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Sanyal A, Zbornik EA, Watson BG, Christoffer C, Ma J, Kihara D, Mattoo S. Kinetic and structural parameters governing Fic-mediated adenylylation/AMPylation of the Hsp70 chaperone, BiP/GRP78. Cell Stress Chaperones 2021; 26:639-656. [PMID: 33942205 PMCID: PMC8275707 DOI: 10.1007/s12192-021-01208-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 04/20/2021] [Accepted: 04/26/2021] [Indexed: 12/11/2022] Open
Abstract
Fic (filamentation induced by cAMP) proteins regulate diverse cell signaling events by post-translationally modifying their protein targets, predominantly by the addition of an AMP (adenosine monophosphate). This modification is called Fic-mediated adenylylation or AMPylation. We previously reported that the human Fic protein, HYPE/FicD, is a novel regulator of the unfolded protein response (UPR) that maintains homeostasis in the endoplasmic reticulum (ER) in response to stress from misfolded proteins. Specifically, HYPE regulates UPR by adenylylating the ER chaperone, BiP/GRP78, which serves as a sentinel for UPR activation. Maintaining ER homeostasis is critical for determining cell fate, thus highlighting the importance of the HYPE-BiP interaction. Here, we study the kinetic and structural parameters that determine the HYPE-BiP interaction. By measuring the binding and kinetic efficiencies of HYPE in its activated (Adenylylation-competent) and wild type (de-AMPylation-competent) forms for BiP in its wild type and ATP-bound conformations, we determine that HYPE displays a nearly identical preference for the wild type and ATP-bound forms of BiP in vitro and preferentially de-AMPylates the wild type form of adenylylated BiP. We also show that AMPylation at BiP's Thr366 versus Thr518 sites differentially affect its ATPase activity, and that HYPE does not adenylylate UPR accessory proteins like J-protein ERdJ6. Using molecular docking models, we explain how HYPE is able to adenylylate Thr366 and Thr518 sites in vitro. While a physiological role for AMPylation at both the Thr366 and Thr518 sites has been reported, our molecular docking model supports Thr518 as the structurally preferred modification site. This is the first such analysis of the HYPE-BiP interaction and offers critical insights into substrate specificity and target recognition.
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Affiliation(s)
- Anwesha Sanyal
- From the Department of Biological Sciences, Purdue University, 915 W. State St., LILY G-227, West Lafayette, IN, 47907, USA
| | - Erica A Zbornik
- From the Department of Biological Sciences, Purdue University, 915 W. State St., LILY G-227, West Lafayette, IN, 47907, USA
| | - Ben G Watson
- From the Department of Biological Sciences, Purdue University, 915 W. State St., LILY G-227, West Lafayette, IN, 47907, USA
| | - Charles Christoffer
- Department of Computer Science, Purdue University, West Lafayette, IN, 47907, USA
| | - Jia Ma
- Bindley Biosciences Center, Purdue University, West Lafayette, IN, 47907, USA
| | - Daisuke Kihara
- From the Department of Biological Sciences, Purdue University, 915 W. State St., LILY G-227, West Lafayette, IN, 47907, USA
- Department of Computer Science, Purdue University, West Lafayette, IN, 47907, USA
| | - Seema Mattoo
- From the Department of Biological Sciences, Purdue University, 915 W. State St., LILY G-227, West Lafayette, IN, 47907, USA.
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Sanyal A, Chen AJ, Nakayasu ES, Lazar CS, Zbornik EA, Worby CA, Koller A, Mattoo S. A novel link between Fic (filamentation induced by cAMP)-mediated adenylylation/AMPylation and the unfolded protein response. J Biol Chem 2015; 290:8482-99. [PMID: 25601083 DOI: 10.1074/jbc.m114.618348] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The maintenance of endoplasmic reticulum (ER) homeostasis is a critical aspect of determining cell fate and requires a properly functioning unfolded protein response (UPR). We have discovered a previously unknown role of a post-translational modification termed adenylylation/AMPylation in regulating signal transduction events during UPR induction. A family of enzymes, defined by the presence of a Fic (filamentation induced by cAMP) domain, catalyzes this adenylylation reaction. The human genome encodes a single Fic protein, called HYPE (Huntingtin yeast interacting protein E), with adenylyltransferase activity but unknown physiological target(s). Here, we demonstrate that HYPE localizes to the lumen of the endoplasmic reticulum via its hydrophobic N terminus and adenylylates the ER molecular chaperone, BiP, at Ser-365 and Thr-366. BiP functions as a sentinel for protein misfolding and maintains ER homeostasis. We found that adenylylation enhances BiP's ATPase activity, which is required for refolding misfolded proteins while coping with ER stress. Accordingly, HYPE expression levels increase upon stress. Furthermore, siRNA-mediated knockdown of HYPE prevents the induction of an unfolded protein response. Thus, we identify HYPE as a new UPR regulator and provide the first functional data for Fic-mediated adenylylation in mammalian signaling.
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Affiliation(s)
| | - Andy J Chen
- From the Department of Biological Sciences and
| | - Ernesto S Nakayasu
- Bindley Biosciences Center, Purdue University, West Lafayette, Indiana 47907
| | - Cheri S Lazar
- the Department of Pharmacology, University of California at San Diego, La Jolla, California 92093, and
| | | | - Carolyn A Worby
- the Department of Pharmacology, University of California at San Diego, La Jolla, California 92093, and
| | - Antonius Koller
- the Department of Pathology, Stony Brook University, Stony Brook, New York 11794
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