4Q1K

Structure and mechanism of a dehydratase/decarboxylase enzyme couple involved in polyketide beta-branching

Summary for 4Q1K

• Entry DOI: 10.2210/pdb4q1k/pdb
• Related: 4Q1G 4Q1H 4Q1I 4Q1J
• Descriptor: polyketide biosynthesis enoyl-CoA isomerase PksI, GLYCEROL, PHOSPHATE ION, ... (4 entities in total)
• Functional Keywords: decarboxylase, lyase
• Biological source: Bacillus subtilis
• Cellular location: Cytoplasm : P40802
• Total number of polymer chains: 3
• Total formula weight: 90699.78

Authors

Nair, A.V.,Race, P.R.,Till, M. (deposition date: 2014-04-03, release date: 2015-05-06, Last modification date: 2024-05-22)

Primary citation

Nair, A.V.,Robson, A.,Ackrill, T.D.,Till, M.,Byrne, M.J.,Back, C.R.,Tiwari, K.,Davies, J.A.,Willis, C.L.,Race, P.R.
Structure and mechanism of a dehydratase/decarboxylase enzyme couple involved in polyketide beta-methyl branch incorporation.
Sci Rep, 10:15323-15323, 2020

PubMed Abstract: Complex polyketides of bacterial origin are biosynthesised by giant assembly-line like megaenzymes of the type 1 modular polyketide synthase (PKS) class. The trans-AT family of modular PKSs, whose biosynthetic frameworks diverge significantly from those of the archetypal cis-AT type systems represent a new paradigm in natural product enzymology. One of the most distinctive enzymatic features common to trans-AT PKSs is their ability to introduce methyl groups at positions β to the thiol ester in the growing polyketide chain. This activity is achieved through the action of a five protein HCS cassette, comprising a ketosynthase, a 3-hydroxy-3-methylglutaryl-CoA synthase, a dehydratase, a decarboxylase and a dedicated acyl carrier protein. Here we report a molecular level description, achieved using a combination of X-ray crystallography, in vitro enzyme assays and site-directed mutagenesis, of the bacillaene synthase dehydratase/decarboxylase enzyme couple PksH/PksI, responsible for the final two steps in β-methyl branch installation in this trans-AT PKS. Our work provides detailed mechanistic insight into this biosynthetic peculiarity and establishes a molecular framework for HCS cassette enzyme exploitation and manipulation, which has future potential value in guiding efforts in the targeted synthesis of functionally optimised 'non-natural' natural products.

PubMed: 32948786
DOI: 10.1038/s41598-020-71850-w

Experimental method

X-RAY DIFFRACTION (1.75 Å)