Persistent directional cell migration requires ion transport proteins as direction sensors and membrane potential differences in order to maintain directedness

Background  

Ion transport proteins generate small electric fields that can induce directional cell motility; however, little is known about their mechanisms that lead to directedness. We investigated Na, K-ATPase (NaKA) and Na+/H+ exchanger isoforms (NHE1 and 3) in SaOS-2 and Calvarial osteoblasts, which present anode- and cathode- directed motility, during electrotaxis.     

Cover Image,Volume 116, Number 3, March 2019

Transglutaminase (TGase) induces the cross-linking of proteins by catalyzing an acyl transfer reaction. TGase is a zymogen, activated by the removal of its pro-region. Because the pro-region is crucial for folding and inhibition of the TGase activity, the recombinant expression of the mature TGase (mTGase) without the pro-region, usually results in inactive inclusion bodies or low protein yield. Here, Streptomyces netropsis TGase was fused with Escherichia coli lysyl-tRNA synthetase (LysRS), as a module with chaperoning activity in an RNA dependent manner (chaperna). The TGase activity from purified fusion protein induced via the removal of LysRS by tev protease in vitro. Moreover, active mTGase was produced in E. coli via an intracellular cleavage system, wherein LysRS-mTGase was cleaved by the coexpressed tev protease in vivo. The results suggest that LysRS essentially mimics pro-region, which exerts a dual function—folding of TGase into active conformation and keeping it as dormant state—in an RNA-dependent manner. Thus, trans-acting RNAs, prompt the cis-acting chaperone function of LysRS, while being mechanistically similar to the intramolecular chaperone function of the pro-region. These results could be implemented and extended for the folding of “difficult-to-express” recombinant proteins, by harnessing the chaperna function.     

Effects of poly-gamma-glutamic acid on inflammatory and metabolic biomarkers in sleep-restricted rats

Sleep and Biological Rhythms - To evaluate the effects of poly-gamma-glutamic acid (γ-PGA) administration on inflammatory and metabolic biomarkers in sleep-restricted rats, we conducted an...     

Phenotypic and epigenetic adaptation of the moss clone to mercury

One/third of microregenerants derived from the clone of a single cell of the Pottia intermedia gametophyte survived and formed protonemal mats on a surface of the Knop agar with 0.5 μM HgCl₂. A high survival rate (in percents) argues for the epigenetic character of adaptation. Epigenetic adaptation of the clone is accompanied by increasing of a cell number in leaves, by increasing of the peroxidase activity and by the intensification of the activity zone of the peroxidase isoform, a molecular weight of which was 66 kDa, and by the appearance of two isoforms of this enzyme on the electrophoregram. The significantly weak increasing of the peroxidase activity was manifested in the regenerants from the Pottia clone, which demonstrated an adaptation to 0.2 μM HgCl₂ on a mass scale [8]; the epigenetically adapted regenerants grown in a metal free media were different from the physiologically adapted regenerants only by the intensification of the zone of activity of the isoform with a molecular weight of 66 kDa. This could be the reason to consider the epigenetic adaptation to the elevated mercury concentration as an intensified epigenecopy of the modification and to point out to the similarity of the mechanisms of both types of adaptation.