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 possible involvement of topogenic export sequences within the colicin A polypeptide chain has been investigated. Different constructs have been made using various techniques to introduce deletions in the central and NH2-terminal regions of colicin A. Together, these deletions span the region from amino acid 15 to the end of the protein. None of these regions was found to be required for extracellular release or had any effect on the efficiency of this process. By inserting a termination codon, a Shine-Dalgarno sequence and an initiation codon into the gene for colicin A, the NH2-terminal and central plus COOH-terminal domains could be demonstrated to be released to the same extent when produced as separate polypeptides as when produced as linked ones. The introduction into the COOH-terminal domain of mutations promoting cytoplasmic aggregation had no effect on the secretion of the NH2-terminal polypeptide. These results demonstrated that no specific interaction between the NH2- and COOH-terminal regions of the colicin A polypeptide chain is involved in the release of colicin A. We are led to conclude that there is no topogenic export signal in the polypeptide chain of colicin A involved in the release mechanism. Thus the process is non-specific with respect to the colicin itself and depends solely on the expression of the colicin A lysis protein (Cavard et al., 1985, 1987). The expression of the protein causes the release of not only the colicin but also many other cellular proteins, including beta-lactamase, EF-Tu, and chloramphenicol acetyltransferase.
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PMID:Extracellular release of colicin A is non-specific. 331 27

The complete primary structure of the str operon of Bacillus stearothermophilus was determined. It was established that the operon is a five-gene transcriptional unit: 5'-ybxF (unknown function; homology to eukaryotic ribosomal protein L30)-rpsL (S12)-rpsG (S7)-fus (elongation factor G [EF-G])-tuf (elongation factor Tu [EF-Tu])-3'. The main operon promoter (strp) was mapped upstream of ybxF, and its strength was compared with the strength of the tuf-specific promoter (tufp) located in the fus-tuf intergenic region. The strength of the tufp region to initiate transcription is about 20-fold higher than that of the strp region, as determined in chloramphenicol acetyltransferase assays. Deletion mapping experiments revealed that the different strengths of the promoters are the consequence of a combined effect of oppositely acting cis elements, identified upstream of strp (an inhibitory region) and tufp (a stimulatory A/T-rich block). Our results suggest that the oppositely adjusted core promoters significantly contribute to the differential expression of the str operon genes, as monitored by the expression of EF-Tu and EF-G.
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PMID:Cloning and characterization of the str operon and elongation factor Tu expression in Bacillus stearothermophilus. 1102 32