Molecular characterization of the lincomycin‐production gene cluster of Streptomyces lincolnensis 78‐11

Abstract

The lincomycin (LM)-production gene cluster of the overproducing strain Streptomyces lincolnensis 78-11 was cloned, analysed by hybridization, as well as by DNA sequencing, and compared with the respective genome segments of other lincomycin producers. The lmb/lmr gene cluster is composed of 27 open reading frames with putative biosynthetic or regulatory functions (lmb genes) and three resistance (lmr) genes, two of which, lmrA and lmrC, flank the cluster. A very similar overall organization of the lmb/lmr cluster seems to be conserved in four other LM producers, although the clusters are embedded in non-homologous genomic surroundings. In the wild-type strain (S. lincolnensis NRRL2936), the lmb/lmr-cluster apparently is present only in single copy. However, in the industrial strain S. lincolnensis 78-11 the non-adjacent gene clusters for the production of LM and melanin (melC) both are duplicated on a large (0.45-0.5 Mb) fragment, accompanied by deletion events. This indicates that enhanced gene dosage is one of the factors for the overproduction of LM and demonstrates that large-scale genome rearrangements can be a result of classical strain improvement by mutagenesis. Only a minority of the putative Lmb proteins belong to known protein families. These include members of the gamma-glutamyl transferases (LmbA), amino acid acylases (LmbC), aromatic amino acid aminotransferases (LmbF), imidazoleglycerolphosphate dehydratases (LmbK), dTDP-glucose synthases (LmbO), dTDP-glucose 4,6-dehydratases (LmbM) and (NDP-) ketohexose (or ketocyclitol) aminotransferases (LmbS). In contrast to earlier proposals on the biosynthetic pathway of the C-8 sugar moiety (methylthiolincosaminide), this branch of the LM pathway actually seems to be based on nucleotide-activated sugars as precursors.

Molecular cloning and sequence analysis of the clorobiocin biosynthetic gene cluster: new insights into the biosynthesis of aminocoumarin antibiotics The GenBank accession number for the sequence of cosmid K1F2 is AF329398.

“…It was suggested that LmbU may have a regulatory function, but no experimental evidence is available so far to support this (Peschke et al, 1995).…”

The Substitution of a Single Amino Acid Residue (Ser-116 → Asp) Alters NADP-containing Glucose-Fructose Oxidoreductase ofZymomonas mobilis into a Glucose Dehydrogenase with Dual Coenzyme Specificity

“…The processing site of the GFOR presecretory protein between amino acid residues 52 and 53 is marked by an arrow. MocA and ORF334, putative rhizopine dehydrogenases of Rhizobium meliloti (24); DDP-DH, phtalic acid dehydrogenase from Pseudomonas putida (45); GalDH, galactose dehydrogenase from Pseudomonas fluorescens (46); StrI, putative protein in streptomycin biosynthesis from Streptomyces griseus (47); BvRed, biliverdin reductase from rat kidney (48); IDH, inositol dehydrogenase from B. subtilis (36); LmbZ, putative gene product of lmbZ of lincomycin biosynthesis from Streptomyces lincolnensis (49).…”

Cloning and Characterization of the Biosynthetic Gene Cluster for Tomaymycin, an SJG-136 Monomeric Analog

“…1B), sibiromycin, anthramycin, and tomaymycin is L-tyrosine (3,10). The first two steps of this transformation have been biochemically characterized in the lincomycin A biosynthesis (10,25,26). However, the assignment of the subsequent steps remained difficult due to the lack of significant similarity of the ORFs identified with functionally known enzymes.…”