scholarly journals The C-terminal region of human plasma fetuin-B is dispensable for the raised-elephant-trunk mechanism of inhibition of astacin metallopeptidases

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tibisay Guevara ◽  
Hagen Körschgen ◽  
Anna Cuppari ◽  
Carlo Schmitz ◽  
Michael Kuske ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Physiological Role ◽  
Zinc Ion ◽  
Terminal Region ◽  
Elephant Trunk ◽  
Regular Secondary Structure ◽  
Mechanism Of Inhibition ◽  
Human Fertility ◽  
Complex Crystal Structure

Abstract Human fetuin-B plays a key physiological role in human fertility through its inhibitory action on ovastacin, a member of the astacin family of metallopeptidases. The inhibitor consists of tandem cystatin-like domains (CY1 and CY2), which are connected by a linker containing a “CPDCP-trunk” and followed by a C-terminal region (CTR) void of regular secondary structure. Here, we solved the crystal structure of the complex of the inhibitor with archetypal astacin from crayfish, which is a useful model of human ovastacin. Two hairpins from CY2, the linker, and the tip of the “legumain-binding loop” of CY1 inhibit crayfish astacin following the “raised-elephant-trunk mechanism” recently reported for mouse fetuin-B. This inhibition is exerted by blocking active-site cleft sub-sites upstream and downstream of the catalytic zinc ion, but not those flanking the scissile bond. However, contrary to the mouse complex, which was obtained with fetuin-B nicked at a single site but otherwise intact, most of the CTR was proteolytically removed during crystallization of the human complex. Moreover, the two complexes present in the crystallographic asymmetric unit diverged in the relative arrangement of CY1 and CY2, while the two complexes found for the mouse complex crystal structure were equivalent. Biochemical studies in vitro confirmed the differential cleavage susceptibility of human and mouse fetuin-B in front of crayfish astacin and revealed that the cleaved human inhibitor blocks crayfish astacin and human meprin α and β only slightly less potently than the intact variant. Therefore, the CTR of animal fetuin-B orthologs may have a function in maintaining a particular relative orientation of CY1 and CY2 that nonetheless is dispensable for peptidase inhibition.

scholarly journals Crystal structure of theMSMEG_4306gene product fromMycobacterium smegmatis

2018 ◽  
Vol 74 (3) ◽  
pp. 166-173
Author(s):  
Adarsh Kumar ◽  
Subramanian Karthikeyan
Keyword(s):  
Crystal Structure ◽  
Coiled Coil ◽  
Structural Similarity ◽  
Data Bank ◽  
Zinc Ion ◽  
Terminal Region ◽  
Amino Acid Residues ◽  
Secretion Systems ◽  
C Terminus ◽  
Zinc Ribbon

TheMSMEG_4306gene fromMycobacterium smegmatisencodes a protein of unknown function with 242 amino-acid residues that contains a conserved zinc-ribbon domain at its C-terminus. Here, the crystal structure of MSMEG_4306 determined by the single-wavelength anomalous dispersion method using just one zinc ion co-purified with the protein is reported. The crystal structure of MSMEG_4306 shows a coiled-coil helix domain in the N-terminal region and a zinc-ribbon domain in the C-terminal region. A structural similarity search against the Protein Data Bank using MSMEG_4306 as a query revealed two similar structures, namely CT398 fromChlamydia trachomatisand HP0958 fromHelicobacter pylori, although they share only ∼15% sequence identity with MSMEG_4306. Based on comparative analysis, it is predicted that MSMEG_4306 may be involved in secretion systems, possibly by interacting with multiple proteins or nucleic acids.

scholarly journals Crystal structure and functional analysis of human C1ORF123

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5377 ◽  
Author(s):  
Siti Nurulnabila A. Rahaman ◽  
Jastina Mat Yusop ◽  
Zeti-Azura Mohamed-Hussein ◽  
Wan Mohd Aizat ◽  
Kok Lian Ho ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Sequence Similarity ◽  
Physiological Role ◽  
Zinc Ion ◽  
Internal Symmetry ◽  
Chromosome 1 ◽  
Zinc Binding ◽  
Binding Motif ◽  
Functional Studies

Proteins of the DUF866 superfamily are exclusively found in eukaryotic cells. A member of the DUF866 superfamily, C1ORF123, is a human protein found in the open reading frame 123 of chromosome 1. The physiological role of C1ORF123 is yet to be determined. The only available protein structure of the DUF866 family shares just 26% sequence similarity and does not contain a zinc binding motif. Here, we present the crystal structure of the recombinant human C1ORF123 protein (rC1ORF123). The structure has a 2-fold internal symmetry dividing the monomeric protein into two mirrored halves that comprise of distinct electrostatic potential. The N-terminal half of rC1ORF123 includes a zinc-binding domain interacting with a zinc ion near to a potential ligand binding cavity. Functional studies of human C1ORF123 and its homologue in the fission yeast Schizosaccharomyces pombe (SpEss1) point to a role of DUF866 protein in mitochondrial oxidative phosphorylation.

scholarly journals Could β-Lactam Antibiotics Block Humoral Immunity?

2021 ◽  
Vol 12 ◽  
Author(s):  
Cléa Melenotte ◽  
Pierre Pontarotti ◽  
Lucile Pinault ◽  
Jean-Louis Mège ◽  
Christian Devaux ◽  
...  
Keyword(s):  
Immune Response ◽  
Immune Cell ◽  
Opportunistic Infections ◽  
Severe Combined Immunodeficiency ◽  
Physiological Role ◽  
Zinc Ion ◽  
Variable Regions ◽  
The Impact

It has been reported that treatment with β-lactam antibiotics induces leukopenia and candidemia, worsens the clinical response to anticancer immunotherapy and decreases immune response to vaccination. β-lactamases can cleave β-lactam antibiotics by blocking their activity. Two distincts superfamilies of β-lactamases are described, the serine β-lactamases and the zinc ion dependent metallo-β-lactamases. In human, 18 metallo-β-lactamases encoding genes (hMBLs) have been identified. While the physiological role of most of them remains unknown, it is well established that the SNM1A, B and C proteins are involved in DNA repair. The SNM1C/Artemis protein is precisely associated in the V(D)J segments rearrangement, that leads to immunoglobulin (Ig) and T-cell receptor variable regions, which have a crucial role in the immune response. Thus in humans, SNM1C/Artemis mutation is associated with severe combined immunodeficiency characterized by hypogammaglobulinemia deficient cellular immunity and opportunistic infections. While catalytic site of hMBLs and especially that of the SNM1 family is highly conserved, in vitro studies showed that some β-lactam antibiotics, and precisely third generation of cephalosporin and ampicillin, inhibit the metallo-β-lactamase proteins SNM1A & B and the SNM1C/Artemis protein complex. By analogy, the question arises as to whether β-lactam antibiotics can block the SNM1C/Artemis protein in humans inducing transient immunodeficiency. We reviewed here the literature data supporting this hypothesis based on in silico, in vitro and in vivo evidences. Understanding the impact of β-lactam antibiotics on the immune cell will offer new therapeutic clues and new clinical approaches in oncology, immunology, and infectious diseases.

scholarly journals The Crystal Structure of the Zinc Phosphodiesterase from Escherichia coli Provides Insight into Function and Cooperativity of tRNase Z-Family Proteins

2006 ◽  
Vol 188 (4) ◽  
pp. 1607-1614 ◽  
Author(s):  
Brenda Kostelecky ◽  
Ehmke Pohl ◽  
Andreas Vogel ◽  
Oliver Schilling ◽  
Wolfram Meyer-Klaucke
Keyword(s):  
Crystal Structure ◽  
Escherichia Coli ◽  
Metal Binding ◽  
Thermotoga Maritima ◽  
Physiological Role ◽  
E Coli ◽  
Ability To Act ◽  
Trnase Z ◽  
Insight Into

ABSTRACT The elaC gene product from Escherichia coli, ZiPD, is a 3′ tRNA-processing endonuclease belonging to the tRNase Z family of enzymes that have been identified in a wide variety of organisms. In contrast to the elaC homologue from Bacillus subtilis, E. coli elaC is not essential for viability, and although both enzymes process only precursor tRNA (pre-tRNA) lacking a CCA triplet at the 3′ end in vitro, the physiological role of ZiPD remains enigmatic because all pre-tRNA species in E. coli are transcribed with the CCA triplet. We present the first crystal structure of ZiPD determined by multiple anomalous diffraction at a resolution of 2.9 Å. This structure shares many features with the tRNase Z enzymes from B. subtilis and Thermotoga maritima, but there are distinct differences in metal binding and overall domain organization. Unlike the previously described homologous structures, ZiPD dimers display crystallographic symmetry and fully loaded metal sites. The ZiPD exosite is similar to that of the B. subtilis enzyme structurally, but its position with respect to the protein core differs substantially, illustrating its ability to act as a clamp in binding tRNA. Furthermore, the ZiPD crystal structure presented here provides insight into the enzyme's cooperativity and assists the ongoing attempt to elucidate the physiological function of this protein.

scholarly journals Structure of mammalian plasma fetuin-B and its mechanism of selective metallopeptidase inhibition

IUCrJ ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 317-330 ◽  
Author(s):  
Anna Cuppari ◽  
Hagen Körschgen ◽  
Dirk Fahrenkamp ◽  
Carlo Schmitz ◽  
Tibisay Guevara ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Serum Proteins ◽  
Elephant Trunk ◽  
Regular Secondary Structure ◽  
Physiological Relevance ◽  
Active Site Cleft ◽  
Cartilaginous Fishes ◽  
Pleiotropic Functions ◽  
Catalytic Zinc

Mammalian fetuin-A and fetuin-B are abundant serum proteins with pleiotropic functions. Fetuin-B is a highly selective and potent inhibitor of metallopeptidases (MPs) of the astacin family, which includes ovastacin in mammals. By inhibiting ovastacin, fetuin-B is essential for female fertility. The crystal structure of fetuin-B was determined unbound and in complex with archetypal astacin, and it was found that the inhibitor has tandem cystatin-type modules (CY1 and CY2). They are connected by an exposed linker with a rigid, disulfide-linked `CPDCP-trunk', and are followed by a C-terminal region (CTR) with little regular secondary structure. The CPDCP-trunk and a hairpin of CY2 form a bipartite wedge, which slots into the active-site cleft of the MP. These elements occupy the nonprimed and primed sides of the cleft, respectively, but spare the specificity pocket so that the inhibitor is not cleaved. The aspartate in the trunk blocks the catalytic zinc of astacin, while the CY2 hairpin binds through a QWVXGP motif. The CY1 module assists in structural integrity and the CTR is not involved in inhibition, as verified by in vitro studies using a cohort of mutants and variants. Overall, the inhibition conforms to a novel `raised-elephant-trunk' mechanism for MPs, which is reminiscent of single-domain cystatins that target cysteine peptidases. Over 200 sequences from vertebrates have been annotated as fetuin-B, underpinning its ubiquity and physiological relevance; accordingly, sequences with conserved CPDCP- and QWVXGP-derived motifs have been found from mammals to cartilaginous fishes. Thus, the raised-elephant-trunk mechanism is likely to be generally valid for the inhibition of astacins by orthologs of fetuin-B.

Repositioning of Difluorinated Propanediones as Inhibitors of Histone Methyltransferases and their Biological Evaluation in Human Leukemic Cell Lines

2019 ◽  
Vol 18 (13) ◽  
pp. 1892-1899 ◽  
Author(s):  
Tanushree Pal ◽  
Asmita Sharda ◽  
Bharat Khade ◽  
C. Sinha Ramaa ◽  
Sanjay Gupta
Keyword(s):  
Cell Lines ◽  
Physiological Role ◽  
Leukemic Cell ◽  
Docking Studies ◽  
Biological Evaluation ◽  
Leukemic Cell Lines ◽  
Histone Lysine ◽  
Histone Lysine Methyltransferase ◽  
Subsequent Decrease

Background: At present, ‘pharmaco-epigenomics’ constitutes the hope in cancer treatment owing to epigenetic deregulation- a reversible process and playing a role in malignancy. Objective: Chemotherapy has many limitations like host-tissue toxicity, drug resistance. Hence, it is imperative to unearth targets to better treat cancer. Here, we intend to repurpose a set of our previously synthesized difluorinated Propanediones (PR) as Histone lysine Methyltransferase inhibitors (HMTi). Methods: The cell lines of leukemic origin viz. histiocytic lymphoma (U937) and acute T-cell leukemia (JURKAT) were treated with PR-1 to 7 after docking studies with active pocket of HMT. The cell cycle analysis, in vitro methylation and cell proliferation assays were carried out to delineate their physiological role. Results: A small molecule PR-4, at 1 and 10µM, has shown to alter the methylation of histone H3 and H4 in both cell lines. Also, treatment shows an increase in G2/M population and a subsequent decrease in the G0/G1 population in U937. In JURKAT, an increase in both G2/M and S phase population was observed. The sub-G1 population showed a steady rise with increase in dose and prolonged time intervals in U937 and JURKAT cell lines. In SRB assay, the PR showed a cell growth of 42.6 and 53.4% comparable to adriamycin; 44.5 and 53.2% in U937 and JURKAT, respectively. The study suggests that PR-4 could emerge as a potential HMT inhibitor. Conclusion: The molecule PR-4 could be a lead in developing more histone lysine methyltransferases inhibitors with potential to be pro-apoptotic agents.

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