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Shi RL, Dillon MA, Compton PD, Sawyer WS, Thorup JR, Kwong M, Chan P, Chiu CPC, Li R, Yadav R, Lee GY, Gober JG, Li Z, ElSohly AM, Ovacik AM, Koerber JT, Spiess C, Josephs JL, Tran JC. High-Throughput Analyses of Therapeutic Antibodies Using High-Field Asymmetric Waveform Ion Mobility Spectrometry Combined with SampleStream and Intact Protein Mass Spectrometry. Anal Chem 2023; 95:17263-17272. [PMID: 37956201 DOI: 10.1021/acs.analchem.3c03158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Intact protein mass spectrometry (MS) coupled with liquid chromatography was applied to characterize the pharmacokinetics and stability profiles of therapeutic proteins. However, limitations from chromatography, including throughput and carryover, result in challenges with handling large sample numbers. Here, we combined intact protein MS with multiple front-end separations, including affinity capture, SampleStream, and high-field asymmetric waveform ion mobility spectrometry (FAIMS), to perform high-throughput and specific mass measurements of a multivalent antibody with one antigen-binding fragment (Fab) fused to an immunoglobulin G1 (IgG1) antibody. Generic affinity capture ensures the retention of both intact species 1Fab-IgG1 and the tentative degradation product IgG1. Subsequently, the analytes were directly loaded into SampleStream, where each injection occurs within ∼30 s. By separating ions prior to MS detection, FAIMS further offered improvement in signal-overnoise by ∼30% for denatured protein MS via employing compensation voltages that were optimized for different antibody species. When enhanced FAIMS transmission of 1Fab-IgG1 was employed, a qualified assay was established for spiked-in serum samples between 0.1 and 25 μg/mL, resulting in ∼10% accuracy bias and precision coefficient of variation. Selective FAIMS transmission of IgG1 as the degradation surrogate product enabled more sensitive detection of clipped species for intact 1Fab-IgG1 at 5 μg/mL in serum, generating an assay to measure 1Fab-IgG1 truncation between 2.5 and 50% with accuracy and precision below 20% bias and coefficient of variation. Our results revealed that the SampleStream-FAIMS-MS platform affords high throughput, selectivity, and sensitivity for characterizing therapeutic antibodies from complex biomatrices qualitatively and quantitatively.
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Affiliation(s)
- Rachel Liuqing Shi
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, California 94080, United States
| | - Michael A Dillon
- Department of Antibody Engineering, Genentech, Inc., South San Francisco, California 94080, United States
| | - Philip D Compton
- Integrated Protein Technologies, Evanston, Illinois 60201, United States
| | - William S Sawyer
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, California 94080, United States
| | - John R Thorup
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, California 94080, United States
| | - Mandy Kwong
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, California 94080, United States
| | - Pamela Chan
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, California 94080, United States
| | - Cecilia P C Chiu
- Department of Antibody Engineering, Genentech, Inc., South San Francisco, California 94080, United States
| | - Ran Li
- Department of Preclinical and Translational Pharmacokinetics and Pharmacodynamics, Genentech Inc., South San Francisco, California 94080, United States
| | - Rajbharan Yadav
- Department of Preclinical and Translational Pharmacokinetics and Pharmacodynamics, Genentech Inc., South San Francisco, California 94080, United States
| | - Genee Y Lee
- Department of Molecular Oncology, Genentech Inc., South San Francisco, California 94080, United States
| | - Joshua G Gober
- Department of Protein Chemistry, Genentech Inc., South San Francisco, California 94080, United States
| | - Zhiyu Li
- The DMPK Service Department, WuXi AppTec Inc., Shanghai 200131, China
| | - Adel M ElSohly
- Department of Protein Chemistry, Genentech Inc., South San Francisco, California 94080, United States
| | - Ayse Meric Ovacik
- Department of Preclinical and Translational Pharmacokinetics and Pharmacodynamics, Genentech Inc., South San Francisco, California 94080, United States
| | - James T Koerber
- Department of Antibody Engineering, Genentech, Inc., South San Francisco, California 94080, United States
| | - Christoph Spiess
- Department of Antibody Engineering, Genentech, Inc., South San Francisco, California 94080, United States
| | - Jonathan L Josephs
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, California 94080, United States
| | - John C Tran
- Department of Biochemical and Cellular Pharmacology, Genentech, Inc., South San Francisco, California 94080, United States
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2
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Chavarria-Smith J, Chiu CPC, Jackman JK, Yin J, Zhang J, Hackney JA, Lin WY, Tyagi T, Sun Y, Tao J, Dunlap D, Morton WD, Ghodge SV, Maun HR, Li H, Hernandez-Barry H, Loyet KM, Chen E, Liu J, Tam C, Yaspan BL, Cai H, Balazs M, Arron JR, Li J, Wittwer AJ, Pappu R, Austin CD, Lee WP, Lazarus RA, Sudhamsu J, Koerber JT, Yi T. Dual antibody inhibition of KLK5 and KLK7 for Netherton syndrome and atopic dermatitis. Sci Transl Med 2022; 14:eabp9159. [PMID: 36516271 DOI: 10.1126/scitranslmed.abp9159] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The epidermis is a barrier that prevents water loss while keeping harmful substances from penetrating the host. The impermeable cornified layer of the stratum corneum is maintained by balancing continuous turnover driven by epidermal basal cell proliferation, suprabasal cell differentiation, and corneal shedding. The epidermal desquamation process is tightly regulated by balance of the activities of serine proteases of the Kallikrein-related peptidases (KLK) family and their cognate inhibitor lymphoepithelial Kazal type-related inhibitor (LEKTI), which is encoded by the serine peptidase inhibitor Kazal type 5 gene. Imbalance of proteolytic activity caused by a deficiency of LEKTI leads to excessive desquamation due to increased activities of KLK5, KLK7, and KLK14 and results in Netherton syndrome (NS), a debilitating condition with an unmet clinical need. Increased activity of KLKs may also be pathological in other dermatoses such as atopic dermatitis (AD). Here, we describe the discovery of inhibitory antibodies against murine KLK5 and KLK7 that could compensate for the deficiency of LEKTI in NS. These antibodies are protective in mouse models of NS and AD and, when combined, promote improved skin barrier integrity and reduced inflammation. To translate these findings, we engineered a humanized bispecific antibody capable of potent inhibition of human KLK5 and KLK7. A crystal structure of KLK5 bound to the inhibitory Fab revealed that the antibody binds distal to its active site and uses a relatively unappreciated allosteric inhibition mechanism. Treatment with the bispecific anti-KLK5/7 antibody represents a promising therapy for clinical development in NS and other inflammatory dermatoses.
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Affiliation(s)
- Joseph Chavarria-Smith
- Department of Immunology Discovery, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Cecilia P C Chiu
- Department of Antibody Engineering, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Janet K Jackman
- Department of Immunology Discovery, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Jianping Yin
- Department of Structural Biology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Juan Zhang
- Department of Translational Immunology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Jason A Hackney
- Department of Bioinformatics, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Wei-Yu Lin
- Department of Antibody Engineering, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Tulika Tyagi
- Department of Antibody Engineering, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Yonglian Sun
- Department of Antibody Engineering, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Janet Tao
- Department of Pathology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Debra Dunlap
- Department of Pathology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - William D Morton
- Confluence Discovery Technologies Inc., 4320 Duncan Ave, Suite 400, St. Louis, MO 63108, USA
| | - Swapnil V Ghodge
- Departments of Biological Chemistry and Early Discovery Biochemistry, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Henry R Maun
- Departments of Biological Chemistry and Early Discovery Biochemistry, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Hong Li
- Department of Protein Chemistry, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Hilda Hernandez-Barry
- Department of Biochemical and Cellular Pharmacology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Kelly M Loyet
- Department of Biochemical and Cellular Pharmacology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Emily Chen
- Department of Translational Immunology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - John Liu
- Department of Translational Immunology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Christine Tam
- Department of Biomolecular Resources, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Brian L Yaspan
- Department of Human Genetics, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Hao Cai
- Department of Preclinical and Translational Pharmacokinetics, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Mercedesz Balazs
- Department of Biochemical and Cellular Pharmacology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Joseph R Arron
- Department of Immunology Discovery, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Jing Li
- Department of Biochemical and Cellular Pharmacology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Arthur J Wittwer
- Confluence Discovery Technologies Inc., 4320 Duncan Ave, Suite 400, St. Louis, MO 63108, USA
| | - Rajita Pappu
- Department of Immunology Discovery, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Cary D Austin
- Department of Pathology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Wyne P Lee
- Department of Translational Immunology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Robert A Lazarus
- Departments of Biological Chemistry and Early Discovery Biochemistry, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Jawahar Sudhamsu
- Department of Structural Biology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - James T Koerber
- Department of Antibody Engineering, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Tangsheng Yi
- Department of Immunology Discovery, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
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Jackman JK, Stockwell A, Choy DF, Xie MM, Lu P, Jia G, Li H, Abbas AR, Bronson PG, Lin WY, Chiu CPC, Maun HR, Roose-Girma M, Tam L, Zhang J, Modrusan Z, Graham RR, Behrens TW, White SR, Naureckas T, Ober C, Ferreira M, Sedlacek R, Wu J, Lee WP, Lazarus RA, Koerber JT, Arron JR, Yaspan BL, Yi T. Genome-wide association study identifies kallikrein 5 in type 2 inflammation-low asthma. J Allergy Clin Immunol 2022; 150:972-978.e7. [PMID: 35487308 DOI: 10.1016/j.jaci.2022.03.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [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: 09/30/2021] [Revised: 02/26/2022] [Accepted: 03/07/2022] [Indexed: 11/30/2022]
Abstract
BACKGROUND Clinical studies of type 2 (T2) cytokine-related neutralizing antibodies in asthma have identified a substantial subset of patients with low levels of T2 inflammation who do not benefit from T2 cytokine neutralizing antibody treatment. Non type 2 mechanisms are poorly understood in asthma but represent the redefined unmet medical need. OBJECTIVE To gain understanding of the genetic contribution to T2-low asthma. METHODS We utilized an unbiased genome-wide association study (GWAS) of moderate-severe asthma patients stratified by T2 serum biomarker periostin. We also performed additional expression and biological analysis for the top genetic hit. RESULTS This analysis identified a novel protective SNP at chr19q13.41 which is selectively associated with T2-low asthma and establishes KLK5 as the causal gene mediating this association. Heterozygous carriers of the SNP have reduced KLK5 expression. KLK5 is secreted by human bronchial epithelial cells and elevated in asthma bronchial alveolar lavage. T2 cytokines IL-4 and IL-13 downregulate KLK5 in human bronchial epithelial cells. KLK5, dependent on its catalytic function, induces epithelial chemokine/cytokine expression. Lastly, overexpression of KLK5 in airway, or lack of an endogenous KLK5 inhibitor, SPINK5, leads to spontaneous airway neutrophilic inflammation. CONCLUSION Our data identifies KLK5 as the causal gene at a novel locus at chr19q13.41 associated with T2-low asthma.
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Affiliation(s)
- Janet K Jackman
- Department of Immunology Discovery, South San Francisco, Calif
| | - Amy Stockwell
- Department of Human Genetics, South San Francisco, Calif
| | - David F Choy
- Department of Biomarker Discovery OMNI, South San Francisco, Calif
| | - Markus M Xie
- Department of Immunology Discovery, South San Francisco, Calif
| | - Peipei Lu
- Department of Immunology Discovery, South San Francisco, Calif
| | - Guiquan Jia
- Department of Biomarker Discovery OMNI, South San Francisco, Calif
| | - Hong Li
- Department of Protein Chemistry, South San Francisco, Calif
| | - Alexander R Abbas
- Department of Oncology Biomarker Development, South San Francisco, Calif
| | | | - Wei-Yu Lin
- Department of Antibody Engineering, South San Francisco, Calif
| | | | - Henry R Maun
- Department of Early Discovery Biochemistry, South San Francisco, Calif
| | | | - Lucinda Tam
- Department of Molecular Biology, South San Francisco, Calif
| | - Juan Zhang
- Department of Translational Immunology, South San Francisco, Calif
| | - Zora Modrusan
- Department of Microchemistry, Proteomics, Lipidomics and Next Generation Sequencing, Genentech Inc, South San Francisco, Calif
| | | | | | - Steven R White
- Department of Medicine, Section of Pulmonary and Critical Care, Chicago, Ill
| | - Ted Naureckas
- Department of Medicine, Section of Pulmonary and Critical Care, Chicago, Ill
| | - Carole Ober
- Department of Human Genetics, University of Chicago, Chicago, Ill
| | - Manuel Ferreira
- QIMR Berghofer Medical Research Institute, Royal Brisbane Hospital, Herston, Australia
| | - Radislav Sedlacek
- Labortory of Molecular Genetics, Institute of Molecular Genetics of the Czech Academy of Sciences, Vestec, Czech Republic
| | - Jiansheng Wu
- Department of Protein Chemistry, South San Francisco, Calif
| | - Wyne P Lee
- Department of Translational Immunology, South San Francisco, Calif
| | - Robert A Lazarus
- Department of Early Discovery Biochemistry, South San Francisco, Calif
| | - James T Koerber
- Department of Antibody Engineering, South San Francisco, Calif
| | - Joseph R Arron
- Department of Immunology Discovery, South San Francisco, Calif
| | - Brian L Yaspan
- Department of Human Genetics, South San Francisco, Calif.
| | - Tangsheng Yi
- Department of Immunology Discovery, South San Francisco, Calif.
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4
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Baruch A, Luca D, Kahn RS, Cowan KJ, Leabman M, Budha NR, Chiu CPC, Wu Y, Kirchhofer D, Peterson A, Davis JC, Tingley WG. A phase 1 study to evaluate the safety and LDL cholesterol-lowering effects of RG7652, a fully human monoclonal antibody against proprotein convertase subtilisin/kexin type 9. Clin Cardiol 2017; 40:503-511. [PMID: 28326559 DOI: 10.1002/clc.22687] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 01/20/2017] [Accepted: 01/25/2017] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Proprotein convertase subtilisin/kexin type 9 (PCSK9) downregulates low-density lipoprotein (LDL) receptors, thereby leading to a rise in circulating LDL cholesterol (LDL-C). RG7652 is a fully human monoclonal antibody against PCSK9. This placebo-controlled, phase 1 ascending-dose study in healthy subjects evaluated the safety of RG7652 and its efficacy as a potential LDL-C-lowering drug. HYPOTHESIS Anti-PCSK9 antibody therapy safely and effectively reduces LDL-C. METHODS Subjects (N = 80) were randomized into 10 cohorts. Six sequential single-dose cohorts received 10, 40, 150, 300, 600, or 800 mg of RG7652 via subcutaneous injection. Four multiple-dose cohorts received 40 or 150 mg of RG7652 once weekly for 4 weeks, either with or without statin therapy (atorvastatin). RESULTS Adverse events (AEs) were generally mild; the most common AEs were temporary injection-site reactions. No serious AEs, severe AEs, AEs leading to study-drug discontinuation, or dose-limiting toxicities were reported. RG7652 monotherapy reduced mean LDL-C levels by up to 64% and as much as 100 mg/dL at week 2; the effect magnitude and duration increased with dose (≥57 days following a single RG7652 dose ≥300 mg). Exploratory analyses showed reduced oxidized LDL, lipoprotein(a), and lipoprotein-associated phospholipase A2 with RG7652. Antidrug antibody against RG7652 tested positive in 2 of 60 (3.3%) RG7652-treated and in 4 of 20 (20.0%) placebo-treated subjects. Simultaneous atorvastatin administration did not appear to impact the pharmacokinetic profile or lipid-lowering effects of RG7652. CONCLUSIONS Overall, RG7652 elicited substantial and sustained dose-related LDL-C reductions with an acceptable safety profile and minimal immunogenicity.
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Affiliation(s)
- Amos Baruch
- Genentech Inc., South San Francisco, California
| | - Diana Luca
- Genentech Inc., South San Francisco, California
| | | | | | | | | | | | - Yan Wu
- Genentech Inc., South San Francisco, California
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5
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Lin LYC, Rakic B, Chiu CPC, Lameignere E, Wakarchuk WW, Withers SG, Strynadka NCJ. Structure and mechanism of the lipooligosaccharide sialyltransferase from Neisseria meningitidis. J Biol Chem 2011; 286:37237-48. [PMID: 21880735 DOI: 10.1074/jbc.m111.249920] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The first x-ray crystallographic structure of a CAZY family-52 glycosyltransferase, that of the membrane associated α2,3/α2,6 lipooligosaccharide sialyltransferase from Neisseria meningitidis serotype L1 (NST), has been solved to 1.95 Å resolution. The structure of NST adopts a GT-B-fold common with other glycosyltransferase (GT) families but exhibits a novel domain swap of the N-terminal 130 residues to create a functional homodimeric form not observed in any other class to date. The domain swap is mediated at the structural level by a loop-helix-loop extension between residues Leu-108 and Met-130 (we term the swapping module) and a unique lipid-binding domain. NST catalyzes the creation of α2,3- or 2,6-linked oligosaccharide products from a CMP-sialic acid (Neu5Ac) donor and galactosyl-containing acceptor sugars. Our structures of NST bound to the non-hydrolyzable substrate analog CMP-3F((axial))-Neu5Ac show that the swapping module from one monomer of NST mediates the binding of the donor sugar in a composite active site formed at the dimeric interface. Kinetic analysis of designed point mutations observed in the CMP-3F((axial))-Neu5Ac binding site suggests potential roles of a requisite general base (Asp-258) and general acid (His-280) in the NST catalytic mechanism. A long hydrophobic tunnel adjacent to the dimer interface in each of the two monomers contains electron density for two extended linear molecules that likely belong to either the two fatty acyl chains of a diglyceride lipid or the two polyethylene glycol groups of the detergent Triton X-100. In this work, Triton X-100 maintains the activity and increases the solubility of NST during purification and is critical to the formation of ordered crystals. Together, the mechanistic implications of the NST structure provide insight into lipooligosaccharide sialylation with respect to the association of substrates and the essential membrane-anchored nature of NST on the bacterial surface.
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Affiliation(s)
- Leo Y-C Lin
- Department of Biochemistry and Molecular Biology, Centre for Blood Research University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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6
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Chiu CPC, Lairson LL, Gilbert M, Wakarchuk WW, Withers SG, Strynadka NCJ. Structural Analysis of the α-2,3-Sialyltransferase Cst-I from Campylobacter jejuni in Apo and Substrate-Analogue Bound Forms,. Biochemistry 2007; 46:7196-204. [PMID: 17518445 DOI: 10.1021/bi602543d] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Sialic acid is an essential sugar in biology that plays key roles in numerous cellular processes and interactions. The biosynthesis of sialylated glycoconjugates is catalyzed by five distinct families of sialyltransferases. In the last 25 years, there has been much research on the enzymes themselves, their genes, and their reaction products, but we still do not know the precise molecular mechanism of action for this class of glycosyltransferase. We previously reported the first detailed structural and kinetic characterization of Cst-II, a bifunctional sialyltransferase (CAZy GT-42) from the bacterium Campylobacter jejuni [Chiu et al. (2004) Nat. Struct. Mol. Biol. 11, 163-170]. This enzyme can use both Gal-beta-1,3/4-R and Neu5Ac-alpha-2,3-Gal-beta-1,3/4-R as acceptor sugars. A second sialyltransferase from this bacterium, Cst-I, has been shown to utilize solely Gal-beta-1,3/4-R as the acceptor sugar in its transferase reaction. We report here the structural and kinetic characterization of this monofunctional enzyme, which belongs to the same sialyltransferase family as Cst-II, in both apo and substrate bound form. Our structural data show that Cst-I adopts a similar GTA-type glycosyltransferase fold to that of the bifunctional Cst-II, with conservation of several key noncharged catalytic residues. Significant differences are found, however, between the two enzymes in the lid domain region, which is critical to the creation of the acceptor sugar binding site. Furthermore, molecular modeling of various acceptor sugars within the active sites of these enzymes provides significant new insights into the structural basis for substrate specificities within this biologically important enzyme class.
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Affiliation(s)
- Cecilia P C Chiu
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, V6T 1Z3, Canada
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Aharoni A, Thieme K, Chiu CPC, Buchini S, Lairson LL, Chen H, Strynadka NCJ, Wakarchuk WW, Withers SG. High-throughput screening methodology for the directed evolution of glycosyltransferases. Nat Methods 2006; 3:609-14. [PMID: 16862135 DOI: 10.1038/nmeth899] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Accepted: 06/19/2006] [Indexed: 11/09/2022]
Abstract
Engineering of glycosyltransferases (GTs) with desired substrate specificity for the synthesis of new oligosaccharides holds great potential for the development of the field of glycobiology. However, engineering of GTs by directed evolution methodologies is hampered by the lack of efficient screening systems for sugar-transfer activity. We report here the development of a new fluorescence-based high-throughput screening (HTS) methodology for the directed evolution of sialyltransferases (STs). Using this methodology, we detected the formation of sialosides in intact Escherichia coli cells by selectively trapping the fluorescently labeled transfer products in the cell and analyzing and sorting the resulting cell population using a fluorescence-activated cell sorter (FACS). We screened a library of >10(6) ST mutants using this methodology and found a variant with up to 400-fold higher catalytic efficiency for transfer to a variety of fluorescently labeled acceptor sugars, including a thiosugar, yielding a metabolically stable product.
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Affiliation(s)
- Amir Aharoni
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
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8
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Lairson LL, Chiu CPC, Ly HD, He S, Wakarchuk WW, Strynadka NCJ, Withers SG. Intermediate trapping on a mutant retaining alpha-galactosyltransferase identifies an unexpected aspartate residue. J Biol Chem 2004; 279:28339-44. [PMID: 15075344 DOI: 10.1074/jbc.m400451200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lipopolysaccharyl-alpha-1,4-galactosyltransferase C (LgtC), a glycosyltransferase family 8 alpha-1,4-galactosyltransferase from Neisseria meningitidis, catalyzes the transfer of galactose from UDP galactose to terminal lactose-containing acceptor sugars with net retention of anomeric configuration. To investigate the potential role of discrete nucleophilic catalysis suggested by the double displacement mechanism generally proposed for retaining glycosyltransferases, the side chain amide of Gln-189, which is suitably positioned to act as the catalytic nucleophile of LgtC, was substituted with the more nucleophilic carboxylate-containing side chain of glutamate in the hope of accumulating a glycosyl-enzyme intermediate. The resulting mutant was subjected to kinetic, mass spectrometric, and x-ray crystallographic analysis. Although the K(m) for UDP-galactose is not significantly altered, the k(cat) was reduced to 3% that of the wild type enzyme. Electrospray mass spectrometric analysis revealed that a steady state population of the Q189E variant contains a covalently bound galactosyl moiety. Liquid chromatographic/mass spectrometric analysis of fragmented proteolytic digests identified the site of labeling not as Glu-189 but, surprisingly, as the sequentially adjacent Asp-190. However, the side chain carboxylate of Asp-190 is located 8.9 A away from the donor substrate in the available crystal structure. Kinetic analysis of a D190N mutant at this position revealed a k(cat) value 3000-fold lower than that of the wild type enzyme. A 2.6-A crystal structure of the Q189E mutant with bound uridine 5'-diphospho-2-deoxy-2-fluoro-alpha-d-galactopyranose revealed no significant perturbation of the mode of donor sugar binding nor of active site configuration. This is the first trapping of an intermediate in the active site of a retaining glycosyltransferase and, although not conclusive, implicates Asp-190 as an alternative candidate catalytic nucleophile, thereby rekindling a longstanding mechanistic debate.
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Affiliation(s)
- Luke L Lairson
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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9
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Chiu CPC, Watts AG, Lairson LL, Gilbert M, Lim D, Wakarchuk WW, Withers SG, Strynadka NCJ. Structural analysis of the sialyltransferase CstII from Campylobacter jejuni in complex with a substrate analog. Nat Struct Mol Biol 2004; 11:163-70. [PMID: 14730352 DOI: 10.1038/nsmb720] [Citation(s) in RCA: 167] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2003] [Accepted: 12/08/2003] [Indexed: 12/22/2022]
Abstract
Sialic acid terminates oligosaccharide chains on mammalian and microbial cell surfaces, playing critical roles in recognition and adherence. The enzymes that transfer the sialic acid moiety from cytidine-5'-monophospho-N-acetyl-neuraminic acid (CMP-NeuAc) to the terminal positions of these key glycoconjugates are known as sialyltransferases. Despite their important biological roles, little is understood about the mechanism or molecular structure of these membrane-associated enzymes. We report the first structure of a sialyltransferase, that of CstII from Campylobacter jejuni, a highly prevalent foodborne pathogen. Our structural, mutagenesis and kinetic data provide support for a novel mode of substrate binding and glycosyl transfer mechanism, including essential roles of a histidine (general base) and two tyrosine residues (coordination of the phosphate leaving group). This work provides a framework for understanding the activity of several sialyltransferases, from bacterial to human, and for the structure-based design of specific inhibitors.
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Affiliation(s)
- Cecilia P C Chiu
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2146 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
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