scholarly journals Functional role of residues involved in substrate binding of human 4-hydroxyphenylpyruvate dioxygenase

2021 ◽  
Author(s):  
Chih-Wei Huang ◽  
Chi-Ching Hwang ◽  
Yung-Lung Chang ◽  
Jen-Tzu Liu ◽  
Sheng-Peng Wu ◽  
...  
Keyword(s):  
Binding Affinity ◽  
Functional Role ◽  
Substrate Binding ◽  
Critical Role ◽  
Intermediate Formation ◽  
Hydroxyl Group ◽  
Double Mutation ◽  
Closed Conformation ◽  
Bond Network

4-Hydroxylphenylpyruvate dioxygenase (HPPD) catalyzes the conversion of 4-hydroxylphenylpyruvate (HPP) to homogentisate, the important step for tyrosine catabolism. Comparison of the structure of human HPPD with the substrate-bound structure of A. thaliana HPPD revealed notably different orientations of the C-terminal helix. This helix performed as a closed conformation in human enzyme. Simulation revealed a different substrate-binding mode in which the carboxyl group of HPP interacted by a H-bond network formed by Gln334, Glu349 (the metal-binding ligand), and Asn363 (in the C-terminal helix). The 4-hydroxyl group of HPP interacted with Gln251 and Gln265. The relative activity and substrate-binding affinity were preserved for the Q334A mutant, implying the alternative role of Asn363 for HPP binding and catalysis. The reduction in kcat/Km of the Asn363 mutants confirmed the critical role in catalysis. Compared to the N363A mutant, the dramatic reduction in the Kd and thermal stability of the N363D mutant implies the side-chain effect in the hinge region rotation of the C-terminal helix. The activity and binding affinity were not recovered by double mutation; however, the 4-hydroxyphenylacetate intermediate formation by the uncoupled reaction of Q334N/N363Q and Q334A/N363D mutants indicated the importance of the H-bond network in the electrophilic reaction. These results highlight the functional role of the H-bond network in a closed conformation of the C-terminal helix to stabilize the bound substrate. The extremely low activity and reduction in Q251E’s Kd suggest that interaction coupled with the H-bond network is crucial to locate the substrate for nucleophilic reaction.

scholarly journals Hyaluronan–CD44 interaction hampers migration of osteoclast-like cells by down-regulating MMP-9

2002 ◽  
Vol 158 (6) ◽  
pp. 1133-1144 ◽  
Author(s):  
Paola Spessotto ◽  
Francesca Maria Rossi ◽  
Massimo Degan ◽  
Raffaele Di Francia ◽  
Roberto Perris ◽  
...  
Keyword(s):  
Cell Migration ◽  
Bone Resorption ◽  
Cell Motility ◽  
Binding Affinity ◽  
Antisense Oligonucleotides ◽  
Substrate Binding ◽  
Down Regulation ◽  
Multinucleated Cells ◽  
Cell Substrate

Osteoclast (OC) precursors migrate to putative sites of bone resorption to form functionally active, multinucleated cells. The preOC FLG 29.1 cells, known to be capable of irreversibly differentiating into multinucleated OC-like cells, displayed several features of primary OCs, including expression of specific integrins and the hyaluronan (HA) receptor CD44. OC-like FLG 29.1 cells adhered to and extensively migrated through membranes coated with fibronectin, vitronectin, and laminins, but, although strongly binding to HA, totally failed to move on this substrate. Moreover, soluble HA strongly inhibited OC-like FLG 29.1 cell migration on the permissive matrix substrates, and this behavior was dependent on its engagement with CD44, as it was fully restored by function-blocking anti-CD44 antibodies. HA did not modulate the cell–substrate binding affinity/avidity nor the expression levels of the corresponding integrins. MMP-9 was the major secreted metalloproteinase used by OC-like FLG 29.1 cells for migration, because this process was strongly inhibited by both TIMP-1 and GM6001, as well as by MMP-9–specific antisense oligonucleotides. After HA binding to CD44, a strong down-regulation of MMP-9 mRNA and protein was detected. These findings highlight a novel role of the HA–CD44 interaction in the context of OC-like cell motility, suggesting that it may act as a stop signal for bone-resorbing cells.

Electrocatalytic hydrodechlorination of 2,4-dichlorophenol over palladium nanoparticles: The critical role of hydroxyl group deprotonation

2019 ◽  
Vol 583 ◽  
pp. 117146 ◽  
Author(s):  
Song Shu ◽  
Wenyang Fu ◽  
Peng Wang ◽  
Wanglai Cen ◽  
Yinghao Chu ◽  
...  
Keyword(s):  
Palladium Nanoparticles ◽  
Critical Role ◽  
Hydroxyl Group

scholarly journals Aromatic Hydroxyl Group Plays a Critical Role in Antibacterial Activity of the Curcumin Analogues

2012 ◽  
Vol 7 (1) ◽  
pp. 1934578X1200700 ◽  
Author(s):  
Mi Kyoung Kim ◽  
Jun Cheol Park ◽  
Youhoon Chong
Keyword(s):  
Antibacterial Activity ◽  
Critical Role ◽  
Antibacterial Activities ◽  
Structure Activity Relationship ◽  
Activity Relationship ◽  
Hydroxyl Group ◽  
Curcumin Analogues ◽  
Structure Activity ◽  
Relationship Study

The aim of this study was to investigate the role of the aromatic substituents of the curcumin scaffold on the antibacterial activity of the resulting curcumin analogues. Six curcumin analogues with different aromatic substituents were prepared and their antibacterial activities were evaluated against two Gram-positive and four Gram-negative bacteria. The structure-activity relationship study demonstrated that antibacterial activity of the curcumin analogues was critically dependent upon the aromatic hydroxyl group. Thus, hydroxycurcumin with an additional aromatic hydroxyl group on the curcumin scaffold showed antibacterial activity against all six pathogens tested and it remained effective even against ampicillin-resistant Enterobacter cloacae. Along with the previously reported antioxidative effect, the broad-spectrum antibacterial activity of the hydroxycurcumin warrants further investigation of its biological activity as well as extensive structure-activity relationship study of the curcumin analogues with various aromatic substituents.

scholarly journals Upregulation of LncDQ is Associated with Poor Prognosis and Promotes Tumor Progression via Epigenetic Regulation of the EMT Pathway in HCC

2018 ◽  
Vol 46 (3) ◽  
pp. 1122-1133 ◽  
Author(s):  
Bing Zeng ◽  
Zewei Lin ◽  
Huilin Ye ◽  
Di Cheng ◽  
Guangtao Zhang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Functional Role ◽  
Epithelial Mesenchymal Transition ◽  
Critical Role ◽  
Migration And Invasion ◽  
Mesenchymal Transition ◽  
Hcc Cells

Background/Aims: Long noncoding RNAs (lncRNAs) are key regulators of cancer initiation and progression. In this study, we investigated the clinical value and functional role of LncRNA DQ786243 (LncDQ) in the pathogenesis of hepatocellular carcinoma (HCC). Methods: To investigate the expression level of LncDQ in HCC, we performed quantitative real-time PCR using total RNA extracted from HCC tumor tissues and their matched non-neoplastic counterparts, as well as from the serum of HCC patients and healthy volunteers. The correlation of LncDQ expression with clinicopathologic features and prognosis was analyzed. The functional role of LncDQ in cell proliferation, migration, and invasion were evaluated by MTT cell viability, wound healing, and transwell assays in vitro and in vivo. RNA immunoprecipitation and chromatin immunoprecipitation assays were performed to analyze the potential mechanism of LncDQ in HCC cells. Results: LncDQ was upregulated in both HCC tissue samples and serum and was correlated with low survival rate and adverse clinical pathological characteristics. Multivariate analysis demonstrated that LncDQ expression was an independent prognostic factor for HCC. The area under the receiver operating characteristic curve was 0.804 with a sensitivity of 0.72 and a specificity of 0.8. Knockdown of LncDQ induced inhibition of cell proliferation, migration, and invasion in vitro and in vivo. Mechanistically, LncDQ regulated the epithelial–mesenchymal transition pathway by interacting with EZH2, to epigenetically repress the expression of E-cadherin in HCC cells. Conclusions: Taken together, the results of our study indicate that LncDQ plays a critical role in HCC progression, and may serve as a potential diagnostic and prognostic biomarker for HCC.

scholarly journals Efficient Trafficking of TGN38 from the Endosome to the trans-Golgi Network Requires a Free Hydroxyl Group at Position 331 in the Cytosolic Domain

1998 ◽  
Vol 9 (8) ◽  
pp. 2125-2144 ◽  
Author(s):  
Elizabeth P. Roquemore ◽  
George Banting
Keyword(s):  
Critical Role ◽  
Hydroxyl Group ◽  
Serine Residue ◽  
Trans Golgi Network ◽  
Cytosolic Domain ◽  
Model Protein ◽  
Free Hydroxyl ◽  
Degree Of Participation ◽  
Golgi Network

TGN38 is one of the few known resident integral membrane proteins of the trans-Golgi network (TGN). Since it cycles constitutively between the TGN and the plasma membrane, TGN38 is ideally suited as a model protein for the identification of post-Golgi trafficking motifs. Several studies, employing chimeric constructs to detect such motifs within the cytosolic domain of TGN38, have identified the sequence333YQRL336 as an autonomous signal capable of localizing reporter proteins to the TGN. In addition, one group has found that an upstream serine residue, S331, may also play a role in TGN38 localization. However, the nature and degree of participation of S331 in the localization of TGN38 remain uncertain, and the effect has been studied in chimeric constructs only. Here we investigate the role of S331 in the context of full-length TGN38. Mutations that abolish the hydroxyl moiety at position 331 (A, D, and E) lead to missorting of endocytosed TGN38 to the lysosome. Conversely, mutation of S331 to T has little effect on the endocytic trafficking of TGN38. Together, these findings indicate that the S331 hydroxyl group has a direct or indirect effect on the ability of the cytosolic tail of TGN38 to interact with trafficking and/or sorting machinery at the level of the early endosome. In addition, mutation of S331 to either A or D results in increased levels of TGN38 at the cell surface. The results confirm that S331 plays a critical role in the intracellular trafficking of TGN38 and further reveal that TGN38 undergoes a signal-mediated trafficking step at the level of the endosome.

scholarly journals Functional role of vitronectin in breast cancer

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242141
Author(s):  
Alakesh Bera ◽  
Madhan Subramanian ◽  
John Karaian ◽  
Michael Eklund ◽  
Surya Radhakrishnan ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Functional Role ◽  
Cancer Survival ◽  
Early Stage ◽  
Critical Role ◽  
Breast Cancer Survival ◽  
Breast Cancer Cell Lines ◽  
Breast Cancer Patients ◽  
Serum Samples

Breast Cancer is the most common form of cancer in women worldwide, impacting nearly 2.1 million women each year. Identification of new biomarkers could be key for early diagnosis and detection. Vitronectin, a glycoprotein that is abundantly found in serum, extracellular matrix, and bone, binds to integrin αvβ3, and promotes cell adhesion and migration. Current studies indicate that patients with amplified vitronectin levels have lower survival rates than patients without amplified vitronectin levels. In this study, we focused on the role of vitronectin in breast cancer survival and its functional role as a non-invasive biomarker for early stage and stage specific breast cancer detection. To confirm that the expression of vitronectin is amplified in breast cancer, a total of 240 serum samples (n = 240), 200 from breast cancer patients and 40 controls were analyzed using the Reverse Phase Protein Array (RPPA) technique. Of the 240 samples, 120 samples were of African American (AA) descent, while the other 120 were of White American (WA) descent. Data indicated that there were some possible racial disparities in vitronectin levels and, differences also seen in the recurrent patient samples. Next, we tried to uncover the underlying mechanism which plays a critical role in vitronectin expression. The cellular data from four different breast cancer cell lines- MCF7, MDA-MB-231, MDA-MB-468, and HCC1599 indicated that the PI3K/AKT axis is modulating the expression of vitronectin. We believe that vitronectin concentration levels are involved and connected to the metastasis of breast cancer in certain patients, specifically based on recurrence or ethnicity, which is detrimental for poor prognosis. Therefore, in this current study we showed that the serum vitronectin levels could be an early marker for the breast cancer survival and we also determine the cellular signaling factors which modulate the expression and concentration of vitronectin.

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