Exploring Protein Interactions on a Minimal Type II Polyketide Synthase Using a Yeast Two-Hybrid System

Gaetano Castaldo1, John Crosby2 and Paul F. Long1*

The School of Pharmacy, University of London, 29/39 Brunswick Square, Bloomsbury, London WC1N 1AX, UK

2The School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, UK

Article history:

Received December 22, 2004
Accepted February 28, 2005

Key words:

Streptomyces, aromatic polyketides, protein interactions, doxorubicin


Interactions between proteins that form the ’minimal’ type II polyketide synthase in the doxorubicin producing biosynthetic pathway from Streptomyces peucetius were investigated using a yeast two-hybrid system (Y2H). Proteins that function as the so called ’chain length factor’ (DpsB) and putative transacylase (DpsD) were found to interact with the ketosynthase subunit (DpsA), which can also interact with itself. On the basis of these results we propose a head-to-tail homodimeric structure, which is consistent with previously published in vivo mutagenesis studies. No interactions were found between the acyl-carrier protein (DpsG) and any of the other constituents of the complex, however, transient interactions, not detectable using the Y2H system, cannot be discounted and warrant further investigation.

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