Dataset Information

Crystal structure of zebrafish complement 1qA globular domain.

ABSTRACT: C1q contains three globular domains (C1qgD) that are the key functional component of the classical complement system. C1qgD can interact with important immune molecules, including IgG and C-reactive protein (CRP) to form defense systems to protect animals. Here, the first non-mammalian structure, zebrafish C1qA globular domain (Dare-C1qAgD) was solved. Although the overall architecture of Dare-C1qAgD is similar to human C1qA, residues involved in C1qBgD, C1qCgD, and CRP binding are somewhat different while residues involved in IgG binding are not present in zebrafish. The structure gives insight into how human and fish C1qA evolved from an ancestral protein.

SUBMITTER: Yuan H

PROVIDER: S-EPMC5029524 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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Crystal structure of zebrafish complement 1qA globular domain.

Yuan Hongyu H Chen Rong R Tariq Mansoor M Liu Yanjie Y Sun Yaping Y Xia Chun C

Protein science : a publication of the Protein Society 20160913 10

C1q contains three globular domains (C1qgD) that are the key functional component of the classical complement system. C1qgD can interact with important immune molecules, including IgG and C-reactive protein (CRP) to form defense systems to protect animals. Here, the first non-mammalian structure, zebrafish C1qA globular domain (Dare-C1qAgD) was solved. Although the overall architecture of Dare-C1qAgD is similar to human C1qA, residues involved in C1qBgD, C1qCgD, and CRP binding are somewhat diff ...[more]

PMID: 27391278

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Project description:BACKGROUND:Protein N-glycosylation occurs in the three domains of life. Oligosaccharyltransferase (OST) transfers an oligosaccharide chain to the asparagine residue in the N-glycosylation sequons. The catalytic subunits of the OST enzyme are STT3 in eukaryotes, AglB in archaea and PglB in eubacteria. The genome of a hyperthermophilic archaeon, Archaeoglobus fulgidus, encodes three paralogous AglB proteins. We previously solved the crystal structures of the C-terminal globular domains of two paralogs, AglB-Short 1 and AglB-Short 2. RESULTS:We determined the crystal structure of the C-terminal globular domain of the third AglB paralog, AglB-Long, at 1.9 Å resolutions. The crystallization of the fusion protein with maltose binding protein (MBP) afforded high quality protein crystals. Two MBP-AglB-L molecules formed a swapped dimer in the crystal. Since the fusion protein behaved as a monomer upon gel filtration, we reconstituted the monomer structure from the swapped dimer by exchanging the swapped segments. The C-terminal domain of A. fulgidus AglB-L includes a structural unit common to AglB-S1 and AglB-S2. This structural unit contains the evolutionally conserved WWDYG and DK motifs. The present structure revealed that A. fulgidus AglB-L contained a variant type of the DK motif with a short insertion, and confirmed that the second signature residue, Lys, of the DK motif participates in the formation of a pocket that binds to the serine and threonine residues at the +2 position of the N-glycosylation sequon. CONCLUSIONS:The structure of A. fulgidus AglB-L, together with the two previously solved structures of AglB-S1 and AglB-S2, provides a complete overview of the three AglB paralogs encoded in the A. fulgidus genome. All three AglBs contain a variant type of the DK motif. This finding supports a previously proposed rule: The STT3/AglB/PglB paralogs in one organism always contain the same type of Ser/Thr-binding pocket. The present structure will be useful as a search model for molecular replacement in the structural determination of the full-length A. fulgidus AglB-L.

Dataset Information

Crystal structure of zebrafish complement 1qA globular domain.

Publications

Crystal structure of zebrafish complement 1qA globular domain.

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