Hara P. Ghosh
McMaster University
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Featured researches published by Hara P. Ghosh.
The EMBO Journal | 1998
Matthias J. Schnell; Linda Buonocore; Eli Boritz; Hara P. Ghosh; Robert Chernish; John K. Rose
The cytoplasmic domains of viral glycoproteins are often involved in specific interactions with internal viral components. These interactions can concentrate glycoproteins at virus budding sites and drive efficient virus budding, or can determine virion morphology. To investigate the role of the vesicular stomatitis virus (VSV) glycoprotein (G) cytoplasmic and transmembrane domains in budding, we recovered recombinant VSVs expressing chimeric G proteins with the transmembrane and cytoplasmic domains derived from the human CD4 protein. These unrelated foreign sequences were capable of supporting efficient VSV budding. Further analysis of G protein cytoplasmic domain deletion mutants showed that a cytoplasmic domain of only 1 amino acid did not drive efficient budding, whereas 9 amino acids did. Additional studies in agreement with the CD4‐chimera experiments indicated the requirement for a short cytoplasmic domain on VSV G without the requirement for a specific sequence in that domain. We propose a model for VSV budding in which a relatively non‐specific interaction of a cytoplasmic domain with a pocket or groove in the viral nucleocapsid or matrix proteins generates a glycoprotein array that promotes viral budding.
Journal of Molecular Biology | 1967
Hara P. Ghosh; Dieter Söll; H.G. Khorana
Abstract All of the 64 ribotrinucleotides were tested for the binding of fmet-tRNAF to ribosomes. The trinucleotides AUG, GUG, UUG, ACG, CUG, GCG, UGG, UCG and AGG stimulated the binding, the first three giving the maximum effect. The non-formylatable species (met-tRNAM) was recognized by the triplets AUG and GUG. Polypeptide synthesis in Escherichia coli cell-free system at 0.004 m -Mg2+ concentration proceeded only when messengers contained initiator codons; it also required the presence of fmet-tRNAF and additional stimulation was obtained by the addition of a protein fraction isolated from ribosomal washings. Poly r-UG containing repeating dinucleotide sequence directed the synthesis of fmet-(Cys-Val-)n, and the N-terminal sequence was established as fmet-Cys-Val-Poly r-AUG directed polymethionine synthesis required fmet-tRNAF in addition to met-tRNAM needed for the incorporation of internal methionine. At low Mg2+ ion concentration poly r-GUA specifically stimulated the incorporation of valine, dependent on fmet-tRNAF. Although the triplet UUG stimulated the binding of fmet-tRNAF to ribosomes, poly r-UUG failed to stimulate fmet incorporation and no fmet-tRNAF-dependent polypeptide synthesis at 0.004 m -Mg2+ concentration was observed. From these results the triplets AUG, GUG and GUA are concluded to be codons for the initiation of polypeptide chains by fmet-tRNAF.
Oncogene | 2004
Xinliang Mao; Eric Seidlitz; Ray Truant; Mary Hitt; Hara P. Ghosh
The TSLC1 tumor-suppressor gene is silenced in a number of human cancer tissues and cell lines, including lung, prostate, liver, stomach, pancreatic, and breast cancers. Expression of TSLC1 in a non-small-cell lung cancer (NSCLC) cell line A549 suppresses tumorigenicity in nude mice. However, the molecular mechanism of TSLC1 action is not yet elucidated. In the present study, we show that the expression of TSLC1 from a recombinant adenovirus vector (Ad-TSLC1) inhibited cell proliferation and induced apoptosis in the NSCLC cell line A549. We also demonstrated that subcutaneous tumor growth in nude mice induced by A549 cells was suppressed to the extent of 70–80% by intratumoral injection of Ad-TSLC1. Re-expression of TSLC1 also resulted in activation of the apoptotic protease caspase-3, accompanied by the cleavage of its substrate poly (ADP-ribose) polymerase (PARP). The antiproliferative and pro-apoptotic activity of TSLC1 required the presence of the FERM-binding and PDZ-interacting motifs located in the cytoplasmic domain. Our results demonstrate the pro-apoptotic and oncosuppressive activity of TSLC1 protein, and suggest the potential of TSLC1 for gene therapy.
Journal of Virology | 2003
E. Jeetendra; Kakoli Ghosh; Derek Odell; Jin Li; Hara P. Ghosh; Michael A. Whitt
ABSTRACT The glycoprotein (G) of vesicular stomatitis virus (VSV) is responsible for binding of virus to cells and for mediating virus entry following endocytosis by inducing fusion of the viral envelope with the endosomal membrane. The fusion peptide of G is internal (residues 116 to 137) and exhibits characteristics similar to those of other internal fusion peptides, but recent studies have implicated the region adjacent to the transmembrane domain as also being important for G-mediated membrane fusion. Sequence alignment of the membrane-proximal region of G from several different vesiculoviruses revealed that this domain is highly conserved, suggesting that it is important for G function. Mutational analysis was used to show that this region is not essential for G protein oligomerization, transport to the cell surface, or incorporation into virus particles but that it is essential for acid-induced membrane fusion activity and for virus infectivity. Deletion of the 13 membrane-proximal amino acids (N449 to W461) dramatically reduced cell-cell fusion activity and reduced virus infectivity approximately 100-fold, but mutation of conserved aromatic residues (W457, F458, and W461) either singly or together had only modest effects on cell-cell fusion activity; recombinant virus encoding these mutants replicated as efficiently as wild-type (WT) VSV. Insertion of heterologous sequences in the juxtamembrane region completely abolished membrane fusion activity and virus infectivity, as did deletion of residues F440 to N449. The insertion mutants showed some changes in pH-dependent conformational changes and in virus binding, which could partially explain the defects in membrane fusion activity, but all the other mutants were similar to WT G with respect to conformational changes and virus binding. These data support the hypothesis that the membrane-proximal domain contributes to G-mediated membrane fusion activity, yet the conserved aromatic residues are not essential for membrane fusion or virus infectivity.
Biochemical and Biophysical Research Communications | 1970
Kakoli Ghosh; Hara P. Ghosh
Abstract Removal of the base Y adjacent to the anticodon of yeast tRNAPhe changes its coding properties. Modified tRNAPhe responds to the codon UUC better than the codon UUU. The codon UUU can be read efficiently only at higher Mg2+ conc. or in the presence of streptomycin. Binding studies show that the unmodified and the modified tRNAPhe can not occur next to each other on the two binding sites of a ribosome. Removal of Y changes the configuration of the anticodon loop of tRNAPhe such that the base (G) involved in “Wobble” changes its relative orientation to the other bases in the anticodon.
Journal of Biological Chemistry | 2005
Mari Masuda; Shinji Kikuchi; Tomoko Maruyama; Mika Sakurai-Yageta; Yuko N. Williams; Hara P. Ghosh; Yoshinori Murakami
The tumor suppressor in lung cancer 1 (TSLC1/IGSF4) encodes an immunoglobulin-superfamily cell adhesion molecule whose cytoplasmic domain contains a protein 4.1-binding motif (protein 4.1-BM) and a PDZ-binding motif (PDZ-BM). Loss of TSLC1 expression is frequently observed in advanced cancers implying its involvement in tumor invasion and/or metastasis. Using Madin-Darby canine kidney cells expressing a full-length TSLC1 or various cytoplasmic deletion mutants of TSLC1, we examined the role of TSLC1 in epithelial mesenchymal transitions during the hepatocyte growth factor (HGF)-induced tubulogenesis and cell scattering. In a three-dimensional culture, the full-length TSLC1, which was localized to the lateral membrane of Madin-Darby canine kidney cysts, inhibited HGF-induced tubulogenesis. In contrast, the mutants lacking either the protein 4.1-BM or the PDZ-BM abolished the inhibitory effect on tubulogenesis. In addition, these mutants showed aberrant subcellular localization indicating that lateral localization is correlated with the effect of TSLC1. In a two-dimensional culture, the full-length TSLC1, but not the mutants lacking the protein 4.1-BM or the PDZ-BM, suppressed HGF-induced cell scattering. Furthermore, the cells expressing full-length TSLC1 retained E-cadherin-based cell-cell adhesion even after being treated with HGF. These cells showed prolonged activation of Rac and low activity of Rho, whereas the HGF-treated parental cells induced transient activation of Rac and sustained activation of Rho. Prolonged Rac activation caused by the expression of TSLC1 required its cytoplasmic tail. These findings, taken together, suggest that TSLC1 plays a role in suppressing induction of epithelial mesenchymal transitions by regulating the activation of small Rho GTPases.
Virology | 1989
Paul S. Masters; Resham S. Bhella; Martin Butcher; Bharat Patel; Hara P. Ghosh; Amiya K. Banerjee
A cDNA copy of the mRNA for the glycoprotein G of Chandipura virus, a rhabdovirus, has been cloned, sequenced, and expressed in mammalian cells. The deduced amino acid sequence of G shows that the encoded protein is a typical transmembrane glycoprotein of 524 amino acids containing a cleavable amino-terminal signal peptide, two potential N-linked glycosylation sites, a hydrophobic membrane anchor domain near the carboxy terminus, and a cytoplasmic domain at the carboxy terminus. Somewhat unusual is the appearance of two charged amino acid residues, aspartate and arginine, within the putative membrane anchor sequence. Expression of the G gene in COS cells resulted in production of a glycosylated protein of mol wt 71,000 which was recognized by anti-Chandipura antibodies. Like the viral G protein, the expressed G contained covalently linked palmitic acid. However, unlike its vesicular stomatitis virus (Indiana serotype) counterpart, the Chandipura G protein has no potential palmitate-accepting cysteine residue within its cytoplasmic domain. Thus, the covalent attachment of fatty acid to this molecule may occur at one or both of the cysteines within the membrane anchor domain. The G protein was intracellularly transported to the cell surface and could induce cell fusion at low pH, showing that the expressed G protein was biologically active.
Virology | 2003
Yi Yao; Kakoli Ghosh; Raquel F. Epand; Richard M. Epand; Hara P. Ghosh
The fusogenic envelope glycoprotein G of the rhabdovirus vesicular stomatitis virus (VSV) induces membrane fusion at acidic pH. At acidic pH the G protein undergoes a major structural reorganization leading to the fusogenic conformation. However, unlike other viral fusion proteins, the low-pH-induced conformational change of VSV G is completely reversible. As well, the presence of an alpha-helical coiled-coil motif required for fusion by a number of viral and cellular fusion proteins was not predicted in VSV G protein by using a number of algorithms. Results of pH dependence of the thermal stability of G protein as determined by intrinsic Trp fluorescence and circular dichroism (CD) spectroscopy show that the G protein is equally stable at neutral or acidic pH. Destabilization of G structure at neutral pH with either heat or urea did not induce membrane fusion or conformational change(s) leading to membrane fusion. Taken together, these data suggest that the mechanism of VSV G-induced fusion is distinct from the fusion mechanism of fusion proteins that involve a coiled-coil motif.
Biochemical and Biophysical Research Communications | 1971
Kakoli Ghosh; A. Grishko; Hara P. Ghosh
Abstract The two major species of tRNAMet from wheat germ have been purified and studied for their role in protein synthesis. tRNA1Met can be charged both by wheat embryo synthetase and E. coli synthetase and tRNA2Met can be charged only by wheat embryo synthetase. Methionyl-tTNA1Met fails to transfer methionine into a polypeptide chain while met-tRNA2Met can transfer methionine into a polypeptide chain. At low Mg+2 concentration the transfer of methionine from met-tRNA2Met is dependent on the incorporation of methionine from met-tRNA1Met at the N-terminal position.
Journal of General Virology | 1999
Essam Wanas; Sue Efler; Kakoli Ghosh; Hara P. Ghosh
Glycoprotein gB is the most highly conserved glycoprotein in the herpesvirus family and plays a critical role in virus entry and fusion. Glycoprotein gB of herpes simplex virus type 1 contains a hydrophobic stretch of 69 aa near the carboxy terminus that is essential for its biological activity. To determine the role(s) of specific amino acids in the carboxy-terminal hydrophobic region, a number of amino acids were mutagenized that are highly conserved in this region within the gB homologues of the family HERPESVIRIDAE: Three conserved residues in the membrane anchor domain, namely A786, A790 and A791, as well as amino acids G743, G746, G766, G770 and P774, that are non-variant in Herpesviridae, were mutagenized. The ability of the mutant proteins to rescue the infectivity of the gB-null virus, K082, in trans was measured by a complementation assay. All of the mutant proteins formed dimers and were incorporated in virion particles produced in the complementation assay. Mutants G746N, G766N, F770S and P774L showed negligible complementation of K082, whereas mutant G743R showed a reduced activity. Virion particles containing these four mutant glycoproteins also showed a markedly reduced rate of entry compared to the wild-type. The results suggest that non-variant residues in the carboxy-terminal hydrophobic region of the gB protein may be important in virus infectivity.