Dataset Information

Metal-binding loop length and not sequence dictates structure.

ABSTRACT: The C-terminal copper-binding loop in the beta-barrel fold of the cupredoxin azurin has been replaced with a range of sequences containing alanine, glycine, and valine residues to assess the importance of amino acid composition and the length of this region. The introduction of 2 and 4 alanines between the coordinating Cys, His, and Met results in loop structures matching those in naturally occurring proteins with the same loop lengths. A loop with 4 alanines between the Cys and His and 3 between the His and Met ligands has a structure identical to that of the WT protein, whose loop is the same length. Loop structure is dictated by length and not sequence allowing the properties of the main surface patch for interactions with partners, to which the loop is a major contributor, to be optimized. Loops with 2 amino acids between the ligands using glycine, alanine, and valine residues have been compared. An empirical relationship is found between copper site protection by the loop and reduction potential. A loop adorned with 4 methyl groups is sufficient to protect the copper ion, enabling most sequences to adequately perform this task. The mutant with 3 alanine residues between the ligands forms a strand-swapped dimer in the crystal structure, an arrangement that has not, to our knowledge, been seen previously for this family of proteins. Cupredoxins function as redox shuttles and are required to be monomeric; therefore, none have evolved with a metal-binding loop of this length.

SUBMITTER: Sato K

PROVIDER: S-EPMC2666997 | biostudies-literature | 2009 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Metal-binding loop length and not sequence dictates structure.

Sato Katsuko K Li Chan C Salard Isabelle I Thompson Andrew J AJ Banfield Mark J MJ Dennison Christopher C

Proceedings of the National Academy of Sciences of the United States of America 20090319 14

The C-terminal copper-binding loop in the beta-barrel fold of the cupredoxin azurin has been replaced with a range of sequences containing alanine, glycine, and valine residues to assess the importance of amino acid composition and the length of this region. The introduction of 2 and 4 alanines between the coordinating Cys, His, and Met results in loop structures matching those in naturally occurring proteins with the same loop lengths. A loop with 4 alanines between the Cys and His and 3 betwee ...[more]

PMID: 19299503

Similar Datasets

Project description:MotivationMetal binding proteins have a central role in maintaining life processes. Nearly one-third of known protein structures contain metal ions that are used for a variety of needs, such as catalysis, DNA/RNA binding, protein structure stability, etc. Identifying metal binding proteins is thus crucial for understanding the mechanisms of cellular activity. However, experimental annotation of protein metal binding potential is severely lacking, while computational techniques are often imprecise and of limited applicability.ResultsWe developed a novel machine learning-based method, mebipred, for identifying metal binding proteins from sequence-derived features. This method is over 80% accurate in recognizing proteins that bind metal ion-containing ligands; the specific identity of eleven ubiquitously-present metal ions can also be annotated. mebipred is reference-free, i.e. no sequence alignments are involved, and is thus faster than alignment-based methods; it also more accurate than other sequence-based prediction methods. Additionally, mebipred can identify protein metal binding capabilities from short sequence stretches, e.g. translated sequencing reads, and, thus, may be useful for the annotation of metal requirements of metagenomic samples. We performed an analysis of available microbiome data and found that ocean, hot spring sediments, and soil microbiomes use a more diverse set of metals than human host-related ones. For human microbiomes, physiological conditions explain the observed metal preferences. Similarly, subtle changes in ocean sample ion concentration affect the abundance of relevant metal binding proteins. These results highlight mebipred's utility in analysing microbiome metal requirements.Availabilitymebipred is available as a web server at services.bromberglab.org/mebipred and as a standalone package at https://pypi.org/project/mymetal/.Supplementary informationSupplementary data are available from Bioinformatics online repository. Additional data is available from http://dx.doi.org/10.5281/zenodo.5722730 and http://dx.doi.org/10.5281/zenodo.6332940.

Project description:Two mechanisms, induced fit (IF) and conformational selection (CS), have been proposed to explain ligand recognition coupled conformational changes. The histidine binding protein (HisJ) adopts the CS mechanism, in which a pre-equilibrium is established between the open and the closed states with the ligand binding to the closed state. Despite being structurally similar to HisJ, the maltose binding protein (MBP) adopts the IF mechanism, in which the ligand binds the open state and induces a transition to the closed state. To understand the molecular determinants of this difference, we performed molecular dynamics (MD) simulations of coarse-grained dual structure based models. We find that intra-protein contacts unique to the closed state are sufficient to promote the conformational transition in HisJ, indicating a CS-like mechanism. In contrast, additional ligand-mimicking contacts are required to "induce" the conformational transition in MBP suggesting an IF-like mechanism. In agreement with experiments, destabilizing modifications to two structural features, the spine helix (SH) and the balancing interface (BI), present in MBP but absent in HisJ, reduce the need for ligand-mimicking contacts indicating that SH and BI act as structural restraints that keep MBP in the open state. We introduce an SH like element into HisJ and observe that this can impede the conformational transition increasing the importance of ligand-mimicking contacts. Similarly, simultaneous mutations to BI and SH in MBP reduce the barrier to conformational transitions significantly and promote a CS-like mechanism. Together, our results show that structural restraints present in the protein structure can determine the mechanism of conformational transitions and even simple models that correctly capture such structural features can predict their positions. MD simulations of such models can thus be used, in conjunction with mutational experiments, to regulate protein ligand interactions, and modulate ligand binding affinities.

Dataset Information

Metal-binding loop length and not sequence dictates structure.

Publications

Metal-binding loop length and not sequence dictates structure.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets