期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 290, 期 38, 页码 23361-23370出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M115.658203
关键词
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资金
- National Institutes of Health [R01NS070899, P20GM103486]
- KSEF [KSEF-2268RDE-014, KSEF-2971-RDE-017]
- Mitzutani Foundation for Glycoscience Award
- NSF [IIA-1355438, MCB-1252345]
- ETH-Eurich
- Swiss-South African Joint Research Program [IZ LS X3122916]
- Swiss National Science Foundation SNSF [31003A_147074]
- Direct For Biological Sciences
- Div Of Molecular and Cellular Bioscience [1252345] Funding Source: National Science Foundation
- Office Of The Director
- Office of Integrative Activities [1355438] Funding Source: National Science Foundation
- Swiss National Science Foundation (SNF) [31003A_147074] Funding Source: Swiss National Science Foundation (SNF)
Glucan phosphatases are central to the regulation of starch and glycogen metabolism. Plants contain two known glucan phosphatases, Starch EXcess4 (SEX4) and Like Sex Four2 (LSF2), which dephosphorylate starch. Starch is water-insoluble and reversible phosphorylation solubilizes its outer surface allowing processive degradation. Vertebrates contain a single known glucan phosphatase, laforin, that dephosphorylates glycogen. In the absence of laforin, water-soluble glycogen becomes insoluble, leading to the neurodegenerative disorder Lafora Disease. Because of their essential role in starch and glycogen metabolism glucan phosphatases are of significant interest, yet a comparative analysis of their activities against diverse glucan substrates has not been established. We identify active site residues required for specific glucan dephosphorylation, defining a glucan phosphatase signature motif (C zeta AG Psi GR) in the active site loop. We further explore the basis for phosphate position-specific activity of these enzymes and determine that their diverse phosphate position-specific activity is governed by the phosphatase domain. In addition, we find key differences in glucan phosphatase activity toward soluble and insoluble polyglucan substrates, resulting from the participation of ancillary glucan-binding domains. Together, these data provide fundamental insights into the specific activity of glucan phosphatases against diverse polyglucan substrates.
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