Biomaterial Database

The gene cluster for chloramphenicol biosynthesis in Streptomyces venezuelae ISP5230 includes novel shikimate pathway homologues and a monomodular non-ribosomal peptide synthetase gene. 2001

J He, and N Magarvey, and M Piraee, and L C Vining

Department of Biology, Dalhousie University, Halifax, Nova Scotia, CanadaB3H 4J11.

Regions of the Streptomyces venezuelae ISP5230 chromosome flanking pabAB, an amino-deoxychorismate synthase gene needed for chloramphenicol (Cm) production, were examined for involvement in biosynthesis of the antibiotic. Three of four ORFs in the sequence downstream of pabAB resembled genes involved in the shikimate pathway. BLASTX searches of GenBank showed that the deduced amino acid sequences of ORF3 and ORF4 were similar to proteins encoded by monofunctional genes for chorismate mutase and prephenate dehydrogenase, respectively, while the sequence of the ORF5 product resembled deoxy-arabino-heptulosonate-7-phosphate (DAHP) synthase, the enzyme that initiates the shikimate pathway. A relationship to Cm biosynthesis was indicated by sequence similarities between the ORF6 product and membrane proteins associated with Cm export. BLASTX searches of GenBank for matches with the translated sequence of ORF1 in chromosomal DNA immediately upstream of pabAB did not detect products relevant to Cm biosynthesis. However, the presence of Cm biosynthesis genes in a 7.5 kb segment of the chromosome beyond ORF1 was inferred when conjugal transfer of the DNA into a blocked S. venezuelae mutant restored Cm production. Deletions in the 7.5 kb segment of the wild-type chromosome eliminated Cm production, confirming the presence of Cm biosynthesis genes in this region. Sequencing and analysis located five ORFs, one of which (ORF8) was deduced from BLAST searches of GenBank, and from characteristic motifs detected in alignments of its deduced amino acid sequence, to be a monomodular nonribosomal peptide synthetase. GenBank searches did not identify ORF7, but matched the translated sequences of ORFs 9, 10 and 11 with short-chain ketoreductases, the ATP-binding cassettes of ABC transporters, and coenzyme A ligases, respectively. As has been shown for ORF2, disrupting ORF3, ORF7, ORF8 or ORF9 blocked Cm production.

UI	MeSH Term	Description	Entries
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D002701	Chloramphenicol	An antibiotic first isolated from cultures of Streptomyces venequelae in 1947 but now produced synthetically. It has a relatively simple structure and was the first broad-spectrum antibiotic to be discovered. It acts by interfering with bacterial protein synthesis and is mainly bacteriostatic. (From Martindale, The Extra Pharmacopoeia, 29th ed, p106)	Cloranfenicol,Kloramfenikol,Levomycetin,Amphenicol,Amphenicols,Chlornitromycin,Chlorocid,Chloromycetin,Detreomycin,Ophthochlor,Syntomycin
D003001	Cloning, Molecular	The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.	Molecular Cloning
D005798	Genes, Bacterial	The functional hereditary units of BACTERIA.	Bacterial Gene,Bacterial Genes,Gene, Bacterial
D005810	Multigene Family	A set of genes descended by duplication and variation from some ancestral gene. Such genes may be clustered together on the same chromosome or dispersed on different chromosomes. Examples of multigene families include those that encode the hemoglobins, immunoglobulins, histocompatibility antigens, actins, tubulins, keratins, collagens, heat shock proteins, salivary glue proteins, chorion proteins, cuticle proteins, yolk proteins, and phaseolins, as well as histones, ribosomal RNA, and transfer RNA genes. The latter three are examples of reiterated genes, where hundreds of identical genes are present in a tandem array. (King & Stanfield, A Dictionary of Genetics, 4th ed)	Gene Clusters,Genes, Reiterated,Cluster, Gene,Clusters, Gene,Families, Multigene,Family, Multigene,Gene Cluster,Gene, Reiterated,Multigene Families,Reiterated Gene,Reiterated Genes
D005816	Genetic Complementation Test	A test used to determine whether or not complementation (compensation in the form of dominance) will occur in a cell with a given mutant phenotype when another mutant genome, encoding the same mutant phenotype, is introduced into that cell.	Allelism Test,Cis Test,Cis-Trans Test,Complementation Test,Trans Test,Allelism Tests,Cis Tests,Cis Trans Test,Cis-Trans Tests,Complementation Test, Genetic,Complementation Tests,Complementation Tests, Genetic,Genetic Complementation Tests,Trans Tests
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000637	Transaminases	A subclass of enzymes of the transferase class that catalyze the transfer of an amino group from a donor (generally an amino acid) to an acceptor (generally a 2-keto acid). Most of these enzymes are pyridoxyl phosphate proteins. (Dorland, 28th ed) EC 2.6.1.	Aminotransferase,Aminotransferases,Transaminase
D001426	Bacterial Proteins	Proteins found in any species of bacterium.	Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial