Human immunodeficiency virus (HIV) particles produced in COS-7 cells transfected with HIV type 1 (HIV-i) proviral DNA contain 8 molecules of tRNA3LY' per 2 molecules of genomic RNA and 12 molecules of tRNALys per 2 molecules of genomic RNA. When COS-7 cells are transfected with a plasmid containing both HIV-1 proviral DNA and a human tRNA3LYS gene, there is a large increase in the amount of cytoplasmic tRNA3LYS per microgram of total cellular RNA, and the tRNA3LYS content in the virus increases from 8 to 17 molecules per 2 molecules of genomic RNA. However, the total number of tRNALYS molecules per 2 molecules of genomic RNA remains constant at 20; i.e., the viral tRNAliS content decreases from 12 to 3 molecules per 2 molecules of genomic RNA. All detectable tRNA3YS is aminoacylated in the cytoplasm of infected cells and deacylated in the virus. When COS-7 cells are transfected with a plasmid containing both HlV-1 proviral DNA and a mutant amber suppressor tRNA3YS gene (in which the anticodon is changed from TTT to CTA), there is also a large increase in the relative concentration of cytoplasmic tRNALYS, and the tRNALYS content in the virus
Sulfane sulfur, including polysulfide and persulfide, is a newly identified cellular component present in microorganisms; however, its physiological functions are unclear. Streptomyces coelicolor M145 is a model strain of actinomycetes, which produces several polyketides, including actinorhodin. Herein, we found that both exogenously added and endogenously generated sulfane sulfur increased the actinorhodin production and accelerated spore formation of S. coelicolor M145. This bacterial species carries a natural gene circuit containing four genes that encode a CsoR-like transcription factor (ScCsoR), persulfide dioxygenase (ScPDO), rhodanese and a sulfite transporter, which were shown to be responsible for sensing and removal of excessive sulfane sulfur. ScCsoR was observed to bind to the promoters of the four genes, thus repressing their transcription. Sulfane sulfur modified Cys37 of ScCsoR, and the modified ScCSoR did not bind to the promoters, thereby activating the transcription of ScPDO. The deletion of ScCsoR decreased cellular sulfane sulfur, while the deletion of ScPDO increased its levels. The increased sulfane sulfur promoted actinorhodin production and sporulation. This study unveiled a natural gene circuit for maintaining sulfane sulfur homeostasis in bacteria. Further, we identified the trigger effect of sulfane sulfur on actinorhodin production, presenting a new approach for activating polyketide gene clusters in actinomycetes.
Background-Orofacial granulomatosis (OFG) is a rare chronic inflammatory disorder of unknown causation and is characterised histologically by noncaseating granulomas and aggregates of small lymphocytes. The molecular nature of these T cells is, however, unclear. Aims-To determine the T cell receptor
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