The crystal structure of the non-liganded 14-3-3σ protein: insights into determinants of isoform specific ligand binding and dimerization

Seven different, but highly conserved 14-3-3 proteins are involved in diverse signaling pathways in human cells. It isunclear how the 14-3-3σ isoform, a transcriptional target of p53, exerts its inhibitory effect on the cell cycle in thepresence of other 14-3-3 isoforms, which are constitutively expressed at high levels. In order to identify structuraldifferences between the 14-3-3 isoforms, we solved the crystal structure of the human 14-3-3σ protein at a resolutionof 2.8 ? and compared it to the known structures of 14-3-3ζ and 14-3-3τ. The global architecture of the 14-3-3σ foldis similar to the previously determined structures of 14-3-3ζ and 14-3-3τ: two 14-3-3σ molecules form a cup-shapeddimer. Significant differences between these 14-3-3 isoforms were detected adjacent to the amphipathic groove, whichmediates the binding to phosphorylated consensus motifs in 14-3-3-ligands. Another specificity determining region islocalized between amino-acids 203 to 215. These differences presumably select for the interaction with specific ligands,which may explain the different biological functions of the respective 14-3-3 isoforms. Furthermore, the two 14-3-3σmolecules forming a dimer differ by the spatial position of the ninth helix, which is shifted to the inside of the ligandinteraction surface, thus indicating adaptability of this part of the molecule. In addition, 5 non-conserved residues arelocated at the interface between two 14-3-3σ proteins forming a dimer and represent candidate determinants of homo-and hetero-dimerization specificity. The structural differences among the 14-3-3 isoforms described here presumablycontribute to isoform-specific interactions and functions.

Use of Bacterial Protein Powder in Commercial Fly Ash Pozzolana Cements for High Performance Construction Materials

Concrete, widely used construction material suffers from cracks and low tensile strength that cut down the load capacity resulting in shortening of self-life. Biologically modified construction materials become more popular for higher strength and long-term sustainability. This investigation deals with the compressive and flexural strengths increment of a novel bacterial protein (bioremediase) incorporated pozzolana cement based mortar specimens. This protein also increases durability and crack repairing attributes that is more effective in pozzolana cement. Higher constituent percentage of silicate in pozzolana cement leads to higher silica leaching activity within the matrix manifesting of higher strength and durability of the samples. Eco-friendliness and wide range temperature stability lead added advantage to the protein for potential additive in high performance concrete technology. This means in practice that a substantial part of the cement of the mortar/concrete mixtures can be left out while still obtaining needed final strength. This would substantially improve the ecological footprint (sustainability) of mortar/concrete, as it is particularly cement that causes (during its production) massive CO2 emission what negatively affects the global climate (significantly contributes to global warming).