Isolation and Purification of a New Kalimantacin/Batumin-Related Polyketide Antibiotic and Elucidation of Its Biosynthesis Gene Cluster

Abstract

Kal/bat, a polyketide, isolated to high purity (>95%) is characterized by strong and selective antibacterial activity against Staphylococcus species (minimum inhibitory concentration, 0.05 microg/mL), and no resistance was observed in strains already resistant to commonly used antibiotics. The kal/bat biosynthesis gene cluster was determined to a 62 kb genomic region of Pseudomonas fluorescens BCCM_ID9359. The kal/bat gene cluster consists of 16 open reading frames (ORF), encoding a hybrid PKS-NRPS system, extended with trans-acting tailoring functions. A full model for kal/bat biosynthesis is postulated and experimentally tested by gene inactivation, structural confirmation (using NMR spectroscopy), and complementation. The structural and microbiological study of biosynthetic kal/bat analogs revealed the importance of the carbamoyl group and 17-keto group for antibacterial activity. The mechanism of self-resistance lies within the production of an inactive intermediate, which is activated in a one-step enzymatic oxidation upon export. The genetic basis and biochemical elucidation of the biosynthesis pathway of this antibiotic will facilitate rational engineering for the design of novel structures with improved activities. This makes it a promising new therapeutic option to cope with multidrug-resistant clinical infections.

Bacterial Biosynthetic Gene Clusters Encoding the Anti-cancer Haterumalide Class of Molecules

“…However, OocU has high similarity to proteins found in PKS clusters that have been shown to be trans-acting flavindependent ERs such as PksE from B. subtilis (81) or BatK from Pseudomonas fluorescens (66). Therefore, we postulate that this ER domain might reduce the ␣,␤,␥,␦-conjugated diene attached to module 8, as shown in Fig.…”

“…S5-S8, the numbering of domains refers to the module number as shown in Fig. 2B) (66). Furthermore the characteristic HGTGT catalytic motif, which is essential for the decarboxylative condensation, is poorly conserved in KS5 (QGMGL), KS10a (EANGS), KS10b (HGASS), KS12 (HATGG), KS14 (HSTGS), and KS15 (HAA/TGM) which may indicate that these domains are not extending the polyketide chain (supplemental Fig.…”

Prospects of a new antistaphylococcal drug batumin revealed by molecular docking and analysis of the complete genome sequence of the batumin-producer Pseudomonas batumici UCM B-321

“…Operon of biosynthesis of batumin/kalimantacin in P. fluorescens BCCM_ID9359 was known from previous publications [5,9]. Exactly the same operon of 74,151 bp was found in P. batumici UCM B-321.…”

“…Both batumin and mupirocin are encoded by large hybrid PKS-NRPS operons sharing some level of sequence similarity [3,5]. A common chemical property of mupirocin and batumin is 9-hydroxy-nonanoic acid residue present in their structures.…”

“…Pseudomonas batumici UCM B-321 [2], P.fluorescens BCCM_ID9359 [5] and Alcaligenes sp. YL-02632S [6].…”