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PDBsum entry 2dch
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References listed in PDB file
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Key reference
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Title
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Structure of a hyperthermophilic archaeal homing endonuclease, I-Tsp061i: contribution of cross-Domain polar networks to thermostability.
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Authors
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H.Nakayama,
T.Shimamura,
T.Imagawa,
N.Shirai,
T.Itoh,
Y.Sako,
M.Miyano,
H.Sakuraba,
T.Ohshima,
N.Nomura,
H.Tsuge.
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Ref.
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J Mol Biol, 2007,
365,
362-378.
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PubMed id
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Note: In the PDB file this reference is
annotated as "TO BE PUBLISHED". The citation details given above have
been manually determined.
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Abstract
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A novel LAGLIDADG-type homing endonuclease (HEase), I-Tsp061I, from the
hyperthermophilic archaeon Thermoproteus sp. IC-061 16 S rRNA gene (rDNA) intron
was characterized with respect to its structure, catalytic properties and
thermostability. It was found that I-Tsp061I is a HEase isoschizomer of the
previously described I-PogI and exhibits the highest thermostability among the
known LAGLIDADG-type HEases. Determination of the crystal structure of I-Tsp061I
at 2.1 A resolution using the multiple isomorphous replacement and anomalous
scattering method revealed that the overall fold is similar to that of other
known LAGLIDADG-type HEases, despite little sequence similarity between
I-Tsp061I and those HEases. However, I-Tsp061I contains important cross-domain
polar networks, unlike its mesophilic counterparts. Notably, the polar network
Tyr6-Asp104-His180-107O-HOH12-104O-Asn177 exists across the two packed
alpha-helices containing both the LAGLIDADG catalytic motif and the GxxxG
hydrophobic helix bundle motif. Another important structural feature is the
salt-bridge network Asp29-Arg31-Glu182 across N and C-terminal domain interface,
which appears to contribute to the stability of the domain/domain packing. On
the basis of these structural analyses and extensive mutational studies, we
conclude that such cross-domain polar networks play key roles in stabilizing the
catalytic center and domain packing, and underlie the hyperthermostability of
I-Tsp061I.
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