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Nutho B, Pengthaisong S, Tankrathok A, Lee VS, Ketudat Cairns JR, Rungrotmongkol T, Hannongbua S. Structural Basis of Specific Glucoimidazole and Mannoimidazole Binding by Os3BGlu7. Biomolecules 2020; 10:biom10060907. [PMID: 32549280 PMCID: PMC7356692 DOI: 10.3390/biom10060907] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 06/09/2020] [Accepted: 06/11/2020] [Indexed: 01/07/2023] Open
Abstract
β-Glucosidases and β-mannosidases hydrolyze substrates that differ only in the epimer of the nonreducing terminal sugar moiety, but most such enzymes show a strong preference for one activity or the other. Rice Os3BGlu7 and Os7BGlu26 β-glycosidases show a less strong preference, but Os3BGlu7 and Os7BGlu26 prefer glucosides and mannosides, respectively. Previous studies of crystal structures with glucoimidazole (GIm) and mannoimidazole (MIm) complexes and metadynamic simulations suggested that Os7BGlu26 hydrolyzes mannosides via the B2,5 transition state (TS) conformation preferred for mannosides and glucosides via their preferred 4H3/4E TS conformation. However, MIm is weakly bound by both enzymes. In the present study, we found that MIm was not bound in the active site of crystallized Os3BGlu7, but GIm was tightly bound in the -1 subsite in a 4H3/4E conformation via hydrogen bonds with the surrounding residues. One-microsecond molecular dynamics simulations showed that GIm was stably bound in the Os3BGlu7 active site and the glycone-binding site with little distortion. In contrast, MIm initialized in the B2,5 conformation rapidly relaxed to a E3/4H3 conformation and moved out into a position in the entrance of the active site, where it bound more stably despite making fewer interactions. The lack of MIm binding in the glycone site in protein crystals and simulations implies that the energy required to distort MIm to the B2,5 conformation for optimal active site residue interactions is sufficient to offset the energy of those interactions in Os3BGlu7. This balance between distortion and binding energy may also provide a rationale for glucosidase versus mannosidase specificity in plant β-glycosidases.
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Affiliation(s)
- Bodee Nutho
- Center of Excellence in Computational Chemistry (CECC), Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand;
| | - Salila Pengthaisong
- School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (S.P.); (A.T.)
- Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - Anupong Tankrathok
- School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (S.P.); (A.T.)
- Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - Vannajan Sanghiran Lee
- Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia;
| | - James R. Ketudat Cairns
- School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; (S.P.); (A.T.)
- Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
- Correspondence: (J.R.K.C.); (T.R.); (S.H.); Tel.: +66-4422-4304 (J.R.K.C.); +66-2218-5426 (T.R.); +66-2218-7602 (S.H.)
| | - Thanyada Rungrotmongkol
- Biocatalyst and Environmental Biotechnology Research Unit, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
- Program in Bioinformatics and Computational Biology, Graduate School, Chulalongkorn University, Bangkok 10330, Thailand
- Correspondence: (J.R.K.C.); (T.R.); (S.H.); Tel.: +66-4422-4304 (J.R.K.C.); +66-2218-5426 (T.R.); +66-2218-7602 (S.H.)
| | - Supot Hannongbua
- Center of Excellence in Computational Chemistry (CECC), Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand;
- Correspondence: (J.R.K.C.); (T.R.); (S.H.); Tel.: +66-4422-4304 (J.R.K.C.); +66-2218-5426 (T.R.); +66-2218-7602 (S.H.)
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van Haren MJ, Marechal N, Troffer-Charlier N, Cianciulli A, Sbardella G, Cavarelli J, Martin NI. Transition state mimics are valuable mechanistic probes for structural studies with the arginine methyltransferase CARM1. Proc Natl Acad Sci U S A 2017; 114:3625-30. [PMID: 28330993 DOI: 10.1073/pnas.1618401114] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Coactivator associated arginine methyltransferase 1 (CARM1) is a member of the protein arginine methyltransferase (PRMT) family and methylates a range of proteins in eukaryotic cells. Overexpression of CARM1 is implicated in a number of cancers, and it is therefore seen as a potential therapeutic target. Peptide sequences derived from the well-defined CARM1 substrate poly(A)-binding protein 1 (PABP1) were covalently linked to an adenosine moiety as in the AdoMet cofactor to generate transition state mimics. These constructs were found to be potent CARM1 inhibitors and also formed stable complexes with the enzyme. High-resolution crystal structures of CARM1 in complex with these compounds confirm a mode of binding that is indeed reflective of the transition state at the CARM1 active site. Given the transient nature of PRMT-substrate complexes, such transition state mimics represent valuable chemical tools for structural studies aimed at deciphering the regulation of arginine methylation mediated by the family of arginine methyltransferases.
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