The traditional computational modeling of protein structure, dynamics, and interactions remains difficult for many protein systems. It is mostly due to the size of protein conformational spaces and required simulation time scales that are still too large to be studied in atomistic detail. Lowering the level of protein representation from all-atom to coarse-grained opens up new possibilities for studying protein systems. In this review we provide an overview of coarse-grained models focusing on their design, including choices of representation, models of energy functions, sampling of conformational space, and applications in the modeling of protein structure, dynamics, and interactions. A more detailed description is given for applications of coarse-grained models suitable for efficient combinations with all-atom simulations in multiscale modeling strategies.

Protein-peptide interactions play essential functional roles in living organisms and their structural characterization is a hot subject of current experimental and theoretical research. Computational modeling of the structure of protein-peptide interactions is usually divided into two stages: prediction of the binding site at a protein receptor surface, and then docking (and modeling) the peptide structure into the known binding site. This paper presents a comprehensive CABS-dock method for the simultaneous search of binding sites and flexible protein-peptide docking, available as a user's friendly web server. We present example CABS-dock results obtained in the default CABS-dock mode and using its advanced options that enable the user to increase the range of flexibility for chosen receptor fragments or to exclude user-selected binding modes from docking search. Furthermore, we demonstrate a strategy to improve CABS-dock performance by assessing the quality of models with classical molecular dynamics. Finally, we discuss the promising extensions and applications of the CABS-dock method and provide a tutorial appendix for the convenient analysis and visualization of CABS-dock results. The CABS-dock web server is freely available at http://biocomp.chem.uw.edu.pl/CABSdock/.

The clinical presentation of asthma results from complex gene-gene and gene-environment interactions. The natural variability of the DNA sequence within the NR3C1 gene affects the activity of glucocorticoid receptors (GCRs). The NR3C1 gene is localized on chromosome 5q31–q32. The gene coding for the GCR comprises nine exons. The structural domains of the GCR determine the biological functions of the functional domains. The observed resistance to glucocorticosteroids and the normal metabolic profile of Tth111I single nucleotide polymorphism (SNP) carriers is due to the ER22/23EK polymorphism that is present in them. BclI polymorphism significantly affects the process of alternative NR3C1 gene splicing and within that mechanism increases the sensitivity to glucocorticoids (GCs). A total of 451 subjects were enrolled in the present study, including 235 qualified to the group of bronchial asthma patients. A group of 216 healthy participants with no history of asthma or atopic conditions was qualified for the study. Genotyping was accomplished using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and PCR-high resolution melting (HRM) methods. No statistically significant differences were observed in the frequency of Tth111I, BclI and ER22/23EK polymorphisms of the NR3C1 gene when comparing mild, moderate and severe asthma vs. the control group. Investigative analyses demonstrated statistically significant correlations for alleles and genotypes of Tth111I polymorphism of the NR3C1 gene between healthy subjects and patients with severe asthma characterized by a control profile corresponding to an Asthma Control Test (ACT)™ score ≥20. It was established that only the Tth111I polymorphism of the NR3C1 gene plays an important role in the pathogenesis of chronic bronchitis leading to the development of asthma with both allergic and non-allergic etiology.

BiP is the only Hsp70 chaperone in the endoplasmic reticulum (ER) and similar to other Hsp70s, its activity relies on nucleotide- and substrate-controllable docking and undocking of its nucleotide-binding domain (NBD) and substrate-binding domain (SBD). However, little is known of specific features of the BiP conformational landscape that tune BiP to its unique tasks and the ER environment. We present methyl NMR analysis of the BiP chaperone cycle that reveals surprising conformational heterogeneity of ATP-bound BiP that distinguishes BiP from its bacterial homologue DnaK. This unusual poise enables gradual post-translational regulation of the BiP chaperone cycle and its chaperone activity by subtle local perturbations at SBD allosteric ‘hotspots’. In particular, BiP inactivation by AMPylation of its SBD does not disturb Hsp70 inter-domain allostery and preserves BiP structure. Instead it relies on a redistribution of the BiP conformational ensemble and stabilization the domain-docked conformation in presence of ADP and ATP.

Transforming growth factor-β1 (TGF-β1) is an important fibrogenic and immunomodulatory cytokine participating in the pathogenesis of a number of illnesses related to the growth, differentiation and migration of cells. It also plays a key role in inflammation, atherosclerosis, vascular inflammation and asthma. The aim of the present study was to evaluate the association between the expression of the TGF-β1 gene and its genetic polymorphisms, and the disease phenotype. The study comprised 173 patients with asthma, as well as 163 healthy volunteers as a control group. The gender profiles of the groups were similar (p=0.8415). Genotyping was performed by polymerase chain reaction (PCR)-high resolution melting (HRM). The results were verified by sequencing. Gene expression was evaluated by RT-PCR. This study evaluated the role and frequency of genetic polymorphisms (C−509T, C+466T and T+869C) of the TGF-β1 gene in the study group (patients with asthma) and the control group (healthy volunteers). The results obtained for the patients and healthy controls were as follows: C−509T single nucleotide polymorphism (SNP) (controls, TT/CT/CC-0.4444/0.5309/0.0247; patients, TT/CT/CC-0.3699/0.6012/0.0289), C+466T SNP (controls, TT/CT/CC-1.000/0.000/0.000; patients, TT/CT/CC-1.000/0.000/0.000) and T+869C SNP (controls, TT/CT/CC-1.000/0.000/0.000; patients, TT/CT/CC-1.000/0.000/0.000). Only the C−509T polymorphism was found to play a significant role in the pathogenesis of asthma, as well as a risk factor in the loss of the clinical control of the disease [TT vs. CC/CT, odds ratio (OR) 2.38; confidence interval (CI) 1.22–4.66; p=0.0103]. A significant difference was noted between the study and control groups with regard to the mRNA expression of TGF-β1 (p=0.0133). A higher level of expression of the TGF-β1 gene correlated with the time of diagnosis of patients over 16 years of age (p=0.0255). This study demonstrates that the C−509T SNP is a significant clinical risk factor for asthma and that the TGF-β1 cytokine contributes to the progression of the illness.

Glucocorticosteroids (GCs) are basic drugs in therapy of a number of diseases, including chronic diseases of the respiratory system. They are the most important anti-inflammatory drugs in the treatment of asthma. GCs after binding to the glucocorticoid receptor (GR) form the complex (transcription factor), which acts on promoter and regulatory parts of genes enhancing the expression of anti-inflammatory proteins and decreasing the proinflammatory protein synthesis, including numerous cytokines mediating inflammation in the course of asthma. Non-sensitivity or resistance to GCs favours an increase in the TGF-β expression. This cytokine plays a central role in asthma inducing fibroblast differentiation and extracellular matrix synthesis. TGF-β isoforms, 1, 2 and 3, are located on chromosome 19q13, 1q41 and 14q24, respectively. GCs reduce TGF-β 1 and TGF-β 2 production and significantly decrease the expression of upregulated TGF-β 1 and TGF-β 2 mRNA induced by exogenous TGF-β. In asthma, TGF-β may play a role in the development of the peribronchiolar and subepithelial fibrosis, which contributes to a significant clinical exacerbation of asthma. Therefore, it is possible that NR3C1 glucocorticoid receptor gene polymorphisms could exert varied effects on the TGF-β mRNA expression and fibrotic process in lungs of asthmatic patients. The aim of the study was to evaluate the impact of polymorphic forms (Tth111I, BclI, ER22/23EK, N363S) of the NR3C1 gene on the level of the TGF-β 1 mRNA expression. A total of 173 patients with asthma and 163 healthy volunteers participated in the study. Genotyping of Tth111I, BclI, ER22/23EK, and N363S polymorphisms of the NR3C1 gene was performed by using PCR-HRM and PCR-RFLP techniques. TGF-β mRNA was assessed by real time RT-PCR. Tth111I SNP significantly (p = 0.0115) correlated with the TGF-β 1 mRNA expression level. The significance of AA and GG genotypes of Tth111I SNP in increasing and decreasing the level of the TGF-β 1 mRNA expression was demonstrated. Both BclI SNP and ER22/23EK SNP did not affect the expression level of the cytokine analysed. The N363S SNP AA genotype of NR3C1 gene statistically significantly influenced the increase in the level of the TGF-β 1 mRNA expression. Thus, SNPs of NR3C1 gene play an important regulatory function in the bronchi of patients suffering from asthma. In the case of the occurrence of Tth111I and N363S polymorphic forms of the gene studied, a reduced ability of GCs to inhibit the TGF-β 1 expression can be observed.

Vibrio cholerae, the marine bacterium responsible for the diarrheal disease cholera, utilizes a multitude of virulence factors to cause disease. The importance of two of these factors, the toxin co-regulated pilus (TCP) and cholera toxin (CT), has been well documented for pandemic O1 and epidemic O139 serogroups. In contrast, endemic non-O1 and non-O139 serogroups can cause localized outbreaks of cholera-like illness, often in the absence of TCP and CT. One virulence mechanism used by these strains is the type VI secretion system (T6SS) to export toxins across the cell envelope and confer toxicity toward eukaryotic and prokaryotic organisms. The V. cholerae strain V52 (an O37 serogroup strain) possesses a constitutively active T6SS and was responsible for an outbreak of gastroenteritis in Sudan in 1968. To evaluate a potential role of the T6SS in the disease cholera, we compared the T6SS clusters of V. cholerae strains with sequenced genomes. We found that the majority of V. cholerae strains, including one pandemic strain, contain intact T6SS gene clusters; thus, we propose that the T6SS is a conserved mechanism that allows pandemic and endemic V. cholerae to persist both in the host and in the environment.

The aim of the present study was to identify polymorphic forms of the nuclear receptor subfamily 3, group C, member 1 (NR3C1) and transforming growth factor β1 (TGF-β1) genes and evaluate their impact on the expression levels of interleukin (IL)-5 and IL‑15 in asthma. The study was conducted on a control group consisting of 91 people (54 women and 37 men). The patient group consisted of 130 participants (86 women and 44 men). Genotyping was performed by polymerase chain reaction‑restriction fragment length polymorphism (PCR‑RFLP) and PCR‑high resolution melting (HRM) methods. Interleukin expression was measured by reverse transcription‑quantitative polymerase chain reaction. The frequency of the polymorphic forms in the analyzed group were observed to be: Tth111I (rs10052957) controls AA 0.0440, AG 0.5714, GG 0.3846, patients AA 0.1538/AG 0.4692, GG 0.3769; ER22/23EK (rs6189 /rs6190) controls AG 0.0556, GG 0.9444, patients AG 0.0385, GG 0.9615; N363S (rs6195) controls AA 0.6444, AG 0.2667, GG 0.0889, patients AA 0.7846, AG 0.1385, GG 0.0769; BclI (rs41423247) controls CC 0.0879, CG 0.5604, GG 0.3516, patients CC 0.1008, CG 0.5736, GG 0.3256; C‑509T (rs1800469) controls TT 0.0805, CT 0.6322, CC 0.2874, patients TT 0.1102, CT 0.5669, CC 0.3228. The results indicated that the C‑509T single nucleotide polymorphism (SNP) of the TGF-β1 gene contributed to an increase in the IL‑5 mRNA expression levels. The GG genotype of the N363S SNP of the NR3C1 gene was observed to result in an increase in the expression levels of IL‑15. The present study indicated that the selected SNPs of the NR3C1 and TGF‑β1 genes demonstrate a regulatory effect on the expression of IL‑5 and IL‑15. Therefore, genetic variation affects inflammation in asthma and the clinical course of the disease.