Febs Letters

doi: 10.1016/S0014-5793(05)00810-0pmid: N/A

doi: 10.1016/S0014-5793(05)00840-9pmid: N/A

Walma, Tine

doi: 10.1016/j.febslet.2005.06.032pmid: N/A

Silles, Eduardo; Osorio, Hugo; Maia, Rita; Günther Sillero, María A.; Sillero, Antonio

doi: 10.1016/j.febslet.2005.06.017pmid: 16023109

Low concentrations of HgCl2 elicited, in Saccharomyces cerevisiae, a transitory increase in the ATP level followed by a decrease of its concentration, until almost disappearance. At 1 μM HgCl2, the increase in ATP lasted for about 30 min, while at 10 μM the increase was only observed in the first 5 min of treatment. The initial burst of ATP was accompanied by a decrease in the level of hexose phosphates, whereas during the decrease of ATP an increase in the inosine and hexose phosphates levels took place. The treatment with HgCl2 inhibited the plasma membrane proton ATPase but not the activities of hexokinase or 6‐phosphofructokinase.

Langer, Thomas; Sreeramulu, Sridhar; Vogtherr, Martin; Elshorst, Bettina; Betz, Marco; Schieborr, Ulrich; Saxena, Krishna; Schwalbe, Harald

doi: 10.1016/j.febslet.2005.06.015pmid: 16026785

The catalytic subunit of cAMP‐dependent protein kinase (PKA) can easily be expressed in Escherichia coli and is catalytically active. Four phosphorylation sites are known in PKA (S10, S139, T197 and S338), and the isolated recombinant protein is a mixture of different phosphorylated forms. Obtaining uniformly phosphorylated protein requires separation of the protein preparation leading to significant loss in protein yield. It is found that the mutant S10A/S139D/S338D has similar properties as the wild‐type protein, whereas additional replacement of T197 with either E or D reduces protein expression yield as well as folding propensity of the protein. Due to its high sequence homology to Akt/PKB, which cannot easily be expressed in E. coli, PKA has been used as a surrogate kinase for drug design. Several mutations within the ATP binding site have been described to make PKA even more similar to Akt/PKB. Two proteins with Akt/PKB‐like mutations in the ATP binding site were made (PKAB6 and PKAB8), and in addition S10, S139 and S338 phosphorylation sites have been removed. These proteins can be expressed in high yields but have reduced activity compared to the wild‐type. Proper folding of all proteins was analyzed by 2D 1H, 15N‐TROSY NMR experiments.

Byun, Hee Sun; Cho, Eun Wie; Kim, Jin Sik; Moon, Myung Sook; Yum, Jung Joo; Kim, Kug Chan; Kim, In Gyu

doi: 10.1016/j.febslet.2005.06.023pmid: 16024017

An increment of thioredoxin‐1 (TRX) is observed in many human primary cancers and appears to contribute to an increase of cell growth and a resistance to chemotherapy. On the contrary, when TRX was overexpressed in the HT‐1080 fibrosarcoma cells, the cell growth was retarded and chromosomal polyploidy and cellular senescence were induced. TRX‐overexpression made HT‐1080 cells resistant to an oxidative stress caused by H2O2 or paraquat. But these cells were significantly sensitive to ionizing radiation, showing an abrogation of the G2 checkpoint. Their DNA contents were twice of the controls and they expressed typical senescence markers. Their expression levels of p53 and cyclin‐dependent kinase inhibitors (CDKI) were about 2–3‐fold higher than the control. Nevertheless, cyclin D1 and D3, which are negatively regulated by CDKIs, were also increased. Overall, in HT‐1080 cells the TRX‐overexpression created a state of cellular senescence caused by a simultaneous stimulation of the mitogen‐activated pathways and an inhibition of the cyclin‐dependent kinases, which is known as a hypermitogenic arrest.

Rosaleny, Lorena E.; Antúnez, Oreto; Ruiz-García, Ana B.; Pérez-Ortín, José E.; Tordera, Vicente

doi: 10.1016/j.febslet.2005.06.028pmid: 16023114

HAT‐B is a yeast histone acetyltransferase composed of Hat1, Hat2 and Hif1 proteins. We demonstrate that a hat2 mutant or a hat1hat2 double mutant, but not a hat1 mutant, have an extended life‐span. Transcriptome analysis shows that the single hat mutants are not very different from wild type. However, the comparison of the hat1 and hat2 transcriptomes shows that they are different. The hat1hat2 double mutant shows a transcriptional phenotype similar to that of the hat1 mutant but strongly enhanced. These results indicate that Hat2p could have additional functions in the cell to those of Hat1p.

Teraishi, Fuminori; Kagawa, Shunsuke; Watanabe, Takanori; Tango, Yasuhisa; Kawashima, Takeshi; Umeoka, Tatsuo; Nisizaki, Masahiko; Tanaka, Noriaki; Fujiwara, Toshiyoshi

doi: 10.1016/j.febslet.2005.06.031pmid: 16023108

Cariou, Bertrand; van Harmelen, Kirsten; Duran-Sandoval, Daniel; van Dijk, Theo; Grefhorst, Aldo; Bouchaert, Emmanuel; Fruchart, Jean-Charles; Gonzalez, Frank J.; Kuipers, Folkert; Staels, Bart

doi: 10.1016/j.febslet.2005.06.033pmid: 16023103

Xue, Bin; Wu, Yifan; Yin, Zhimin; Zhang, Hong; Sun, Suwen; Yi, Tangsheng; Luo, Lan

doi: 10.1016/j.febslet.2005.06.034pmid: 16023107

Glutathione S‐transferase P1(GSTP1) plays an important role in the detoxification and xenobiotics metabolism. Here, we show that GSTP1 is also involved in LPS (lipopolysaccharide)‐induced inflammatory response. GSTP1 expression, determined at the transcription and translation levels, were upregulated by the LPS stimulation in RAW264.7 macrophage‐like cells. GSTP1 inhibited LPS‐induced mitogen‐activated protein kinases MAPKs including ERK, JNK and p38 as well as NF‐κB activation dose‐ and time‐dependently in transient transfected and stable transfected cells. Moreover this inhibition of the signaling pathways resulted in the decrease of tumor necrosis factor alpha (TNF‐α) and nitric oxide (NO) synthesis. These data suggest that the GSTP1 prevents LPS‐induced excessive production of pro‐inflammatory factors and plays an anti‐inflammatory role in response to LPS.