases MUC-1 C-ter

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MUC-1 C-ter mediates bulky-ball-like nucleolus assembly trapping p53 in nucleolus

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MMP-7 cleaves p53 to 35 kDa fragments in the nucleolus of gefitinib-resistant CSCs

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Salinomycin induces p53 nucleoplasm translocation sensitizing CSCs to gefitinib