From Proteopedia
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The FpgNei Protein Superfamily
Functional Units
| G. Stereothermophilus Fpg
| E. Coli Nei
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| Functional Cluster | Variant 1 | Variant 2 | Fpg1 | Fpg2 | Plant | Neil1 | Neil2 | Neil3 | Proteo | Actino1 | Actino2 | MimiVirus
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| Support for perfectly conserved Asn168
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| Y | Y | N | N | N | N | N | N | N | N
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| Stability of catalytic helix
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| Y | Y | Y | N | N | N | N | N | N | N
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Functional Cluster 1: Stability of perfectly conserved Asn168
Asn168, along with two other amino acids have an effect in the orientation and kinking of the DNA. In 4 of the 9 clades (Fpg1, Fpg2 and Plants and Fungi) Asn168 is supported by Lys160, which in turn hydrogen bonds with Leu249 and Ser250. In the other clades (Actinobacteria 1 and 2, Proteacteria and all vertebrate sequences), Arg171 that comes from a different helix fulfills the same roles as Lys160. One important difference is that the Zinc Finger is shaped differently in the absence of DNA, and there is a hydrogen bond between one of the ?-sheets and the arginine. One hypothesis is that the arginine or the lysine is necessary to support the Asn168, crucial for orientation of the DNA.
Evolution
References