Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Biochemical Characteristization of Propionyl-Coenzyme A Carboxylase Complex of Streptomyces toxytricini: Atanas V. Demirev , Anamika Khanal , Nguyen Phan Kieu Hanh , Kyung Tae Nam , Doo Hyun Nam; J. Microbiol. 2011;49(3):407-412. Published online June 30, 2011; DOI: https://doi.org/10.1007/s12275-011-1122-1

Abstract: Acyl-CoA carboxylases (ACC) are involved in important primary or secondary metabolic pathways such as fatty acid and/or polyketides synthesis. In the 6.2 kb fragment of pccB gene locus of Streptomyces toxytricini producing a pancreatic inhibitor lipstatin, 3 distinct subunit genes of presumable propionyl-CoA carboxylase (PCCase) complex, assumed to be one of ACC responsible for the secondary metabolism, were identified along with gene for a biotin protein ligase (Bpl). The subunits of PCCase complex were α subunit (AccA3), β subunit (PccB), and auxiliary ε subunit (PccE). In order to disclose the involvement of the PCCase complex in secondary metabolism, some biochemical characteristics of each subunit as well as their complex were examined. In the test of substrate specificity of the PCCase complex, it was confirmed that this complex showed much higher conversion of propionyl-CoA rather than acetyl-CoA. It implies the enzyme complex could play a main role in the production of methylmalonyl-CoA from propionyl-CoA, which is a precursor of secondary polyketide biosynthesis.

Cloning and Analysis of a Type II Polyketide Synthase Gene Cluster from Streptomyces toxytricini NRRL 15,443: Anna Yoo , Atanas V. Demirev , Ji Seon Lee , Sang Dal Kim , Doo Hyun Nam; J. Microbiol. 2006;44(6):649-654.; DOI: https://doi.org/2462 [pii]

Abstract: A standard type II polyketide synthase (PKS) gene cluster was isolated while attempting to clone the biosynthetic gene for lipstatin from Streptomyces toxytricini NRRL 15,443. This result was observed using a Southern blot of a PstI-digested S. toxytricini chromosomal DNA library with a 444 bp amplified probe of a ketosynthase (KS) gene fragment. Four open reading frames [thioesterase (TE), β-ketoacyl systhase (KAS), chain length factor (CLF), and acyl carrier protein (ACP)], were identified through the nucleotide sequence determination and analysis of a 4.5 kb cloned DNA fragment. In order to confirm the involvement of a cloned gene in lipstatin biosynthesis, a gene disruption experiment for the KS gene was performed. However, the resulting gene disruptant did not show any significant difference in lipstatin production when compared to wild-type S. toxytricini. This result suggests that lipstatin may not be synthesized by a type II PKS.

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