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PDBsum entry 3vx4
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Transport protein
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PDB id
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3vx4
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References listed in PDB file
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Key reference
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Title
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Boundary of the nucleotide-Binding domain of streptococcus coma based on functional and structural analysis.
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Authors
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S.Ishii,
T.Yano,
A.Okamoto,
T.Murakawa,
H.Hayashi.
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Ref.
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Biochemistry, 2013,
52,
2545-2555.
[DOI no: ]
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PubMed id
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Abstract
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The ATP-binding cassette (ABC) transporter ComA is a key molecule essential for
the first step of the quorum-sensing system of Streptococcus. The nucleotide
binding domains (NBD) of Streptococcus mutans ComA with different N termini,
NBD1 (amino acid residues 495-760), NBD2 (517-760), and NBD3 (528-760), were
expressed, purified, and characterized. The shortest NBD3 corresponds to the
region commonly defined as NBD in the database searches of ABC transporters. A
kinetic analysis showed that the extra N-terminal region conferred a
significantly higher ATP hydrolytic activity on the NBD at a neutral pH.
Gel-filtration, X-ray crystallography, and mutational analyses suggest that at
least four to five residues beyond the N-terminal boundary of NBD3 indeed
participate in stabilizing the protein scaffold of the domain structure, thereby
facilitating the ATP-dependent dimerization of NBD which is a prerequisite to
the catalysis. These findings, together with the presence of a highly conserved
glycine residue in this region, support the redefinition of the N-terminal
boundary of the NBD of these types of ABC exporters.
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