Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of the simian immunodeficiency virus (SIV) nef gene in viral replication was investigated in several tissue culture systems. SIVmac1A11 is a molecularly cloned virus which replicates in both peripheral blood mononuclear cells (PBMC) and macrophages, although no disease is observed in infected rhesus macaques. In this report, we demonstrate that SIVmac1A11 contains a full open reading frame for nef which specifies a 37-kDa protein. To investigate the effects of nef on viral replication, a 70-bp deletion was introduced into the nef gene of SIVmac1A11. Analysis of infected cell extracts by immunoblotting revealed that both SIVmac1A11 and nef deletion virus SIVmac1A11 delta nef produced the same viral proteins, except that Nef was absent in the mutant virus. The deletion mutation did not affect viral replication in PBMC, in monocyte-derived and alveolar macrophages obtained from rhesus macaques, and in human cell lines HUT-78 and CEMx-174. In addition, SIVmac1A11 and SIVmac1A11 delta nef exhibited similar patterns of cytopathologic changes and ultrastructural appearances in infected cells. SIVmac1A11 and SIVmac1A11 delta nef did not infect human tumor macrophage cell line U937, GCT, THP-1, or HL-60 cells, although virus was produced after these cells were transfected with either wild-type or nef mutant viral DNA. Similar levels of virus were recovered from U937 and THP-1 cells transfected with mutant and parental proviral DNAs. In transient expression assays in a T-cell line and a macrophage line, the nef protein of SIVmac1A11 did not significantly suppress or enhance expression of the chloramphenicol acetyltransferase reporter gene linked to the SIVmac long terminal repeat. Thus, abrogation of nef did not affect several in vitro properties of SIVmac1A11, including patterns of viral infection in rhesus PBMC, rhesus macrophages, or human T-cell lines.
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PMID:The nef gene of simian immunodeficiency virus SIVmac1A11. 150 Dec 82

An initiator tRNA gene, metA, and a closely linked fragment of a second initiator-tRNA-like sequence, metB, from Mycobacterium tuberculosis H37Ra have been cloned and characterized. The promoter region of metA shows the presence of conserved sequence elements, TAGCCT and TTGGCG, with resemblance to -10 and -35 promoter regions. The deduced sequence of the mature tRNA contains the three unique features of the eubacterial initiator tRNAs represented by (i) a C:U mismatch at position 1:72, (ii) three consecutive base pairs, 29-31G:C39-41 in the anticodon stem, and (iii) a purine:pyrimidine (A:U) base pair at position 11:24 in the dihydrouridine stem. A putative hairpin structure consisting of an 11 bp stem and a three-base loop found in the 3' flanking region is followed by a stretch of T residues and may serve as a transcription terminator. Analysis of the expression of metA and of its promoter using chloramphenicol acetyltransferase fusion constructs in Mycobacterium smegmatis shows that metA is a functional gene driven by a strong promoter. Furthermore, the overexpressed transcripts are fully processed and formylated in vivo. The metB clone shows the presence of sequences corresponding to those downstream of position 30 of the tRNA. However, the CCA sequence at the 3' end has been mutated to CCG. Interestingly, the 3' flanking sequences of both the genes are rich in GCT repeats. The metB locus also harbours a repeat element, IS6110. A method to prepare total RNA from mycobacteria (under acidic conditions) to analyse in vivo status of tRNAs is described.
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PMID:Characterization of the initiator tRNA gene locus and identification of a strong promoter from Mycobacterium tuberculosis. 938 37