Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.5.1.18 (glutathione S-transferase)
 22,582 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The efficient partitioning of the 2microm plasmid of Saccharomyces cerevisiae at cell division requires two plasmid-encoded proteins (Rep1p and Rep2p) and a cis-acting locus, REP3 (STB). By using protein hybrids containing fusions of the Rep proteins to green fluorescent protein (GFP), we show here that fluorescence from GFP-Rep1p or GFP-Rep2p is almost exclusively localized in the nucleus in a cir+ strain. Nuclear localization of GFP-Rep1p and GFP-Rep2p, though discernible, is less efficient in a cir(0) host. GFP-Rep2p or GFP-Rep1p is able to promote the stability of a 2microm circle-derived plasmid harboring REP1 or REP2, respectively, in a cir(0) background. Under these conditions, fluorescence from GFP-Rep2p or GFP-Rep1p is concentrated within the nucleus, as is the case in cir+ cells. This characteristic nuclear accumulation is not dependent on the expression of the FLP or RAF1 gene of the 2microm circle. Nuclear colocalization of Rep1p and Rep2p is consistent with the hypothesis that the two proteins directly or indirectly interact to form a functional bipartite or high-order protein complex. Immunoprecipitation experiments as well as baiting assays using GST-Rep hybrid proteins suggest a direct interaction between Rep1p and Rep2p which, in principle, may be modulated by other yeast proteins. Furthermore, these assays provide evidence for Rep1p-Rep1p and Rep2p-Rep2p associations as well. The sum of these interactions may be important in controlling the effective cellular concentration of the Rep1p-Rep2p complex.
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PMID:The 2microm-plasmid-encoded Rep1 and Rep2 proteins interact with each other and colocalize to the Saccharomyces cerevisiae nucleus. 939 16

The commercially important bacterium Lactococcus lactis contains two FNR-like proteins (FlpA and FlpB) which have a high degree of identity to each other and to the FLP of Lactobacillus casei. FlpA was isolated from a GST-FlpA fusion protein produced in Escherichia coli. Like FLP, isolated FlpA is a homodimeric protein containing both Zn and Cu. However, the properties of FlpA were more like those of the E. coli oxygen-responsive transcription factor FNR than the FLP of L. casei. As prepared FlpA recognized an FNR site (TTGAT-N4-ATCAA) but not an FLP site (CCTGA-N4-TCAGG) in band-shift assays. In contrast to FLP, DNA binding by FlpA did not require the formation of an intramolecular disulphide bond. However, despite containing only two cysteine residues per monomer, FlpA was able to acquire an FNR-like, oxygen-labile [4Fe 4S] cluster. But, whereas the incorporation of a [4Fe 4S] cluster into FNR enhances interaction with target DNA, it abolished DNA binding by FlpA. An FlpA variant (FlpA') with an N-terminal region designed to be more FLP-like failed to incorporate an iron-sulphur cluster but could now form an intramolecular disulphide. This simple example of protein engineering, converting an oxygen-labile [4Fe 4S] containing FNR-like protein into a dithiol-disulphide FLP-like redox sensor demonstrates the versatility of the basic CRP structure. Attempts to demonstrate an FlpA-based aerobic-anaerobic switch in the heterologous host E. coli were unsuccessful. However, studies with a series of FNR-dependent lac reporter fusions in strains of E. coli expressing flpA or flpB revealed that both homologues were able to activate expression of FNR-dependent promoters in vivo but only when positioned 61 base pairs upstream of the transcription start.
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PMID:Characterization of the Lactococcus lactis transcription factor FlpA and demonstration of an in vitro switch. 1076 Jan 39