1r4v

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Template:STRUCTURE 1r4v

1.9A crystal structure of protein AQ328 from Aquifex aeolicus

Overview

The structure of Aq_328, an uncharacterized protein from hyperthermophilic bacteria Aquifex aeolicus, has been determined to 1.9 A by using multi-wavelength anomalous diffraction (MAD) phasing. Although the amino acid sequence analysis shows that Aq_328 has no significant similarity to proteins with a known structure and function, the structure comparison by using the Dali server reveals that it: (1) assumes a histone-like fold, and (2) is similar to an ancestral nuclear histone protein (PDB code 1F1E) with z-score 8.1 and RMSD 3.6 A over 124 residues. A sedimentation equilibrium experiment indicates that Aq_328 is a monomer in solution, with an average sedimentation coefficient of 2.4 and an apparent molecular weight of about 20 kDa. The overall architecture of Aq_328 consists of two noncanonical histone domains in tandem repeat within a single chain, and is similar to eukaryotic heterodimer (H2A/H2B and H3/H4) and an archaeal histone heterodimer (HMfA/HMfB). The sequence comparisons between the two histone domains of Aq_328 and six eukaryotic/archaeal histones demonstrate that most of the conserved residues that underlie the Aq_328 architecture are used to build and stabilize the two cross-shaped antiparallel histone domains. The high percentage of salt bridges in the structure could be a factor in the protein's thermostability. The structural similarities to other histone-like proteins, molecular properties, and potential function of Aq_328 are discussed in this paper.

About this Structure

1R4V is a Single protein structure of sequence from Aquifex aeolicus. Full crystallographic information is available from OCA.

Reference

The crystal structure of Aq_328 from the hyperthermophilic bacteria Aquifex aeolicus shows an ancestral histone fold., Qiu Y, Tereshko V, Kim Y, Zhang R, Collart F, Yousef M, Kossiakoff A, Joachimiak A, Proteins. 2006 Jan 1;62(1):8-16. PMID:16287087 Page seeded by OCA on Sat May 3 07:04:35 2008