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NMR structure of HI0004, a putative essential gene product from Haemophilus influenzae , and comparison with the X‐ray structure of an Aquifex aeolicus homolog
Author(s) -
Yeh Deok Cheon,
Parsons Lisa M.,
Parsons James F.,
Liu Fang,
Eisenstein Edward,
Orban John
Publication year - 2005
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.041096705
Subject(s) - aquifex aeolicus , antiparallel (mathematics) , structural genomics , heteronuclear molecule , sequence alignment , peptide sequence , conserved sequence , crystallography , homology modeling , protein structure , homology (biology) , haemophilus influenzae , biology , nuclear magnetic resonance spectroscopy , sequence (biology) , protein secondary structure , gene , genetics , computational biology , chemistry , stereochemistry , biochemistry , bacteria , escherichia coli , physics , enzyme , quantum mechanics , magnetic field
The solution structure of the 154‐residue conserved hypothetical protein HI0004 has been determined using multidimensional heteronuclear NMR spectroscopy. HI0004 has sequence homologs in many organisms ranging from bacteria to humans and is believed to be essential in Haemophilus influenzae , although an exact function has yet to be defined. It has a α–β–α sandwich architecture consisting of a central four‐stranded β‐sheet with the α2‐helix packed against one side of the β‐sheet and four α‐helices (α1, α3, α4, α5) on the other side. There is structural homology with the eukaryotic matrix metalloproteases (MMPs), but little sequence similarity except for a conserved region containing three histidines that appears in both the MMPs and throughout the HI0004 family of proteins. The solution structure of HI0004 is compared with the X‐ray structure of an Aquifex aeolicus homolog, AQ_1354, which has 36% sequence identity over 148 residues. Despite this level of sequence homology, significant differences exist between the two structures. These differences are described along with possible functional implications of the structures.