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PDBsum entry 2f1e
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Structural genomics, unknown function
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PDB id
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2f1e
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References listed in PDB file
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Key reference
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Title
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Solution structure of apag from xanthomonas axonopodis pv. Citri reveals a fibronectin-3 fold.
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Authors
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D.O.Cicero,
G.M.Contessa,
T.A.Pertinhez,
M.Gallo,
A.M.Katsuyama,
M.Paci,
C.S.Farah,
A.Spisni.
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Ref.
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Proteins, 2007,
67,
490-500.
[DOI no: ]
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PubMed id
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Abstract
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ApaG proteins are found in a wide variety of bacterial genomes but their
function is as yet unknown. Some eukaryotic proteins involved in protein-protein
interactions, such as the human polymerase delta-interacting protein (PDIP38)
and the F Box A (FBA) proteins, contain ApaG homology domains. We have used NMR
to determine the solution structure of ApaG protein from the plant pathogen
Xanthomonas axonopodis pv. citri (ApaG(Xac)) with the aim to shed some light on
its molecular function. ApaG(Xac) is characterized by seven antiparallel beta
strands forming two beta sheets, one containing three strands (ABE) and the
other four strands (GFCC'). Relaxation measurements indicate that the protein
has a quite rigid structure. In spite of the presence of a putative GXGXXG
pyrophosphate binding motif ApaG(Xac) does not bind ATP or GTP, in vitro. On the
other hand, ApaG(Xac) adopts a fibronectin type III (Fn3) fold, which is
consistent with the hypothesis that it is involved in mediating protein-protein
interactions. The fact that the proteins of ApaG family do not display
significant sequence similarity with the Fn3 domains found in other eukaryotic
or bacterial proteins suggests that Fn3 domain may have arisen earlier in
evolution than previously estimated.
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Figure 2.
Figure 2. Structure of ApaG[Xac]. (A) and (B) Topological
representation of ApaG[Xac] (C) Stereo view of an overlay of the
backbone atoms of 20 superimposed structures. (D) Ribbon
representation of the structure.
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Figure 5.
Figure 5. (A) Comparison of the 3D structure of ApaG[Xac]
(left) and NCAM F3 Module 2 (1LWR, right). The topology of
ApaG[Xac] is identical to that of FN3 modules, but with
significantly longer strands B, C  ,
and E (depicted in red). (B) Superimposition of ApaG[Xac]
(green) and (O-glycosyl)  galactosidase
(1BGL, red).
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The above figures are
reprinted
by permission from John Wiley & Sons, Inc.:
Proteins
(2007,
67,
490-500)
copyright 2007.
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