Analysis of the Nse3/MAGE-binding domain of the Nse4/EID family proteins

Background

The Nse1, Nse3 and Nse4 proteins form a tight sub-complex of the large SMC5-6 protein complex. hNSE3/MAGEG1, the mammalian ortholog of Nse3, is the founding member of the MAGE (melanoma-associated antigen) protein family and the Nse4 kleisin subunit is related to the EID (E1A-like inhibitor of differentiation) family of proteins. We have recently shown that human MAGE proteins can interact with NSE4/EID proteins through their characteristic conserved hydrophobic pocket.

Methodology/Principal Findings

Using mutagenesis and protein-protein interaction analyses, we have identified a new Nse3/MAGE-binding domain (NMBD) of the Nse4/EID proteins. This short domain is located next to the Nse4 N-terminal kleisin motif and is conserved in all NSE4/EID proteins. The central amino acid residues of the human NSE4b/EID3 domain were essential for its binding to hNSE3/MAGEG1 in yeast two-hybrid assays suggesting they form the core of the binding domain. PEPSCAN ELISA measurements of the MAGEC2 binding affinity to EID2 mutant peptides showed that similar core residues contribute to the EID2-MAGEC2 interaction. In addition, the N-terminal extension of the EID2 binding domain took part in the EID2-MAGEC2 interaction. Finally, docking and molecular dynamic simulations enabled us to generate a structure model for EID2-MAGEC2. Combination of our experimental data and the structure modeling showed how the core helical region of the NSE4/EID domain binds into the conserved pocket characteristic of the MAGE protein family.

Conclusions/Significance

We have identified a new Nse4/EID conserved domain and characterized its binding to Nse3/MAGE proteins. The conservation and binding of the interacting surfaces suggest tight co-evolution of both Nse4/EID and Nse3/MAGE protein families.

Interactions between the Nse3 and Nse4 components of the SMC5-6 complex identify evolutionarily conserved interactions between MAGE and EID Families

BACKGROUND

The SMC5-6 protein complex is involved in the cellular response to DNA damage. It is composed of 6-8 polypeptides, of which Nse1, Nse3 and Nse4 form a tight sub-complex. MAGEG1, the mammalian ortholog of Nse3, is the founding member of the MAGE (melanoma-associated antigen) protein family and Nse4 is related to the EID (E1A-like inhibitor of differentiation) family of transcriptional repressors.

METHODOLOGY/PRINCIPAL FINDINGS

Using site-directed mutagenesis, protein-protein interaction analyses and molecular modelling, we have identified a conserved hydrophobic surface on the C-terminal domain of Nse3 that interacts with Nse4 and identified residues in its N-terminal domain that are essential for interaction with Nse1. We show that these interactions are conserved in the human orthologs. Furthermore, interaction of MAGEG1, the mammalian ortholog of Nse3, with NSE4b, one of the mammalian orthologs of Nse4, results in transcriptional co-activation of the nuclear receptor, steroidogenic factor 1 (SF1). In an examination of the evolutionary conservation of the Nse3-Nse4 interactions, we find that several MAGE proteins can interact with at least one of the NSE4/EID proteins.

CONCLUSIONS/SIGNIFICANCE

We have found that, despite the evolutionary diversification of the MAGE family, the characteristic hydrophobic surface shared by all MAGE proteins from yeast to humans mediates its binding to NSE4/EID proteins. Our work provides new insights into the interactions, evolution and functions of the enigmatic MAGE proteins.

[Symptomatic approach to musculoskeletal dysfunction and chronic pelvic and perineal pain]

INTRODUCTION

Clinical examination of a patient with chronic pelvic and perineal pain often demonstrates muscle hypertonia or muscle contracture sometimes associated with local tenderness or real muscle trigger points. It is sometimes very difficult to determine whether this muscle pain detected on clinical examination is the cause or a consequence of the pain. The purpose of this article is to review musculoskeletal dysfunction in the context of chronic pelvic and perineal pain.

MATERIAL AND METHODS

Review of the literature devoted to musculoskeletal aspects of pelvic and perineal pain.

RESULTS

Definitions of pelvic floor dysfunction, hyperactive pelvic floor, myofascial pain and muscle trigger points, and the concept of fibromyalgia.

CONCLUSION

Musculoskeletal pain is certainly underestimated in the management of chronic pelvic and perineal pain. The pathophysiology of musculoskeletal pain involves disorders of the lumbar, pelvic and femoral equilibrium, myofascial pain characterized by the presence of trigger points for which the pathophysiology remains controversial: a purely muscle disease, reaction to adjacent inflammatory reactions causing hypersensitization, or simply a sign of central hypersensitization in a context of chronic pain syndrome.

Le neurochirurgien face aux algies périnéales

The investigation of patients suffering from perineal pain when sitting led us to perform an anatomical study of the pudendal nerve. We dissected 50 cadavers and found areas of conflict for the nerve fibers. The nerve trunk can become entrapped at the level of the ischiatic spine, in the Alcock's canal and when it crosses the falciform process. Considering the clinical and neurophysiological data, this type of chronic pain may arise from compression of the nerve between the sacro-tuberal and the sacro-spinal ligaments, and/or in the fascia of the internal obturator muscle. Much like treatment of entrapment of the median nerve in the wrist, we decided to treat chronic perineal pain by nerve blocks, and later by surgery. We describe here the clinical symptoms, the neurophysiological data, and the technique of the nerve blocks. For patients with persistent pain, we propose a posterior surgical approach which has provided successful pain relief in two third of patients.

Regulation of the expression of amy TO1 encoding a thermostable alpha-amylase from Streptomyces sp. TO1, in its original host and in Streptomyces lividans TK24

In its original host, the thermophilic Streptomyces strain sp. TO1, the amy TO1 gene was expressed during growth but only in the presence of starch in the growth medium. When cloned in Streptomyces lividans, on a low copy number replicative plasmid, amy TO1 expression was detectable in fructose-, mannitol- and galactose-grown cultures but not in glucose- or glycerol-grown cultures. This basal expression could be further induced by maltotriose. In a mutant strain of S. lividans disrupted for the LacI-like negative transcriptional regulator (NTR) Reg1, and when the symmetry of the dyadic symmetry element located in the promoter region of amy TO1 was altered, the basal levels of amy TO1 expression were significantly higher than those of the wild-type strain, and the maltotriose inducibility was abolished. These results suggest that, in S. lividans, amy TO1 expression is under the control of the NTR Reg1 due to its interaction with the dyadic symmetry element.

Isolation and identification of Bacillus sphaericus strains pathogenic for mosquito larvae

Three selective media for the isolation of Bacillus sphaericus have been compared. BATS medium and a formulation employing adenosine as the principal carbon source were the most effective for the recovery of spores of strain 1593. Anthranilic acid as the principal carbon source was less efficient. Eighty-four strains were isolated from mud samples using these media and were identified by computer. Identifications were confirmed for representative strains using DNA sequence homology. Most were B. sphaericus sensu stricto or members of an unnamed group. However, one strain (BSE 18) was identified as the DNA homology group IIB and this organism was found to be highly toxic toward larvae of Culex pipiens. Southern hybridization of BSE 18 DNA to a probe prepared from the cloned toxin gene from strain 1593 revealed that BSE 18 contained a typical gene for the 41.9-kDa toxin.

The promoter of the beta-glucosidase gene from Kluyveromyces fragilis contains sequences that act as upstream repressing sequences in Saccharomyces cerevisiae

The relationship between the promoter length of the Kluyveromyces fragilis beta-glucosidase gene and the level of its expression in Saccharomyces cerevisiae was studied by gene fusion between deleted promoter fragments of various lengths and the promoterless beta-galactosidase gene of Escherichia coli. The removal of a region from position -425 to -232 led to a tenfold increase in the expression of the gene. The same results were obtained for the reconstructed beta-glucosidase gene with the same promoter length. It is likely that the deletion of this part of the promoter removes negative regulatory elements which are functional in Saccharomyces cerevisiae. This increase in activity is the main event which may explain the high increase in gene expression (60-fold) previously observed for an upstream deletion obtained during subcloning experiments of the beta-glucosidase gene. It is also shown that the expression of the gene greatly depends upon the nature of the recipient strain, the growth phase of the cell and that of the vector carrying it.

Sequence and transcription of the beta-glucosidase gene of Kluyveromyces fragilis cloned in Saccharomyces cerevisiae

The complete nucleotide sequence of the beta-glucosidase gene of Kluyveromyces fragilis has been determined. This sequence contains an open reading frame of 2535 base pairs encoding a protein of 845 amino acids. Analysis of the transcription products revealed only one transcript of about 3 kb identical in both Kluyveromyces fragilis and in the expression host Saccharomyces cerevisiae. The protein molecular weight of 93,811 Kd deduced from the sequence is consistent with the 90,000 Kd determined by SDS polyacrylamide gel electrophoresis with the purified protein. Mapping of the starts of transcription shows that two starting points are used in the natural host Kluyveromyces fragilis. A comparison of the amino acid sequence with that of other beta-glucosidases revealed three regions of homology. One of these regions contains an amino acid sequence very similar to a peptide isolated from the active site of beta-glucosidase A3 from Aspergillus wentii and could be implicated in the catalytic mechanism of these glucolytic enzymes.

Cloning and expression of the structural gene for beta-glucosidase of Kluyveromyces fragilis in Escherichia coli and Saccharomyces cerevisiae

Cellobiose, the last product in cellulose degradation, is converted into two molecules of glucose by a beta-glucosidase. S. cerevisiae does posses the structural gene for a beta-glucosidase, but it is very poorly expressed; we thus decided to isolate and characterize that of Kluyveromyces fragilis. We constructed in E. coli HB101 strain a genomic library of the Kluyveromyces fragilis Y610 strain (ATCC 12424), a yeast able to grow on cellobiose and which constitutively produces the beta-glucosidase. The structural gene for beta-glucosidase was identified by its expression in E. coli. The initial isolated cosmid KF1 contained an insert of 35 Kb and by successive subcloning the insert size was reduced to 3.5 Kb (KF4). This cloned beta-glucosidase gene introduced in S. cerevisiae by transformation is expressed at a level of about 500 times that of K. fragilis. We checked by Southern hybridization that the high expression level was not due to a rearrangement of K. fragilis DNA during the cloning experiments. Nevertheless to obtain yeast transformants able to grow on cellobiose a yeast strain whose permeability to sugar is increased must be used and this last point is discussed.

Mitochondrial and nuclear mutagenicity of ellipticine and derivatives in the yeast Saccharomyces cerevisiae

Haploid strains of the yeast Saccharomyces cerevisiae were tested for their sensitivity to ellipticine and nine derivatives; some of them exhibiting antitumor properties. Different mutagenic properties of ellipticines are described. Charged ellipticines, which were ineffective in Ames' bacterial assay, were found to be potent inducers of the mitochondrial p- mutation: induction proceeded even in the absence of growth. Uncharged ellipticines increased mitochondrial antibiotic resistance mutations, whereas charged derivatives decreased them. Ellipticine derivatives enhanced, reduced, or did not change the reversion frequencies of nuclear auxotrophic markers. The result depended on the strain being tested: no structure-effect relationship existed. As some ellipticine derivatives were mutagenic in Saccharomyces cerevisiae despite being ineffective in Ames' assay, multiple tests should be used to check that chemotherapeutic drugs are devoid of mutagenic properties.

Isolation and physical characterization of streptomycete plasmids

Covalently closed circular DNA was isolated from a strain of Streptomyces coelicolor ATCC 10147 and from a strain of Streptomyces coelicolor subspecies flavus ATCC 19894, using two different methods. The two plasmids were of uniform monomer size: 8.9 kb for pS 10147, the plasmid from S. coelicolor ATCC 10147, and around 125 kb for the plasmid from S. coelicolor ATCC 19894. A restriction enzyme map was constructed for pS 10147, using seven enzymes. Four of the enzymes, (BamHI, Bgl,II, PvuII, and XhoI) cut pS 10147 once while PstI made two cuts. The GC content of this plasmid was calculated to be 72%. The possible utilisation of pS 10147 as a cloning vector in Streptomyces is discussed.

High frequency of yeast transformation by plasmids carrying part or entire 2-micron yeast plasmid

By using two chimeric plasmids containing yeast ura3 gene and 2-micron yeast DNA linked to the bacterial plasmid pCR1, yeast transformation of a high frequency has been achieved. The first plasmid is such that the 2-micron DNA part, in which the ura3 gene is incorporated, can be removed in one step and thus the 2-micron-ura3 sequence can be considered as a "transposable" block. In contrast, the second one bears the entire 2-micron plasmid and the ura3 gene is inserted in the bacterial plasmid part. As shown through hybridization experiments and genetic studies, the ura3 gene was maintained as a cytoplasmic element. Plasmids recovered from the yeast transformants were used to transform Escherichia coli. Their analysis by EcoRI showed that in many cases the vector had recombined with the endogenous 2-micron DNA of the recipient strain. The specific activity of orotidine 5'-monophosphate decarboxylase (coded by ura3) in yeast transformants was 10- to 30-fold higher than in the wild type.

Detection of specific DNA sequences in yeast by colony hybridization

A procedure is described for the detection of specific DNA sequences in Saccharomyces cerevisiae. This method allows a rapid screening of a large number of yeast colonies. The yeast cells of each colony, grown on nitrocellulose filters, are converted, in situ, to protoplasts by snail enzyme, and are then lysed and their DNAs are denatured and fixed on the filter. The presence of the specific DNA sequence is detected directly on the filter by hybridization with a radioactive cRNA. We have used successfully this technique to detect the presence or the absence of specific mt DNA sequences in p+, p- and p0 strains, and to detect the presence or the absence of the 2 mum DNA sequences in different strains.

A map of the restriction targets in yeast 2 micron plasmid DNA cloned on bacteriophage lambda

The 2 micron circular DNA from S. cerevisiae has been cloned on bacteriophage lambda. The two forms of circular DNA which exist in equilibrium due to recombination between inverted repeat sequences were separated as stable clones, and a map of targets for restriction endonucleases EcoRI, HindIII and HpaI was constructed. The circular DNAs isolated from a particular oligomycin resistant strain and its parent oligomycin snesitive strain were compared by restriction endonuclease analysis, and no difference was detected. The potential uses of cloned 2 micron DNA in determining the possible biological role of these plasmids are considered.

Circular DNA of a yeast episome with two inverted repeats: structural analysis by a restriction enzyme and electron microscopy

Small circular DNA molecules from genetically characterized clones of Saccharomyces cerevisiae have been studied by restriction endonuclease analysis and electron microscopy. The circular monomers (6000 bases) are shown to contain two inverted repeats of the same sequence (600 bases) situated opposite each other along the perimeter. Four endonuclease EcoRI fragments are obtained in 1:1:1:1 stoichiometry, and their sum gives a length of about 12,000 bases. The two large fragments and the two small ones differ from each other by 200 bases. We propose a model for the structure of the monomer molecule. Two classes of monomers can be generated by intramolecular recombinations within inverted repeats; they differ by the relative orientation of nonrepeated segments. The structure of dimers as predicted by the model is verified by self-renaturation of single-stranded circles. Inverted repeats in circular molecules may be related to the insertion release faculty of II episome in the chromosomes.

Ethidium bromide mutagenesis in yeast: protection by anaerobiosis

The mutagenesis by ethidium bromide, an intercalating dye, which induces the mutation from wild type (rho+) to the cytoplasmic respiratory deficient petite (rho-) in Saccharomyces cerevisiae, was studied under aerobic and anaerobic conditions. During growth of anaerobic cells at pH 6.5, ethidium bromide at a concentration of 2 mug/ml is unable to induce rho- mutants whereas under aerobic conditions the entire population is converted into rho- cells within 1 generation at the same drug concentration. With ethidium bromide 10 mug/ml 98% of the anaerobic cells are transformed into rho- in 5.5 h (more than 2 generations). In non-growing conditions, ethidium bromide 10 mug/ml has no effect in anaerobic cells. 3 h adapted cells used as control, are converted into rho- in 8 h. Increasing the ethidium bromide concentration to 20 mug/ml resulted in the appearance of some rho- mutants in the anaerobic population but marked at the same time the onset of a detectable toxic effect of the drug.