Left ventricular noncompaction (LVNC) and low mitochondrial membrane potential are specific for Barth syndrome.

Barth syndrome (BTHS) is an X-linked mitochondrial defect characterised by dilated cardiomyopathy, neutropaenia and 3-methylglutaconic aciduria (3-MGCA). We report on two affected brothers with c.646G > A (p.G216R) TAZ gene mutations. The pathogenicity of the mutation, as indicated by the structure-based functional analyses, was further confirmed by abnormal monolysocardiolipin/cardiolipin ratio in dry blood spots of the patients as well as the occurrence of this mutation in another reported BTHS proband. In both brothers, 2D-echocardiography revealed some features of left ventricular noncompaction (LVNC) despite marked differences in the course of the disease; the eldest child presented with isolated cardiomyopathy from late infancy, whereas the youngest showed severe lactic acidosis without 3-MGCA during the neonatal period. An examination of the patients' fibroblast cultures revealed that extremely low mitochondrial membrane potentials (mtΔΨ about 50 % of the control value) dominated other unspecific mitochondrial changes detected (respiratory chain dysfunction, abnormal ROS production and depressed antioxidant defense). 1) Our studies confirm generalised mitochondrial dysfunction in the skeletal muscle and the fibroblasts of BTHS patients, especially a severe impairment in the mtΔΨ and the inhibition of complex V activity. It can be hypothesised that impaired mtΔΨ and mitochondrial ATP synthase activity may contribute to episodes of cardiac arrhythmia that occurred unexpectedly in BTHS patients. 2) Severe lactic acidosis without 3-methylglutaconic aciduria in male neonates as well as an asymptomatic mild left ventricular noncompaction may characterise the ranges of natural history of Barth syndrome.

Alphaherpesvirinae and Gammaherpesvirinae glycoprotein L and CMV UL130 originate from chemokines.

Herpesviridae is a large family of DNA viruses divided into three subfamilies: Alpha-, Beta- and Gammaherpesvirinae. The process of herpesvirus transmission is mediated by a range of proteins, one of which is glycoprotein L (gL). Based on our analysis of the solved structures of HSV2 and EBV gH/gL complexes, we propose that Alphaherpesvirinae and Gammaherpesvirinae glycoprotein L and Betaherpesvirinae UL130 originate from chemokines. Herpes simplex virus type 2 gL and human cytomegalovirus homolog (UL130) adopt a novel C chemokine-like fold, while Epstein-Barr virus gL mimics a CC chemokine structure. Hence, it is possible that gL interface with specific chemokine receptors during the transmission of Herpesviridae. We conclude that the further understanding of the function of viral chemokine-like proteins in Herpesviridae infection may lead to development of novel prophylactic and therapeutic treatment.

Structural bioinformatics of the general transcription factor TFIID.

The Transcription Factor IID is a large macromolecular complex composed of the TATA-box binding protein (TBP) and a group of 13-14 conserved TBP-associated factors (TAFs). TAFs are known to regulate transcription at various levels - mediating transcription via interaction with activators, histone modifications; recognition and binding to promoters; acting as a platform for other Transcription Factors and RNA polymerase II. Despite numerous previous studies of the TFIID complex, the knowledge concerning the structure of its components, and thus the exact mechanism of its function, remains undetermined. To carry out an in-depth analysis of TFIID we performed the structural bioinformatic analysis of the TFIID complex. The sequence identity and similarity of 13.74% and 37.56%, respectively (calculated with PAM250 matrix) between M1 aminopeptidase protein and TAF2 and the high similarity of their putative secondary structures allowed us to model a large part of the TAF2 structure. The sequence analysis enabled the mapping of previously not fully characterized structural domains in well-studied TAF proteins (including the full histone domains of TAF4 and 12 or TAF3 and 8). In this study we provided detailed structural models for all the elements of human analyzed in the context of TFIID activity, along with indications of structural alterations within TFIID in various animal model species.

Distant homologs of anti-apoptotic factor HAX1 encode parvalbumin-like calcium binding proteins.

BACKGROUND: Apoptosis is a highly ordered and orchestrated multiphase process controlled by the numerous cellular and extra-cellular signals, which executes the programmed cell death via release of cytochrome c alterations in calcium signaling, caspase-dependent limited proteolysis and DNA fragmentation. Besides the general modifiers of apoptosis, several tissue-specific regulators of this process were identified including HAX1 (HS-1 associated protein X-1) - an anti-apoptotic factor active in myeloid cells. Although HAX1 was the subject of various experimental studies, the mechanisms of its action and a functional link connected with the regulation of apoptosis still remains highly speculative. FINDINGS: Here we provide the data which suggests that HAX1 may act as a regulator or as a sensor of calcium. On the basis of iterative similarity searches, we identified a set of distant homologs of HAX1 in insects. The applied fold recognition protocol gives us strong evidence that the distant insects' homologs of HAX1 are novel parvalbumin-like calcium binding proteins. Although the whole three EF-hands fold is not preserved in vertebrate our analysis suggests that there is an existence of a potential single EF-hand calcium binding site in HAX1. The molecular mechanism of its action remains to be identified, but the risen hypothesis easily translates into previously reported lines of various data on the HAX1 biology as well as, provides us a direct link to the regulation of apoptosis. Moreover, we also report that other family of myeloid specific apoptosis regulators - myeloid leukemia factors (MLF1, MLF2) share the homologous C-terminal domain and taxonomic distribution with HAX1. CONCLUSIONS: Performed structural and active sites analyses gave new insights into mechanisms of HAX1 and MLF families in apoptosis process and suggested possible role of HAX1 in calcium-binding, still the analyses require further experimental verification.

Functional features of gene expression profiles differentiating gastrointestinal stromal tumours according to KIT mutations and expression.

BACKGROUND: Gastrointestinal stromal tumours (GISTs) represent a heterogeneous group of tumours of mesenchymal origin characterized by gain-of-function mutations in KIT or PDGFRA of the type III receptor tyrosine kinase family. Although mutations in either receptor are thought to drive an early oncogenic event through similar pathways, two previous studies reported the mutation-specific gene expression profiles. However, their further conclusions were rather discordant. To clarify the molecular characteristics of differentially expressed genes according to GIST receptor mutations, we combined microarray-based analysis with detailed functional annotations. METHODS: Total RNA was isolated from 29 frozen gastric GISTs and processed for hybridization on GENECHIP HG-U133 Plus 2.0 microarrays (Affymetrix). KIT and PDGFRA were analyzed by sequencing, while related mRNA levels were analyzed by quantitative RT-PCR. RESULTS: Fifteen and eleven tumours possessed mutations in KIT and PDGFRA, respectively; no mutation was found in three tumours. Gene expression analysis identified no discriminative profiles associated with clinical or pathological parameters, even though expression of hundreds of genes differentiated tumour receptor mutation and expression status. Functional features of genes differentially expressed between the two groups of GISTs suggested alterations in angiogenesis and G-protein-related and calcium signalling. CONCLUSION: Our study has identified novel molecular elements likely to be involved in receptor-dependent GIST development and allowed confirmation of previously published results. These elements may be potential therapeutic targets and novel markers of KIT mutation status.

Unexpected domain composition of MACC1 links MET signaling and apoptosis.

Colorectal cancer, one of the most challenging malignancies, still has a limited number of recognized prognostic and predictive markers indicating appropriate treatment. MACC1 (metastasis-associated in colon cancer-1), a novel regulator of tumor growth and metastasis has recently been identified as an important prognostic factor of metastatic disease in colorectal cancer. The mechanism of MACC1 activity remains undetermined. Here we apply a combination of fold recognition and homology modeling algorithms to draft MACC1 function. The applied methods revealed that the MACC1 protein consists of four domains: ZU5, SH3, and two C-terminal death domains (DD). Previously a similar domain architecture (ZU5-DD) was observed in other proteins, involved mainly in signal transduction and apoptosis regulation. Based on the specific aspects of the closest homologues' biology functional hypotheses on MACC1 are proposed. A broad range of bioinformatic analyzes indicates that MACC1, besides its involvement in signal transduction from the MET receptor, links MET signaling and apoptosis.

The fold recognition of CP2 transcription factors gives new insights into the function and evolution of tumor suppressor protein p53.

The CP2 transcription factor (TFCP2) is a critical regulator of erythroid gene expression. Apart from the involvement in the transcriptional switch of globin gene promoters it activates an array of cellular and viral gene promoters. A number of homologous proteins was identified in genomes of Metazoa, with additional five homologues encoded by the human genome (TFCP2L1, UBP1, GRHL1, GRHL2, GRHL3). Although several experimental studies have already been published, the knowledge on the molecular mechanism of activity of this transcription factors remains very limited. Here we present the application of fold recognition and protein structure prediction in drafting the structure-to-function relationship of the CP2 family. The employed procedure clearly shows that the family adopts a DNA binding immunoglobulin fold homologous to the p53 (TP53) core domain, and a novel type of ubiquitin-like domain and a sterile alpha motif (SAM) form oligomerization modules. With a traceable evolution of CP2 family throughout the Metazoa group this protein family is highly likely to represent an ancestor of the critical cell cycle regulator p53. Based on this observation several functional hypotheses on structure-to-function relationship of p53 were drawn. The DNA motif recognized by p53 is a result of further specialization of the CP2 DNA-binding module. The analysis also shows the critical role of protein oligomerization for the function of this protein superfamily. Finally, the identification of distant homologs of TP53 allowed performing a phylogenetic footprinting analysis explaining the role of the specific amino acids important for both - the protein folding and the binding of DNA.