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Chen A, Mindrebo JT, Davis TD, Kim WE, Katsuyama Y, Jiang Z, Ohnishi Y, Noel JP, Burkart MD. Mechanism-based cross-linking probes capture the Escherichia coli ketosynthase FabB in conformationally distinct catalytic states. Acta Crystallogr D Struct Biol 2022; 78:1171-1179. [PMID: 36048156 PMCID: PMC9435599 DOI: 10.1107/s2059798322007434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 07/20/2022] [Indexed: 11/10/2022] Open
Abstract
Ketosynthases (KSs) catalyse essential carbon-carbon bond-forming reactions in fatty-acid biosynthesis using a two-step, ping-pong reaction mechanism. In Escherichia coli, there are two homodimeric elongating KSs, FabB and FabF, which possess overlapping substrate selectivity. However, FabB is essential for the biosynthesis of the unsaturated fatty acids (UFAs) required for cell survival in the absence of exogenous UFAs. Additionally, FabB has reduced activity towards substrates longer than 12 C atoms, whereas FabF efficiently catalyses the elongation of saturated C14 and unsaturated C16:1 acyl-acyl carrier protein (ACP) complexes. In this study, two cross-linked crystal structures of FabB in complex with ACPs functionalized with long-chain fatty-acid cross-linking probes that approximate catalytic steps were solved. Both homodimeric structures possess asymmetric substrate-binding pockets suggestive of cooperative relationships between the two FabB monomers when engaged with C14 and C16 acyl chains. In addition, these structures capture an unusual rotamer of the active-site gating residue, Phe392, which is potentially representative of the catalytic state prior to substrate release. These structures demonstrate the utility of mechanism-based cross-linking methods to capture and elucidate conformational transitions accompanying KS-mediated catalysis at near-atomic resolution.
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Affiliation(s)
- Aochiu Chen
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Jeffrey T. Mindrebo
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
- Jack H. Skirball Center for Chemical Biology and Proteomics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Tony D. Davis
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Woojoo E. Kim
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Yohei Katsuyama
- Department of Biotechnology, The Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Ziran Jiang
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Yasuo Ohnishi
- Department of Biotechnology, The Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Joseph P. Noel
- Jack H. Skirball Center for Chemical Biology and Proteomics, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Michael D. Burkart
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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Lin X, Tsao CT, Kyomoto M, Zhang M. Injectable Natural Polymer Hydrogels for Treatment of Knee Osteoarthritis. Adv Healthc Mater 2022; 11:e2101479. [PMID: 34535978 DOI: 10.1002/adhm.202101479] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/29/2021] [Indexed: 12/11/2022]
Abstract
Osteoarthritis (OA) is a serious chronic and degenerative disease that increasingly occurs in the aged population. Its current clinical treatments are limited to symptom relief and cannot regenerate cartilage. Although a better understanding of OA pathophysiology has been facilitating the development of novel therapeutic regimen, delivery of therapeutics to target sites with minimal invasiveness, high retention, and minimal side effects remains a challenge. Biocompatible hydrogels have been recognized to be highly promising for controlled delivery and release of therapeutics and biologics for tissue repair. In this review, the current approaches and the challenges in OA treatment, and unique properties of injectable natural polymer hydrogels as delivery system to overcome the challenges are presented. The common methods for fabrication of injectable polysaccharide-based hydrogels and the effects of their composition and properties on the OA treatment are detailed. The strategies of the use of hydrogels for loading and release cargos are also covered. Finally, recent efforts on the development of injectable polysaccharide-based hydrogels for OA treatment are highlighted, and their current limitations are discussed.
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Affiliation(s)
- Xiaojie Lin
- Department of Materials Science and Engineering University of Washington Seattle WA 98195 USA
| | - Ching Ting Tsao
- Department of Materials Science and Engineering University of Washington Seattle WA 98195 USA
| | - Masayuki Kyomoto
- Medical R&D Center Corporate R&D Group KYOCERA Corporation 800 Ichimiyake, Yasu Shiga 520‐2362 Japan
| | - Miqin Zhang
- Department of Materials Science and Engineering University of Washington Seattle WA 98195 USA
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