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Price JL, Culyba EK, Chen W, Murray AN, Hanson SR, Wong CH, Powers ET, Kelly JW. N-glycosylation of enhanced aromatic sequons to increase glycoprotein stability. Biopolymers 2012; 98:195-211. [PMID: 22782562 PMCID: PMC3539202 DOI: 10.1002/bip.22030] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 01/17/2012] [Accepted: 01/26/2012] [Indexed: 11/12/2022]
Abstract
N-glycosylation can increase the rate of protein folding, enhance thermodynamic stability, and slow protein unfolding; however, the molecular basis for these effects is incompletely understood. Without clear engineering guidelines, attempts to use N-glycosylation as an approach for stabilizing proteins have resulted in unpredictable energetic consequences. Here, we review the recent development of three "enhanced aromatic sequons," which appear to facilitate stabilizing native-state interactions between Phe, Asn-GlcNAc and Thr when placed in an appropriate reverse turn context. It has proven to be straightforward to engineer a stabilizing enhanced aromatic sequon into glycosylation-naïve proteins that have not evolved to optimize specific protein-carbohydrate interactions. Incorporating these enhanced aromatic sequons into appropriate reverse turn types within proteins should enhance the well-known pharmacokinetic benefits of N-glycosylation-based stabilization by lowering the population of protease-susceptible unfolded and aggregation-prone misfolded states, thereby making such proteins more useful in research and pharmaceutical applications.
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Affiliation(s)
- Joshua L. Price
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602
| | - Elizabeth K. Culyba
- Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
| | - Wentao Chen
- Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
| | - Amber N. Murray
- Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
| | - Sarah R. Hanson
- Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
| | - Chi-Huey Wong
- Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
| | - Evan T. Powers
- Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
| | - Jeffery W. Kelly
- Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037
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Price JL, Shental-Bechor D, Dhar A, Turner MJ, Powers ET, Gruebele M, Levy Y, Kelly JW. Context-dependent effects of asparagine glycosylation on Pin WW folding kinetics and thermodynamics. J Am Chem Soc 2010; 132:15359-67. [PMID: 20936810 PMCID: PMC2965790 DOI: 10.1021/ja106896t] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Asparagine glycosylation is one of the most common and important post-translational modifications of proteins in eukaryotic cells. N-glycosylation occurs when a triantennary glycan precursor is transferred en bloc to a nascent polypeptide (harboring the N-X-T/S sequon) as the peptide is cotranslationally translocated into the endoplasmic reticulum (ER). In addition to facilitating binding interactions with components of the ER proteostasis network, N-glycans can also have intrinsic effects on protein folding by directly altering the folding energy landscape. Previous work from our laboratories (Hanson et al. Proc. Natl. Acad. Sci. U.S.A. 2009, 109, 3131-3136; Shental-Bechor, D.; Levy, Y. Proc. Natl. Acad. Sci. U.S.A. 2008, 105, 8256-8261) suggested that the three sugar residues closest to the protein are sufficient for accelerating protein folding and stabilizing the resulting structure in vitro; even a monosaccharide can have a dramatic effect. The highly conserved nature of these three proximal sugars in N-glycans led us to speculate that introducing an N-glycosylation site into a protein that is not normally glycosylated would stabilize the protein and increase its folding rate in a manner that does not depend on the presence of specific stabilizing protein-saccharide interactions. Here, we test this hypothesis experimentally and computationally by incorporating an N-linked GlcNAc residue at various positions within the Pin WW domain, a small β-sheet-rich protein. The results show that an increased folding rate and enhanced thermodynamic stability are not general, context-independent consequences of N-glycosylation. Comparison between computational predictions and experimental observations suggests that generic glycan-based excluded volume effects are responsible for the destabilizing effect of glycosylation at highly structured positions. However, this reasoning does not adequately explain the observed destabilizing effect of glycosylation within flexible loops. Our data are consistent with the hypothesis that specific, evolved protein-glycan contacts must also play an important role in mediating the beneficial energetic effects on protein folding that glycosylation can confer.
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Affiliation(s)
- Joshua L. Price
- Departments of Chemistry and Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037
| | - Dalit Shental-Bechor
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel, 76100
| | - Apratim Dhar
- Center for Biophysics and Computational Biology and Departments of Chemistry and Physics, University of Illinois, Urbana, Illinois 61801
| | - Maurice J. Turner
- Departments of Chemistry and Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037
| | - Evan T. Powers
- Departments of Chemistry and Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037
| | - Martin Gruebele
- Center for Biophysics and Computational Biology and Departments of Chemistry and Physics, University of Illinois, Urbana, Illinois 61801
| | - Yaakov Levy
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel, 76100
| | - Jeffery W. Kelly
- Departments of Chemistry and Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037
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Bodian DL, Skonier JE, Bowen MA, Neubauer M, Siadak AW, Aruffo A, Bajorath J. Identification of residues in CD6 which are critical for ligand binding. Biochemistry 1997; 36:2637-41. [PMID: 9054570 DOI: 10.1021/bi962560+] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
CD6 is a member of the scavenger receptor cysteine rich protein superfamily (SRCRSF). This family includes many cell surface proteins whose three-dimensional structures and functions are presently not well understood. The extracellular region of CD6 includes 3 SRCR domains. The membrane proximal SRCR domain specifically binds the activated leukocyte cell adhesion molecule (ALCAM), a CD6 ligand belonging to the immunoglobulin superfamily. CD6-ALCAM interactions mediate immune cell adhesion and are implicated in T cell maturation and the regulation of T cell function. On the basis of SRCRSF sequence comparison, a mutagenesis analysis of the membrane proximal SRCR domain of CD6 (CD6D3) has been carried out. Fifteen mutants were characterized. Three CD6 residues were identified in a region of low sequence conservation which, when mutated, abolish ligand binding but not the binding to a panel of conformationally sensitive anti-CD6 mAbs. This study provides the first analysis of residues critical for ligand binding to a member of the SRCRSF.
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MESH Headings
- Activated-Leukocyte Cell Adhesion Molecule
- Amino Acid Sequence/genetics
- Antigens, CD/chemistry
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Antigens, Differentiation, T-Lymphocyte/chemistry
- Antigens, Differentiation, T-Lymphocyte/genetics
- Antigens, Differentiation, T-Lymphocyte/metabolism
- Binding Sites/genetics
- Cell Adhesion Molecules/metabolism
- Glycoproteins/metabolism
- Humans
- Ligands
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Protein Structure, Tertiary
- Sequence Homology, Amino Acid
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Affiliation(s)
- D L Bodian
- Bristol-Myers Squibb Pharmaceutical Research Institute, Seattle, Washington 98121, USA
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