Febs Letters

doi: 10.1016/S0014-5793(14)00450-5pmid: N/A

Nick Pace, C.; Scholtz, J. Martin; Grimsley, Gerald R.

doi: 10.1016/j.febslet.2014.05.006pmid: 24846139

The goal of this article is to summarize what has been learned about the major forces stabilizing proteins since the late 1980s when site‐directed mutagenesis became possible. The following conclusions are derived from experimental studies of hydrophobic and hydrogen bonding variants. (1) Based on studies of 138 hydrophobic interaction variants in 11 proteins, burying a –CH2− group on folding contributes 1.1 ± 0.5 kcal/mol to protein stability. (2) The burial of non‐polar side chains contributes to protein stability in two ways: first, a term that depends on the removal of the side chains from water and, more importantly, the enhanced London dispersion forces that result from the tight packing in the protein interior. (3) Based on studies of 151 hydrogen bonding variants in 15 proteins, forming a hydrogen bond on folding contributes 1.1 ± 0.8 kcal/mol to protein stability. (4) The contribution of hydrogen bonds to protein stability is strongly context dependent. (5) Hydrogen bonds by side chains and peptide groups make similar contributions to protein stability. (6) Polar group burial can make a favorable contribution to protein stability even if the polar group is not hydrogen bonded. (7) Hydrophobic interactions and hydrogen bonds both make large contributions to protein stability.

Laishram, Rakesh S.

doi: 10.1016/j.febslet.2014.05.029pmid: 24873880

Almost all eukaryotic mRNAs acquire a poly(A) tail at the 3′‐end by a concerted RNA processing event: cleavage and polyadenylation. The canonical PAP, PAPα, was considered the only nuclear PAP involved in general polyadenylation of mRNAs. A phosphoinositide‐modulated nuclear PAP, Star‐PAP, was then reported to regulate a select set of mRNAs in the cell. In addition, several non‐canonical PAPs have been identified with diverse cellular functions. Further, canonical PAP itself exists in multiple isoforms thus illustrating the diversity of PAPs. In this review, we compare two nuclear PAPs, Star‐PAP and PAPα with a general overview of PAP diversity in the cell. Emerging evidence suggests distinct niches of target pre‐mRNAs for the two PAPs and that modulation of these PAPs regulates distinct cellular functions.

Shandilya, Jayasha; Senapati, Parijat; Dhanasekaran, Karthigeyan; Bangalore, Suma S.; Kumar, Manoj; Hari Kishore, A.; Bhat, Akshay; Kodaganur, Gopinath S.; Kundu, Tapas K.

doi: 10.1016/j.febslet.2014.05.014pmid: 24857377

Chen, Wan-Na; Loscha, Karin V.; Nitsche, Christoph; Graham, Bim; Otting, Gottfried

doi: 10.1016/j.febslet.2014.05.018pmid: 24859037

The C‐terminal β‐hairpin of NS2B (NS2Bc) in the dengue virus NS2B–NS3 protease is required for full enzymatic activity. In crystal structures without inhibitor and in the complex with bovine pancreatic trypsin inhibitor (BPTI), NS2Bc is displaced from the active site. In contrast, nuclear magnetic resonance (NMR) studies in solution only ever showed NS2Bc in the enzymatically active closed conformation. Here we demonstrate by pseudocontact shifts from a lanthanide tag that NS2Bc remains in the closed conformation also in the complex with BPTI. Therefore, the closed conformation is the best template for drug discovery.

Raghunathan, Kannan; Harris, Paul T.; Spurbeck, Rachel R.; Arvidson, Cindy G.; Arvidson, Dennis N.

doi: 10.1016/j.febslet.2014.05.020pmid: 24859038

Enolases are highly conserved metalloenzymes ubiquitous to cellular metabolism. While these enzymes share a large degree of sequence and structural similarity, they have been shown to possess a wide range of moonlighting functions. Recent studies showed that an enolase from Lactobacillus gasseri impedes the ability of Neisseria gonorrhoeae to adhere to epithelial cells. We present the crystal structure of this enolase, the first from Lactobacillus, with one of its Mg2+ cofactors. Determined using molecular replacement to 2.08 Å, the structure has a flexible and surface exposed catalytic loop containing lysines, and may play a role in the inhibitory function.

Milochau, Alexandra; Lagrée, Valérie; Benassy, Marie-Noëlle; Chaignepain, Stéphane; Papin, Julien; Garcia-Arcos, Itsaso; Lajoix, Anne; Monterrat, Carole; Coudert, Laetitia; Schmitter, Jean-Marie; Ochoa, Begoña; Lang, Jochen

Lanyon-Hogg, Thomas; Hooper, Jacob; Gunn, Sarah; Warriner, Stuart L.; Baker, Alison

doi: 10.1016/j.febslet.2014.05.038pmid: 24879895

PEX5 acts as a cycling receptor for import of PTS1 proteins into peroxisomes and as a co‐receptor for PEX7, the PTS2 receptor, but the mechanism of cargo unloading has remained obscure. Using recombinant protein domains we show PEX5 binding to the PEX14N‐terminal domain (PEX14N) has no effect on the affinity of PEX5 for a PTS1 containing peptide. PEX5 can form a complex containing both recombinant PTS1 cargo and endogenous PEX7‐thiolase simultaneously but isolation of the complex via the PEX14 construct resulted in an absence of thiolase, suggesting a possible role for PEX14 in the unloading of PTS2 cargos.

Hagenmueller, Marco; Riffel, Johannes H.; Bernhold, Elmar; Fan, Jingjing; Katus, Hugo A.; Hardt, Stefan E.

doi: 10.1016/j.febslet.2014.05.039pmid: 24879894

The Wnt signaling pathway was identified as crucial mediator of cardiomyocyte hypertrophy. In this study we found that activation of non‐canonical Wnt signaling by Wnt5a stimulates protein synthesis and enlargement of cardiomyocyte surface area. These hypertrophic features were inhibited in Dapper‐1 (Dpr1) depleted cells. On the molecular level, we observed inhibition of the non‐canonical Wnt/planar‐cell‐polarity (PCP) pathway denoted by reduction of c‐jun‐n‐terminal‐kinase (JNK) phosphorylation. Upstream of JNK, increased protein levels of the Wnt/PCP trans‐membrane receptor van‐Gogh‐like‐2 (Vangl2) were observed along with an enrichment of Vangl2 in perinuclear located vesicles. The findings suggest that Dpr1 is essential for execution of the Wnt/PCP pathway and regulation of the Vangl2/JNK axis. Depletion of Dpr1 inhibits non‐canonical Wnt signaling induced cardiomyocyte hypertrophy by blocking Wnt/PCP signaling.

Xia, Yang; Wu, Yanhu; Liu, Bin; Wang, Pengli; Chen, Yijiang

doi: 10.1016/j.febslet.2014.05.002pmid: 24842609

Aberrant expression of microRNAs has been shown to regulate the biological processes of lung cancer cells. However, the role of miR‐638 in the development of NSCLC is still unclear. In this study, low miR‐638 and high SOX2 were shown to be associated with tumor size and metastasis of NSCLC patients. Downregulated miR‐638 could promote cell invasion and proliferation, while high miR‐638 expression reversed the effect. Furthermore, miR‐638 could regulate SOX2 by directly binding to its 3′‐UTR. Silencing of SOX2 by siRNA partially abolished the enhancement of cell invasion and proliferation induced by downregulated miR‐638. Aberrant miR‐638 expression could modulate the expression levels of markers of epithelial‐to‐mesenchymal transition. Our results indicate that miR‐638 may play a pivotal role in the development of NSCLC.