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Insights into Modular Polyketide Synthase Loops Aided by Repetitive Sequences
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  • Melissa Hirsch,
  • Kaan Kumru,
  • Ronak Desai,
  • Brendan Fitzgerald,
  • Takeshi Miyazawa,
  • Katherine Ray,
  • Nisha Saif,
  • Samantha Spears,
  • Adrian Keatinge-Clay
Melissa Hirsch
The University of Texas at Austin
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Kaan Kumru
The University of Texas at Austin
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Ronak Desai
The University of Texas at Austin
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Brendan Fitzgerald
The University of Texas at Austin
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Takeshi Miyazawa
The University of Texas at Austin
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Katherine Ray
The University of Texas at Austin
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Nisha Saif
The University of Texas at Austin
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Samantha Spears
The University of Texas at Austin
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Adrian Keatinge-Clay
The University of Texas at Austin
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Abstract

The loops of modular polyketide synthases (PKSs) serve diverse functions but are largely uncharacterized. They frequently contain amino acid repeats resulting from genetic events such as slipped-strand mispairing. Determining the tolerance of loops to amino acid changes would aid in understanding and engineering these multidomain molecule factories. Here, tandem repeats in the DNA encoding 949 modules within 129 cis-acyltransferase PKSs were catalogued, and the locations of the corresponding amino acids within the module were identified. The most frequently inserted interdomain loop corresponds with the updated module boundary immediately downstream of the ketosynthase (KS), while the loops bordering the dehydratase (DH) were nearly intolerant to such insertions. An analysis of the loops bordering the acyl carrier protein (ACP) reveals they are relatively short (14±6 residues), that they resist large increases in length, and that ACP may rely on acyltransferase (AT) accessing a conformation like that observed through electron microscopy of the pikromycin PKS. From the 949 modules, no repetitive sequence loop insertions are located within ACP, and only 2 reside within KS, indicating the sensitivity of these domains to alteration.

Peer review status:UNDER REVIEW

25 Aug 2020Submitted to PROTEINS: Structure, Function, and Bioinformatics
26 Aug 2020Assigned to Editor
26 Aug 2020Submission Checks Completed
16 Sep 2020Reviewer(s) Assigned