4bwc
X-ray structure of a phospholiapse B like protein 1 from bovine kidneys
Structural highlights
FunctionPLBL1_BOVIN Phospholipase acting on various phospholipids including phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine and lysophospholipids. May have a role in the defense against invading microorganisms and in the generation of lipid mediators of inflammation (By similarity). Publication Abstract from PubMedThe main function of lysosomal proteins is to degrade cellular macromolecules. We purified a novel lysosomal protein to homogeneity from bovine kidneys. By gene annotation this protein is defined as a phospholipase B-like protein 1 (bPLBD1) and, to better understand its biological function, we solved its structure at 1.9 A resolution. We showed that bPLBD1 has uniform non-complex type N-glycosylation and that it localised to the lysosome. The first step in lysosomal protein transport, the initiation of mannose-6-phosphorylation by a N-acetylglucosamine-1-phosphotransferase, requires recognition of at least two distinct lysines on the protein surface. We identified candidate lysines by analysing the structural and sequentially conserved N-glycosylation sites and lysines in bPLBD1 and in the homologous mouse phospholipase B-like protein 2. Our model suggests that N408 is the primarily phosphorylated glycan, and K358 a key residue for N-acetylglucosamine-1-phosphotransferase recognition. Two other lysines, K334 and K342, provide the required second site for N-acetylglucosamine-1-phosphotransferase recognition. bPLBD1 is an N-terminal nucleophile (Ntn) hydrolase. By comparison with other Ntn-hydrolases, we conclude that the acyl moiety of PLBD1 substrate must be small to fit the putative binding pocket, while the space for the rest of the substrate is a large open cleft. Finally, as all the known substrates of Ntn-hydrolases have amide bonds, we suggest that bPLBD1 may be an amidase or peptidase instead of lipase, explaining the difficulty in finding a good substrate for any members of the PLBD family. (c) Proteins 2013;. (c) 2013 Wiley Periodicals, Inc. Is the Bovine lysosomal phospholipase B-like protein an amidase?,Repo H, Kuokkanen E, Oksanen E, Goldman A, Heikinheimo P Proteins. 2013 Aug 12. doi: 10.1002/prot.24388. PMID:23934913[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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