Search results for "Protein domain"

The secreted protein acidic and rich in cysteine is a critical mediator of cell death program induced by WIN/TRAIL combined treatment in osteosarcoma…

2015

Abstract Secreted protein acidic and rich in cysteine (SPARC) is a multi-functional protein which modulates cell-cell and cell-matrix interactions. In cancer cells, SPARC behaves as a tumor promoter in a number of tumors, but it can also act as a tumor suppressor factor. Our previous results showed that the synthetic cannabinoid WIN55,212-2 (WIN), a potent cannabinoid receptor agonist, is able to sensitize osteosarcoma MG63 cells to TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis which is accompanied with endoplasmic reticulum (ER)-stress induction and the increase in autophagic markers. In the present investigation, we studied the role of SPARC in WIN/TRAIL-induced apoptosi…

Hetero-oligomerization of Bacillus thuringiensis Cry1A proteins enhance binding to the ABCC2 transporter of Spodoptera exigua

2021

The ATP binding cassette (ABC) transporters are membrane proteins that can act as putative receptors for Cry proteins from Bacillus thuringiensis (Bt) in the midgut of different insects. For the beet armyworm, Spodoptera exigua, ABCC2 and ABCC3 have been found to interact with Cry1A proteins, the main insecticidal proteins used in Bt crops, as well as Bt-based pesticides. The ABCC2 has shown to have specific binding towards Cry1Ac and is involved in the toxic process of Cry1A proteins, but the role of this transporter and how it relates with the Cry1A proteins is still unknown. Here, we have characterized the interactions between the SeABCC2 and the main proteins that bind to the receptor. …

The Stalk Domain of NKp30 Contributes to Ligand Binding and Signaling of a Preassembled NKp30-CD3ζ Complex

2016

The natural cytotoxicity receptor (NCR) NKp30 (CD337) is a key player for NK cell immunosurveillance of infections and cancer. The molecular details of ligand recognition and its connection to CD3ζ signaling remain unsolved. Here, we show that the stalk domain (129KEHPQLGAGTVLLLR143) of NKp30 is very sensitive to sequence alterations, as mutations lead to impaired ligand binding and/or signaling capacity. Surprisingly, the stalk domains of NKp30 and NKp46, another NCR employing CD3ζ for signaling, were not exchangeable without drastic deficiencies in folding, plasma membrane targeting, and/or ligand-induced receptor signaling. Further mutational studies, N-glycosylation mapping, and plasma …

Evolution of Ciona intestinalis Tumor necrosis factor alpha ( Ci TNFα): Polymorphism, tissues expression, and 3D modeling

2017

Although the Tumor necrosis factor gene superfamily seems to be very conserved in vertebrates, phylogeny, tissue expression, genomic and gene organization, protein domains and polymorphism analyses showed that a strong change has happened mostly in invertebrates in which protochordates were a constraint during the immune-molecules history and evolution. RT PCR was used to investigate differential gene expression in different tissues. The expression shown was greater in the pharynx. Single-nucleotide polymorphism has been investigated in Ciona intestinalis Tumor necrosis factor alpha (CiTNFα) mRNA isolated from the pharynx of 30 ascidians collected from Licata, Sicily (Italy), by denaturing …

2020

Hsp70 proteins and their Hsp40 co-chaperones are essential components of cellular chaperone networks in both prokaryotes and eukaryotes. Here, we performed a genetic analysis to define the protein domains required for the key functions of the major Hsp40/DnaJ protein Sll0897 of the cyanobacterium Synechocystis sp. PCC6803. The expression of the N-terminally located J- and G/F-domains is essential and sufficient for the proteins' fundamental in vivo functions, whereas the presence of the full-length protein, containing the C-terminal substrate-binding domains, is crucial under stress conditions.

Cyclins B1, T1, and H differ in their molecular mode of interaction with cytomegalovirus protein kinase pUL97

2019

Human cytomegalovirus (HCMV) is a common β-herpesvirus causing life-long latent infections. HCMV replication interferes with cell cycle regulation in host cells because the HCMV-encoded cyclin-dependent kinase (CDK) ortholog pUL97 extensively phosphorylates the checkpoint regulator retinoblastoma protein. pUL97 also interacts with cyclins B1, T1, and H, and recent findings have strongly suggested that these interactions influence pUL97 substrate recognition. Interestingly, here we detected profound mechanistic differences among these pUL97-cyclin interactions. Our study revealed the following. (i) pUL97 interacts with cyclins B1 and H in a manner dependent on pUL97 activity and HCMV-specifi…

Transmembrane signaling and cytoplasmic signal conversion by dimeric transmembrane helix 2 and a linker domain of the DcuS sensor kinase

2020

Transmembrane (TM) signaling is a key process of membrane-bound sensor kinases. The C4-dicarboxylate (fumarate) responsive sensor kinase DcuS of Escherichia coli is anchored by TM helices TM1 and TM2 in the membrane. Signal transmission across the membrane relies on the piston-type movement of the periplasmic part of TM2. To define the role of TM2 in TM signaling, we use oxidative Cys cross-linking to demonstrate that TM2 extends over the full distance of the membrane and forms a stable TM homodimer in both the inactive and fumarate-activated state of DcuS. An S186xxxGxxxG194 motif is required for the stability and function of the TM2 homodimer. The TM2 helix further extends on the periplas…

Skeletal Dysplasia Mutations Effect on Human Filamins’ Structure and Mechanosensing

2016

AbstractCells’ ability to sense mechanical cues in their environment is crucial for fundamental cellular processes, leading defects in mechanosensing to be linked to many diseases. The actin cross-linking protein Filamin has an important role in the conversion of mechanical forces into biochemical signals. Here, we reveal how mutations in Filamin genes known to cause Larsen syndrome and Frontometaphyseal dysplasia can affect the structure and therefore function of Filamin domains 16 and 17. Employing X-ray crystallography, the structure of these domains was first solved for the human Filamin B. The interaction seen between domains 16 and 17 is broken by shear force as revealed by steered mo…

Identification of a classic nuclear localization signal at the N terminus that regulates the subcellular localization of Rbfox2 isoforms during diffe…

2016

Nuclear localization of the alternative splicing factor Rbfox2 is achieved by a C-terminal nuclear localization signal (NLS) which can be excluded from some Rbfox2 isoforms by alternative splicing. While this predicts nuclear and cytoplasmic localization, Rbfox2 is exclusively nuclear in some cell types. Here, we identify a second NLS in the N terminus of Rbfox2 isoform 1A that is not included in Rbfox2 isoform 1F. Rbfox2 1A isoforms lacking the C-terminal NLS are nuclear, whereas equivalent 1F isoforms are cytoplasmic. A shift in Rbfox2 expression toward cytoplasmic 1F isoforms occurs during epithelial to mesenchymal transition (EMT) and could be important in regulating the activity and fu…

Allosteric Cross-Talk among Spike’s Receptor-Binding Domain Mutations of the SARS-CoV-2 South African Variant Triggers an Effective Hijacking of Huma…

2021

The rapid and relentless emergence of novel highly transmissible SARS-CoV-2 variants, possibly decreasing vaccine efficacy, currently represents a formidable medical and societal challenge. These variants frequently hold mutations on the Spike protein's receptor-binding domain (RBD), which, binding to the angiotensin-converting enzyme 2 (ACE2) receptor, mediates viral entry into host cells. Here, all-atom molecular dynamics simulations and dynamical network theory of the wild-type and mutant RBD/ACE2 adducts disclose that while the N501Y mutation (UK variant) enhances the Spike's binding affinity toward ACE2, the concomitant N501Y, E484K, and K417N mutations (South African variant) aptly ad…