Efficient secretory production of proline/alanine/serine (PAS) biopolymers in Corynebacterium glutamicum yielding a monodisperse biological alternative to polyethylene glycol (PEG)

Abstract Background PAS biopolymers are recombinant polypeptides comprising the small uncharged l-amino acids Pro, Ala and/or Ser which resemble the widely used poly-ethylene glycol (PEG) in terms of pronounced hydrophilicity. Likewise, their random chain behaviour in physiological solution results...

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Main Authors: L. Friedrich, Y. Kikuchi, Y. Matsuda, U. Binder, A. Skerra
Format: Article
Language:English
Published: BMC 2022-10-01
Series:Microbial Cell Factories
Subjects:
Online Access:https://doi.org/10.1186/s12934-022-01948-5
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author L. Friedrich
Y. Kikuchi
Y. Matsuda
U. Binder
A. Skerra
author_facet L. Friedrich
Y. Kikuchi
Y. Matsuda
U. Binder
A. Skerra
author_sort L. Friedrich
collection DOAJ
description Abstract Background PAS biopolymers are recombinant polypeptides comprising the small uncharged l-amino acids Pro, Ala and/or Ser which resemble the widely used poly-ethylene glycol (PEG) in terms of pronounced hydrophilicity. Likewise, their random chain behaviour in physiological solution results in a strongly expanded hydrodynamic volume. Thus, apart from their use as fusion partner for biopharmaceuticals to achieve prolonged half-life in vivo, PAS biopolymers appear attractive as substitute for PEG—or other poorly degradable chemical polymers—in many areas. As a prerequisite for the wide application of PAS biopolymers at affordable cost, we have established their highly efficient biotechnological production in Corynebacterium glutamicum serving as a well characterized bacterial host organism. Results Using the CspA signal sequence, we have secreted two representative PAS biopolymers as polypeptides with ~ 600 and ~ 1200 amino acid residues, respectively. Both PAS biopolymers were purified from the culture supernatant by means of a simple downstream process in a truly monodisperse state as evidenced by ESI–MS. Yields after purification were up to ≥ 4 g per liter culture, with potential for further increase by strain optimization as well as fermentation and bioprocess development. Beyond direct application as hydrocolloids or to exploit their rheological properties, such PAS biopolymers are suitable for site-specific chemical conjugation with pharmacologically active molecules via their unique terminal amino or carboxyl groups. To enable the specific activation of the carboxylate, without interference by the free amino group, we generated a blocked N-terminus for the PAS(1200) polypeptide simply by introducing an N-terminal Gln residue which, after processing of the signal peptide, was cyclised to a chemically inert pyroglutamyl group upon acid treatment. The fact that PAS biopolymers are genetically encoded offers further conjugation strategies via incorporation of amino acids with reactive side chains (e.g., Cys, Lys, Glu/Asp) at defined positions. Conclusions Our new PAS expression platform using Corynex® technology opens the way to applications of PASylation® technology in multiple areas such as the pharmaceutical industry, cosmetics and food technology.
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spelling doaj.art-39ede33bdaa6465da6a29bc690d202582022-12-22T03:22:27ZengBMCMicrobial Cell Factories1475-28592022-10-0121111110.1186/s12934-022-01948-5Efficient secretory production of proline/alanine/serine (PAS) biopolymers in Corynebacterium glutamicum yielding a monodisperse biological alternative to polyethylene glycol (PEG)L. Friedrich0Y. Kikuchi1Y. Matsuda2U. Binder3A. Skerra4XL-protein GmbHResearch Institute for Bioscience Products & Fine Chemicals, Ajinomoto Co., Inc.Research Institute for Bioscience Products & Fine Chemicals, Ajinomoto Co., Inc.XL-protein GmbHXL-protein GmbHAbstract Background PAS biopolymers are recombinant polypeptides comprising the small uncharged l-amino acids Pro, Ala and/or Ser which resemble the widely used poly-ethylene glycol (PEG) in terms of pronounced hydrophilicity. Likewise, their random chain behaviour in physiological solution results in a strongly expanded hydrodynamic volume. Thus, apart from their use as fusion partner for biopharmaceuticals to achieve prolonged half-life in vivo, PAS biopolymers appear attractive as substitute for PEG—or other poorly degradable chemical polymers—in many areas. As a prerequisite for the wide application of PAS biopolymers at affordable cost, we have established their highly efficient biotechnological production in Corynebacterium glutamicum serving as a well characterized bacterial host organism. Results Using the CspA signal sequence, we have secreted two representative PAS biopolymers as polypeptides with ~ 600 and ~ 1200 amino acid residues, respectively. Both PAS biopolymers were purified from the culture supernatant by means of a simple downstream process in a truly monodisperse state as evidenced by ESI–MS. Yields after purification were up to ≥ 4 g per liter culture, with potential for further increase by strain optimization as well as fermentation and bioprocess development. Beyond direct application as hydrocolloids or to exploit their rheological properties, such PAS biopolymers are suitable for site-specific chemical conjugation with pharmacologically active molecules via their unique terminal amino or carboxyl groups. To enable the specific activation of the carboxylate, without interference by the free amino group, we generated a blocked N-terminus for the PAS(1200) polypeptide simply by introducing an N-terminal Gln residue which, after processing of the signal peptide, was cyclised to a chemically inert pyroglutamyl group upon acid treatment. The fact that PAS biopolymers are genetically encoded offers further conjugation strategies via incorporation of amino acids with reactive side chains (e.g., Cys, Lys, Glu/Asp) at defined positions. Conclusions Our new PAS expression platform using Corynex® technology opens the way to applications of PASylation® technology in multiple areas such as the pharmaceutical industry, cosmetics and food technology.https://doi.org/10.1186/s12934-022-01948-5Disordered polypeptideHydrophilic polymerPASylationPEGPro/Ala/Ser
spellingShingle L. Friedrich
Y. Kikuchi
Y. Matsuda
U. Binder
A. Skerra
Efficient secretory production of proline/alanine/serine (PAS) biopolymers in Corynebacterium glutamicum yielding a monodisperse biological alternative to polyethylene glycol (PEG)
Microbial Cell Factories
Disordered polypeptide
Hydrophilic polymer
PASylation
PEG
Pro/Ala/Ser
title Efficient secretory production of proline/alanine/serine (PAS) biopolymers in Corynebacterium glutamicum yielding a monodisperse biological alternative to polyethylene glycol (PEG)
title_full Efficient secretory production of proline/alanine/serine (PAS) biopolymers in Corynebacterium glutamicum yielding a monodisperse biological alternative to polyethylene glycol (PEG)
title_fullStr Efficient secretory production of proline/alanine/serine (PAS) biopolymers in Corynebacterium glutamicum yielding a monodisperse biological alternative to polyethylene glycol (PEG)
title_full_unstemmed Efficient secretory production of proline/alanine/serine (PAS) biopolymers in Corynebacterium glutamicum yielding a monodisperse biological alternative to polyethylene glycol (PEG)
title_short Efficient secretory production of proline/alanine/serine (PAS) biopolymers in Corynebacterium glutamicum yielding a monodisperse biological alternative to polyethylene glycol (PEG)
title_sort efficient secretory production of proline alanine serine pas biopolymers in corynebacterium glutamicum yielding a monodisperse biological alternative to polyethylene glycol peg
topic Disordered polypeptide
Hydrophilic polymer
PASylation
PEG
Pro/Ala/Ser
url https://doi.org/10.1186/s12934-022-01948-5
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