7d74
From Proteopedia
Cryo-EM structure of GMPPA/GMPPB complex bound to GTP (state II)
Structural highlights
DiseaseGMPPA_HUMAN Triple A syndrome. The disease is caused by variants affecting the gene represented in this entry. FunctionGMPPA_HUMAN Regulatory subunit of the GMPPA-GMPPB mannose-1-phosphate guanylyltransferase complex; reduces the catalytic activity of GMPPB when part of the complex (PubMed:24035193, PubMed:33986552). Mediates allosteric feedback inhibition of GMPPB catalytic activity upon binding GDP-alpha-D-mannose (PubMed:24035193, PubMed:33986552). Together with GMPPB regulates GDP-alpha-D-mannose levels (PubMed:33986552).[1] [2] Publication Abstract from PubMedGDP-mannose (GDP-Man) is a key metabolite essential for protein glycosylation and glycophosphatidylinositol anchor synthesis, and aberrant cellular GDP-Man levels have been associated with multiple human diseases. How cells maintain homeostasis of GDP-Man is unknown. Here, we report the cryo-EM structures of human GMPPA-GMPPB complex, the protein machinery responsible for GDP-Man synthesis, in complex with GDP-Man or GTP. Unexpectedly, we find that the catalytically inactive subunit GMPPA displays a much higher affinity to GDP-Man than the active subunit GMPPB and, subsequently, inhibits the catalytic activity of GMPPB through a unique C-terminal loop of GMPPA. Importantly, disruption of the interactions between GMPPA and GMPPB or the binding of GDP-Man to GMPPA in zebrafish leads to abnormal brain development and muscle abnormality, analogous to phenotypes observed in individuals carrying GMPPA or GMPPB mutations. We conclude that GMPPA acts as a cellular sensor to maintain mannose homeostasis through allosterically regulating GMPPB. Cryo-EM structures of human GMPPA-GMPPB complex reveal how cells maintain GDP-mannose homeostasis.,Zheng L, Liu Z, Wang Y, Yang F, Wang J, Huang W, Qin J, Tian M, Cai X, Liu X, Mo X, Gao N, Jia D Nat Struct Mol Biol. 2021 May;28(5):1-12. doi: 10.1038/s41594-021-00591-9. Epub , 2021 May 13. PMID:33986552[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Homo sapiens | Large Structures | Gao N | Jia D | Liu Z | Mo X | Qing J | Wang J | Wang Y | Yang F | Zheng L | Cai X
