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Host Protein Synthesis (host + protein_synthesis)
Selected AbstractsA teratocyte gene from a parasitic wasp that is associated with inhibition of insect growth and development inhibits host protein synthesisINSECT MOLECULAR BIOLOGY, Issue 5 2003D. L. Dahlman Abstract After parasitization, some wasps induce hosts prematurely to initiate metamorphic development that is then suspended in a postwandering, prepupal state. Following egression of the parasite larva, the host remains in this developmentally arrested state until death. Teratocytes, cells released at egg hatch from extra-embryonic serosal membranes of some wasp parasites, inhibit growth and development when injected into host larvae independent of other parasite factors (e.g. venom, polydnavirus). Synthesis of some developmentally regulated, abundantly expressed Heliothis virescens host proteins is inhibited in hosts parasitized by Microplitis croceipes and by teratocyte injection. A cDNA encoding a 13.9 kDa protein (TSP14) that inhibited protein synthesis, growth and development was isolated from a protein fraction secreted by teratocytes. TSP14 appears to be responsible, in part, for the teratocyte-mediated inhibition of host growth and development. Interestingly, this cDNA encoded a cysteine-rich amino acid motif similar to that described from Campoletis sonorensis polydnavirus, a mutualistic virus that enables wasp parasitization of lepidopteran larvae. Moreover, TSP14 inhibited protein synthesis in a dose-dependent manner in rabbit reticulocyte lysate and wheat germ extract translation systems. We hypothesize that some wasp parasites inhibit translation as a general means to regulate and redirect lepidopteran host physiology to support endoparasite development. [source] Visualizing and quantifying the differential cleavages of the eukaryotic translation initiation factors eIF4GI and eIF4GII in the enterovirus-infected cellBIOTECHNOLOGY & BIOENGINEERING, Issue 6 2009Yueh-Ying Hsu Abstract Enterovirus (EV) infection has been shown to cause a marked shutoff of host protein synthesis, an event mainly achieved through the cleavages of eukaryotic translation initiation factors eIF4GI and eIF4GII that are mediated by viral 2A protease (2Apro). Using fluorescence resonance energy transfer (FRET), we developed genetically encoded and FRET-based biosensors to visualize and quantify the specific proteolytic process in intact cells. This was accomplished by stable expression of a fusion substrate construct composed of the green fluorescent protein 2 (GFP2) and red fluorescent protein 2 (DsRed2), with a cleavage motif on eIF4GI or eIF4GII connected in between. The FRET biosensor showed a real-time and quantifiable impairment of FRET upon EV infection. Levels of the reduced FRET closely correlated with the cleavage kinetics of the endogenous eIF4Gs isoforms. The FRET impairments were solely attributed to 2Apro catalytic activity, irrespective of other viral-encoded protease, the activated caspases or general inhibition of protein synthesis in the EV-infected cells. The FRET biosensors appeared to be a universal platform for several related EVs. The spatiotemporal and quantitative imaging enabled by FRET can shed light on the protease,substrate behaviors in their normal milieu, permitting investigation into the molecular mechanism underlying virus-induced host translation inhibition. Biotechnol. Bioeng. 2009; 104: 1142,1152. © 2009 Wiley Periodicals, Inc. [source] Mouse hepatitis coronavirus replication induces host translational shutoff and mRNA decay, with concomitant formation of stress granules and processing bodiesCELLULAR MICROBIOLOGY, Issue 9 2007Matthijs Raaben Summary Many viruses, including coronaviruses, induce host translational shutoff, while maintaining synthesis of their own gene products. In this study we performed genome-wide microarray analyses of the expression patterns of mouse hepatitis coronavirus (MHV)-infected cells. At the time of MHV-induced host translational shutoff, downregulation of numerous mRNAs, many of which encode protein translation-related factors, was observed. This downregulation, which is reminiscent of a cellular stress response, was dependent on viral replication and caused by mRNA decay. Concomitantly, phosphorylation of the eukaryotic translation initiation factor 2, was increased in MHV-infected cells. In addition, stress granules and processing bodies appeared, which are sites for mRNA stalling and degradation respectively. We propose that MHV replication induces host translational shutoff by triggering an integrated stress response. However, MHV replication per se does not appear to benefit from the inhibition of host protein synthesis, at least in vitro, since viral replication was not negatively affected but rather enhanced in cells with impaired translational shutoff. [source] Salmonella enterica serovar Typhimurium effectors SopB, SopE, SopE2 and SipA disrupt tight junction structure and functionCELLULAR MICROBIOLOGY, Issue 12 2006Erin C. Boyle Summary Salmonella enterica serovar Typhimurium is a major cause of human gastroenteritis. Infection of epithelial monolayers by S. Typhimurium disrupts tight junctions that normally maintain the intestinal barrier and regulate cell polarity. Tight junction disruption is dependent upon the Salmonella pathogenicity island-1 (SPI-1) type 3 secretion system but the specific effectors involved have not been identified. In this study we demonstrate that SopB, SopE, SopE2 and SipA are the SPI-1-secreted effectors responsible for disruption of tight junction structure and function. Tight junction disruption by S. Typhimurium was prevented by inhibiting host protein geranylgeranylation but was not dependent on host protein synthesis or secretion of host-derived products. Unlike wild-type S. Typhimurium, ,sopB, ,sopE/E2, ,sipA, or ,sipA/sopB mutants, ,sopB/E/E2 and ,sipA/sopE/E2 mutants were unable to increase the permeability of polarized epithelial monolayers, did not disrupt the distribution or levels of ZO-1 and occludin, and did not alter cell polarity. These data suggest that SPI-1-secreted effectors utilize their ability to stimulate Rho family GTPases to disrupt tight junction structure and function. [source] | ||||||||||