1mrd
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PREPARATION, CHARACTERIZATION AND CRYSTALLIZATION OF AN ANTIBODY FAB FRAGMENT THAT RECOGNIZES RNA. CRYSTAL STRUCTURES OF NATIVE FAB AND THREE FAB-MONONUCLEOTIDE COMPLEXES
OverviewOverview
Fab fragments from Jel 103, an antibody which specifically binds to, single-stranded poly(rl), were prepared by papain digestion, separated, into eight isoforms and characterized by mass spectrometry. One of the, purified isoforms yielded crystals suitable for structural studies by, X-ray diffraction and its crystal structure was determined to 2.4 A, resolution. Soaking the crystals in solutions containing either of the, mononucleotides inosine-5'-diphosphate, guanosine-5'-diphosphate or, deoxyinosine-5'-monophosphate resulted in binding of the nucleotide in a, single binding site. However, adenosine-5'-diphosphate does not bind to, this antibody. The recognition of the base is achieved through hydrogen, bonds to the C6 carbonyl oxygen and the imino NH group of the purine in a, pattern similar to that of the base-base interactions in a double-stranded, nucleic acid. Additional binding energy is provided by stacking of the, base and the Tyr32L side-chain and by interaction of the alpha-phosphate, with the antibody in an anionic binding site. Most of the side-chains, interacting with the nucleotide come from the light chain. Surprisingly, this antibody shares the VL sequence with another nucleic acid-binding, antibody, BV04-1. The latter binds to a single stranded DNA with a high, preference for thymine bases. The structures of the unliganded and, complexed Jel 103 Fab are compared to those of BV-04-1 Fab and while they, show similarity in recognition of the base of the immunodominant, nucleotide, their 5' phosphates occupy different positions, suggesting, different orientation of the nucleic acid bound to these two antibodies., Differences in the conformations of the L1 loops between the two Fabs have, been noted.
About this StructureAbout this Structure
1MRD is a Protein complex structure of sequences from [1] with ZN, IMD and IDP as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Preparation, characterization and crystallization of an antibody Fab fragment that recognizes RNA. Crystal structures of native Fab and three Fab-mononucleotide complexes., Pokkuluri PR, Bouthillier F, Li Y, Kuderova A, Lee J, Cygler M, J Mol Biol. 1994 Oct 21;243(2):283-97. PMID:7523684
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