6I8X

As-p18, an extracellular fatty acid binding protein

Summary for 6I8X

• Entry DOI: 10.2210/pdb6i8x/pdb
• Descriptor: Fatty acid-binding protein homolog, VACCENIC ACID, 1,2-ETHANEDIOL, ... (5 entities in total)
• Functional Keywords: extracellular, nematodes, fatty acid binding, lipid binding protein
• Biological source: Ascaris suum (Pig roundworm)
• Total number of polymer chains: 2
• Total formula weight: 36663.41

Authors

Gabrielsen, M.,Riboldi-Tunnicliffe, A.,Ibanez-Shimabukuro, M.,Smith, B.O. (deposition date: 2018-11-21, release date: 2019-07-17, Last modification date: 2024-01-24)

Primary citation

Ibanez-Shimabukuro, M.,Rey-Burusco, M.F.,Gabrielsen, M.,Franchini, G.R.,Riboldi-Tunnicliffe, A.,Roe, A.J.,Griffiths, K.,Cooper, A.,Corsico, B.,Kennedy, M.W.,Smith, B.O.
As-p18, an extracellular fatty acid binding protein of nematodes, exhibits unusual structural features.
Biosci.Rep., 2019

PubMed Abstract: Intracellular lipid-binding proteins (iLBPs) of the fatty acid-binding protein (FABP) family of animals transport, mainly fatty acids or retinoids, are confined to the cytosol and have highly similar 3D structures. In contrast, nematodes possess fatty acid-binding proteins (nemFABPs) that are secreted into the perivitelline fluid surrounding their developing embryos. We report structures of As-p18, a nemFABP of the large intestinal roundworm , with ligand bound, determined using X-ray crystallography and nuclear magnetic resonance spectroscopy. In common with other FABPs, As-p18 comprises a ten β-strand barrel capped by two short α-helices, with the carboxylate head group of oleate tethered in the interior of the protein. However, As-p18 exhibits two distinctive longer loops amongst β-strands not previously seen in a FABP. One of these is adjacent to the presumed ligand entry portal, so it may help to target the protein for efficient loading or unloading of ligand. The second, larger loop is at the opposite end of the molecule and has no equivalent in any iLBP structure yet determined. As-p18 preferentially binds a single 18-carbon fatty acid ligand in its central cavity but in an orientation that differs from iLBPs. The unusual structural features of nemFABPs may relate to resourcing of developing embryos of nematodes.

PubMed: 31273060
DOI: 10.1042/BSR20191292

Experimental method

X-RAY DIFFRACTION (2.3 Å)