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Novel structure and nucleotide binding properties of HI1480 from Haemophilus influenzae : A protein with no known sequence homologues
Author(s) -
Lim Kap,
Sarikaya Elif,
Galkin Andrey,
Krajewski Wojciech,
Pullalarevu Sadhana,
Shin JaeHo,
Kelman Zvi,
Howard Andrew,
Herzberg Osnat
Publication year - 2004
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.20148
Subject(s) - antiparallel (mathematics) , helix bundle , tetramer , dna , biology , dimer , base pair , peptide sequence , protein structure , nucleic acid sequence , palindromic sequence , stereochemistry , gene , chemistry , biochemistry , palindrome , quantum mechanics , magnetic field , crispr , enzyme , physics , organic chemistry
The crystal structure of the Haemophilus influenzae protein HI1480 was determined at 2.1‐Å resolution. The amino acid sequence of HI1480 is unique, having no homology with other known protein sequences. The protein adopts a novel α+β fold, and associates into a dimer of tightly associated dimers. The tight dimers are formed by intermolecular interactions that are mediated by an antiparallel β‐barrel involving both monomers. Helical regions of two dimers mediate the tetramer formation. The helical region contains a four‐helix bundle that has been seen only in the anticodon binding domains of class I tRNA synthetases. A cluster of four residues, Tyr18, Arg134, Glu26, and Lys12 is located in a depression formed at the four‐helix bundle/ β‐barrel interface. The arrangement is suggestive of an active center, possibly a catalytic site. The HI1480 gene is located within the Mu‐like prophage region of H. influenzae , has no homology to bacteriophage genes, and is flanked by transposases. Hence, this is an example of horizontal transfer from an unknown organism. Gel mobility shift assays revealed that HI1480 binds DNA and RNA molecules. Double‐stranded DNA is favored over single‐stranded DNA, and longer DNA molecules are bound better than shorter ones. Proteins 2004. © 2004 Wiley‐Liss, Inc.