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Biosci Rep. 2016 Nov 22;36(6). pii: e00413. Print 2016 Dec.

Engineering a trifunctional proline utilization A chimaera by fusing a DNA-binding domain to a bifunctional PutA.

Author information

1
Department of Biochemistry, Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68588, U.S.A.
2
Department of Chemistry, University of Missouri-Columbia, Columbia, MO 65211, U.S.A.
3
Protein Technologies and Assays, Research and Development, MilliporeSigma, 2909 Laclede Avenue, St. Louis, MO 63103, U.S.A.
4
Department of Biochemistry, University of Missouri-Columbia, Columbia, MO 65211, U.S.A.
5
Department of Biochemistry, Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE 68588, U.S.A. dbecker3@unl.edu.

Abstract

Proline utilization A (PutA) is a bifunctional flavoenzyme with proline dehydrogenase (PRODH) and Δ1-pyrroline-5-carboxylate (P5C) dehydrogenase (P5CDH) domains that catalyses the two-step oxidation of proline to glutamate. Trifunctional PutAs also have an N-terminal ribbon-helix-helix (RHH) DNA-binding domain and moonlight as autogenous transcriptional repressors of the put regulon. A unique property of trifunctional PutA is the ability to switch functions from DNA-bound repressor to membrane-associated enzyme in response to cellular nutritional needs and proline availability. In the present study, we attempt to construct a trifunctional PutA by fusing the RHH domain of Escherichia coli PutA (EcRHH) to the bifunctional Rhodobacter capsulatus PutA (RcPutA) in order to explore the modular design of functional switching in trifunctional PutAs. The EcRHH-RcPutA chimaera retains the catalytic properties of RcPutA while acquiring the oligomeric state, quaternary structure and DNA-binding properties of EcPutA. Furthermore, the EcRHH-RcPutA chimaera exhibits proline-induced lipid association, which is a fundamental characteristic of functional switching. Unexpectedly, RcPutA lipid binding is also activated by proline, which shows for the first time that bifunctional PutAs exhibit a limited form of functional switching. Altogether, these results suggest that the C-terminal domain (CTD), which is conserved by trifunctional PutAs and certain bifunctional PutAs, is essential for functional switching in trifunctional PutAs.

KEYWORDS:

DNA binding; flavin enzyme; proline metabolism; small-angle X-ray scattering (SAXS)

PMID:
27742866
PMCID:
PMC5293562
DOI:
10.1042/BSR20160435
[Indexed for MEDLINE]
Free PMC Article

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