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Olfactomedin 1 (OLFM1) is a secreted glycoprotein and member of the olfactomedin protein family, which is preferentially expressed in various areas throughout the central nervous system. To learn about the functional properties of OLFM1 in the eye, we investigated its localization in the mouse and pig eye. In addition, we analyzed the ocular phenotype of Olfm1 mutant mice in which 52 amino acids were deleted in the central part (M2 region) of OLFM1. OLFM1 was detected in cornea, sclera, retina, and optic nerve of both wild-type and Olfm1 mutant littermates. By immunohistochemistry and double labeling with the lectin peanut agglutinin, OLFM1 was found in the interphotoreceptor matrix (IPM) of mouse and pig retina where it was directly localized to the inner segments of photoreceptors. Western blotting confirmed the presence of the OLFM1 isoforms pancortin 1 (BMY) and pancortin 2 (BMZ) in the IPM. The retinal phenotype of Olfm1 mutant mice did not obviously differ from that of wild-type littermates. In addition, outer nuclear layer (ONL) and total retinal thickness were not different, and the same was true for the area of the optic nerve in cross sections. Functional changes were observed though by electroretinography, which showed significantly lower a- and b-wave amplitudes in Olfm1 mutant mice when compared to age-matched wild-type mice. When light damage experiments were performed as an experimental paradigm of photoreceptor apoptosis, significantly more TUNEL-positive cells were observed in Olfm1 mutant mice 30 h after light exposure. One week after light exposure, the ONL was significantly thinner in Olfm1 mutant mice than in wild-type littermates indicating increased photoreceptor loss. No differences were observed when rhodopsin turnover or ERK1/2 signaling was investigated. We conclude that OLFM1 is a newly identified IPM molecule that serves an important role for photoreceptor homeostasis, which is significantly compromised in the eyes of Olfm1 mutant mice.

High-throughput MS/MS was used to identify proteins secreted by Fusarium graminearum (Gibberella zeae) during growth on 13 media in vitro and in planta during infection of wheat heads. In vitro secreted proteins were collected from the culture filtrates, and in planta proteins were collected by vacuum infiltration. A total of 289 proteins (229 in vitro and 120 in planta) were identified with high statistical confidence. Forty-nine of the in planta proteins were not found in any of the in vitro conditions. The majority (91-100%) of the in vitro proteins had predicted signal peptides, but only 56% of the in planta proteins. At least 13 of the nonsecreted proteins found only in planta were single-copy housekeeping enzymes, including enolase, triose phosphate isomerase, phosphoglucomutase, calmodulin, aconitase, and malate dehydrogenase. The presence of these proteins in the in planta but not in vitro secretome might indicate that significant fungal lysis occurs during pathogenesis. On the other hand, several of the proteins lacking signal peptides that were found in planta have been reported to be potent immunogens secreted by animal pathogenic fungi, and therefore could be important in the interaction between F. graminearum and its host plants.

Coupling anticancer drugs to synthetic polymers is a promising approach of enhancing the antitumor efficacy and reducing the side-effects of these agents. Doxorubicin maleimide derivatives containing an amide or acid-sensitive hydrazone linker were therefore coupled to alpha-methoxy-poly(ethylene glycol)-thiopropionic acid amide (MW 20000 Da), alpha,omega-bis-thiopropionic acid amide poly(ethylene glycol) (MW 20000 Da) or alpha-tert-butoxy-poly(ethylene glycol)-thiopropionic acid amide (MW 70000 Da) and the resulting polyethylene glycol (PEG) conjugates isolated through size-exclusion chromatography. The polymer drug derivatives were designed as to release doxorubicin inside the tumor cell by acid-cleavage of the hydrazone bond after uptake of the conjugate by endocytosis. The acid-sensitive PEG conjugates containing the carboxylic hydrazone bonds exhibited in vitro activity against human BXF T24 bladder carcinoma and LXFL 529L lung cancer cells with IC70 values in the range 0.02-1.5 microm (cell culture assay: propidium iodide fluorescence or colony forming assay). In contrast, PEG doxorubicin conjugates containing an amide bond between the drug and the polymer showed no in vitro activity. Fluorescence microscopy studies in LXFL 529 lung cancer cells revealed that free doxorubicin accumulates in the cell nucleus whereas doxorubicin of the acid-sensitive PEG doxorubicin conjugates is primarily localized in the cytoplasm. Nevertheless, the acid-sensitive PEG doxorubicin conjugates retain their ability to bind to calf thymus DNA as shown by fluorescence and visible spectroscopy studies. Results regarding the effect of an acid-sensitive PEG conjugate of molecular weight 20000 in the chorioallantoic membrane (CAM) assay indicate that this conjugate is significantly less embryotoxic than free doxorubicin although antiangiogenic effects were not observed.

l-Carrageenan is a polysulphated carbohydrate that antagonises some heparin-binding growth factors. We assessed the effect of l-carrageenan on the proliferation of a panel of cell lines, some of which require heparin-binding growth factors for mitogenesis. The importance of growth factor antagonism for the anti-proliferative activity was also determined. Cell proliferation was determined by cell counts and a tetrazolium dye (MTT) assay, and DNA synthesis was determined by thymidine incorporation. The proliferation of the basic fibroblast growth factor (bFGF)-dependent endothelial cell line FBHE was inhibited by daily administration of l-carrageenan in a dose-dependent manner [concentration inhibiting cell growth by 50% (IC50 value), approx. 0.5 microgram/ml]. However, excess bFGF did not reverse the inhibitory effect. DNA synthesis was completely inhibited by concentrations of l-carrageenan that nonetheless allowed significant protein synthesis to occur. The proliferation of the androgen-dependent prostate-carcinoma cell line LNCaP was also inhibited by l-carrageenan (IC50 value, 5.5 micrograms/ml) and the cells were arrested at the G1/S boundary. l-Carrageenan inhibited DNA synthesis in MCF-7 cells stimulated by bFGF and transforming growth factor alpha (TGF alpha) but not in those stimulated by insulin-like growth factor 1 (IGF-1). Blocking IGF-1-mediated DNA synthesis with anti-IGF-1 receptor antibody alpha IR3 enhanced the inhibitory activity of l-carrageenan against MCF-7 cells grown in serum. A number of other transformed and non-transformed cell lines were either partially inhibited or not inhibited by l-carrageenan. l-Carrageenan had low anti-coagulant activity. l-Carrageenan is a selective anti-proliferative agent and warrants further investigation for anti-angiogenic therapy (in view of its activity against endothelial cells) and for the treatment of androgen-dependent prostate cancer.

Human papillomavirus (HPV) was detected by using two sets of deoxyribonucleotide primers for differentiating between 'low-risk' types (HPV11 and HPV6) and 'high-risk' (hri) types (HPV16, HPV18 and HPV33). A new application of the Chemiprobe method for labeling DNA was used to detect products of the polymerase chain reaction (PCR) from 36 cervical biopsies. This method, first demonstrated by Uchimura et al. (submitted), is based on the sulfonation of a polycytidylic acid tail of 5-20 monomers attached to the 5' end of either one or both of the PCR primers. This procedure can increase the sensitivity of detection of PCR products more than 100-fold with respect to ethidium bromide (EtdBr) staining. Various methods were used to detect hri HPV DNA in the 36 clinical samples. The number of positive results obtained was as follows, two by Southern-blot hybridization; five by PCR amplification followed by electrophoresis and detection of products by EtdBr staining; six by PCR amplification using one or two sulfonated C-tailed primers followed by electroblotting and immunoenzymatic visualization; and five by hybridization of sulfonated genomic viral recombinant with a PCR product immobilized on a membrane. The yield of the PCR product was significantly greater when one of the primers was C-tailed than when both or neither of the primers were C-tailed. PCR employing sulfonated C-tailed oligo primers is very specific and sensitive, and the entire procedure can be employed as a nonradioactive substitute for radioactive dot-blot or Southern-blot hybridization procedures, routinely used for detection of HPV in clinical samples.

openaire: EC/H2020/788489/EU//BioELCell Funding Information: This work was supported by the National Key Research and Development Program of China ( 2019YFC1905900 ), the National Natural Science Foundation of China ( 31870566 ), the Jinan Innovation Team ( 2021GXRC023 ), and Taishan Scholars Program . OJR and ZD are grateful for the support received from the Canada Excellence Research Chair Program ( CERC-2018-00006 ), the Canada Foundation for Innovation (Project number 38623 ) and the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Program (grant agreement No 788489 ). Publisher Copyright: © 2022 Water waves are viable low-carbon and renewable sources of power that can be optionally combined with triboelectric nanogeneration (TENG). Herein, we report on the synthesis of a TENG device based on green wrinkled paper tribolayers (W-TENG) assembled in grids (G-TENG) with channels that enable contact-separation modes involving metal balls that roll in phase with the waves. The paper's wrinkle wavelength and amplitude were adjusted by using a crepe blade at a given angle with respect to a drying cylinder, as well as the speed and torque. Polar hierarchical superhydrophobic cellulose micro/nanostructures, proposed as positive tribolayers with enhanced contact area and triboelectric density. The negative (biodegradable) tribolayers were prepared by electrospinning aqueous suspensions of polyvinyl alcohol and poly (ethylene oxide) reinforced with cellulose nanofibers. The charge transfer by the W-TENG reached up to 40 nC in air and retained 27 nC under 85 % relative humidity, ~5 and 7 times higher than those measured in planar TENG counterparts. A G-TENG array charging time (100-μF capacitor) of ~188 s was measured when the voltage of the capacitor raised to ~1.5 V. Overall, we introduce a new, scalable TENG system that is demonstrated for its remarkable ability to harvest blue energy.

International audience; Epidemiological studies on statin use in relation to skin cancer risk are scarce and yielded conflicting results. We explored this association in Etude Epidémiologique auprès de femmes de l'Education Nationale, a prospective cohort of French women born in 1925–1950. Health and lifestyle data were self-reported biennially and matched with drug reimbursement data, allowing the identification of participants’ statin use since 2004. Multivariable cause-specific hazards regression models adjusted for skin cancer risk factors estimated hazard ratios with 95% confidence intervals. Over 2004–2014, 455 cutaneous melanoma, 1,741 basal cell carcinoma, and 268 squamous cell carcinoma cases were ascertained among 62,473 women. Compared with never use, there were no associations between ever use of statins and melanoma (hazard ratio = 1.16, 95% confidence interval = 0.94–1.44) or squamous cell carcinoma (hazard ratio = 0.89, 95% confidence interval = 0.66–1.19) risks and a decrease in basal cell carcinoma risk with ever use of statins (hazard ratio = 0.89, 95% confidence interval = 0.79–0.996). We found no trend of increasing or decreasing risks with dose, duration of use, time since first use, or age at first use and no statistically significant effect modification by pigmentary traits or residential UVR exposure. Because of the limited number of studies evaluating the associations between the use of statins and the risks of melanoma, basal cell carcinoma, and squamous cell carcinoma, these findings would deserve further investigation in other settings.

The World Health Organization has recommended performing at least 60 min a day of moderate-to-vigorous physical activity (MVPA) and reducing sedentarism in children and adolescents to offer significant health benefits and mitigate health risks. Physical fitness and sports practice seem to improve oxidative stress (OS) status during childhood. However, to our knowledge, there are no data regarding the influence of objectively-measured physical activity (PA) and sedentarism on OS status in children and adolescents. The present study aimed to evaluate the influence of moderate and vigorous PA and sedentarism on OS and plasma total antioxidant capacity (TAC) in a selected Spanish population of 216 children and adolescents from the GENOBOX study. PA (light, moderate, and vigorous) and sedentarism (i.e., sedentary time (ST)) were measured by accelerometry. A Physical Activity-Sedentarism Score (PASS) was developed integrating moderate and vigorous PA and ST levels. Urinary 8-hydroxy-20-deoxyguanosine (8-OHdG) and isoprostane F2 (F2-IsoPs), as markers of OS, were determined by ELISA; and TAC was estimated by colorimetry using an antioxidant kit. A higher PASS was associated with lower plasma TAC and urinary 8-OHdG and F2-IsoPs, showing a better redox profile. Reduced OS markers (8-OHdG and F2-IsoPs) in children with higher PASS may diminish the need of maintaining high concentrations of antioxidants in plasma during rest to achieve redox homeostasis., Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica (I + D + I), Instituto de Salud Carlos III-Health Research Funding (FONDOS FEDER) PI11/02042 PI11/02059 PI11/01425 PI16/00871 PI16/01301 PI16/01205, RETIC (Redes temáticas de investigación cooperativa) Red SAMID RD12/0026/0015, Instituto de Salud Carlos III European Commission IFI17/00048, Research Plan of the Vice-Rectorate of Research and Transfer of the University of Granada, Spain

Background-\ud \ud The limited available literature suggests that sleep problems are linked to an increased risk of mild cognitive impairment (MCI). However, this association has been little studied to date in low-income settings.\ud \ud Objective-\ud \ud To investigate the association between sleep problems and MCI in a large sample of adults from six low-and middle-income countries (LMICs).\ud \ud Design-\ud \ud Cross-sectional.\ud \ud Setting-\ud \ud Study on Global Ageing and Adult Health (SAGE).\ud \ud Subjects-\ud \ud 32,715 individuals aged ≥50 years with preservation in functional abilities [age range 50–114 years; 51.7% females].\ud \ud Methods-\ud \ud MCI was defined using the National Institute on Aging-Alzheimer's Association criteria. Sleep problems were assessed by the question “Overall in the last 30 days, how much of a problem did you have with sleeping, such as falling asleep, waking up frequently during the night or waking up too early in the morning?” and categorized as “None”, “Mild”, “Moderate”, “Severe/Extreme”. Multivariable logistic regression analysis and meta-analysis were conducted.\ud \ud Results-\ud \ud Compared to no sleep problems, mild, moderate, and severe/extreme sleep problems were associated with significant 1.40, 1.83, and 2.69 times higher odds for MCI with similar associations being observed between age groups and sex. Severe/extreme sleep problems were positively associated with MCI (i.e., OR > 1) in the six countries studied with the overall estimate being OR = 1.80 (95% CI = 1.50–2.16), and a low level of between-country heterogeneity was observed (I2 = 28.2%).\ud \ud Conclusions-\ud \ud Sleep problems were associated with higher odds for MCI. Interventions to improve sleep quality among middle-aged and older adults in LMICs may be an effective strategy in reducing risk of MCI and dementia.

International audience; Thrombopoietin (Tpo) and its receptor (Mpl) are the principal regulators of early and late thrombopoiesis and hematopoietic stem cell maintenance. Mutations in MPL can drastically impair its function and be a contributing factor in multiple hematologic malignancies, including congenital amegakaryocytic thrombocytopenia (CAMT). CAMT is characterized by severe thrombocytopenia at birth, which progresses to bone marrow failure and pancytopenia. Here we report unique familial cases of CAMT that presented with a previously unreported MPL mutation: T814C (W272R) in the background of the activating MPL G117T (K39N or Baltimore) mutation. Confocal microscopy, proliferation and surface biotinylation assays, co-immunoprecipitation, and western blotting analysis were used to elucidate the function and trafficking of Mpl mutants. Results showed that Mpl protein bearing the W272R mutation, alone or together with the K39N mutation, lacks detectable surface expression while being strongly colocalized with the endoplasmic reticulum (ER) marker calreticulin. Both WT and K39N-mutated Mpl were found to be signaling competent, but single or double mutants bearing W272R were unresponsive to Tpo. Function of the deficient Mpl receptor could be rescued by using 2 separate approaches: (1) GRASP55 overexpression, which partially restored Tpo-induced signaling of mutant Mpl by activating an autophagy-dependent secretory pathway and thus forcing ER-trapped immature receptors to traffic to the cell surface; and (2) CRISPR-Cas9 gene editing used to repair MPL T814C mutation in transfected cell lines and primary umbilical cord blood–derived CD34+ cells. We demonstrate proof of principle for rescue of mutant Mpl function by using gene editing of primary hematopoietic stem cells, which indicates direct therapeutic applications for CAMT patients.

Clustered regularly interspaced short palindromic repeat (CRISPR)-Cas systems are well-known acquired immunity systems that are widespread in archaea and bacteria. The RNA-guided nucleases from CRISPR-Cas systems are currently regarded as the most reliable tools for genome editing and engineering. The first hint of their existence came in 1987, when an unusual repetitive DNA sequence, which subsequently was defined as a CRISPR, was discovered in the Escherichia coli genome during an analysis of genes involved in phosphate metabolism. Similar sequence patterns were then reported in a range of other bacteria as well as in halophilic archaea, suggesting an important role for such evolutionarily conserved clusters of repeated sequences. A critical step toward functional characterization of the CRISPR-Cas systems was the recognition of a link between CRISPRs and the associated Cas proteins, which were initially hypothesized to be involved in DNA repair in hyperthermophilic archaea. Comparative genomics, structural biology, and advanced biochemistry could then work hand in hand, not only culminating in the explosion of genome editing tools based on CRISPR-Cas9 and other class II CRISPR-Cas systems but also providing insights into the origin and evolution of this system from mobile genetic elements denoted casposons. To celebrate the 30th anniversary of the discovery of CRISPR, this minireview briefly discusses the fascinating history of CRISPR-Cas systems, from the original observation of an enigmatic sequence in E. coli to genome editing in humans.

International audience; We characterized YabT, a serine/threonine kinase of the Hanks family, from Bacillus subtilis. YabT is a putative transmembrane kinase that lacks the canonical extracellular signal receptor domain. We demonstrate that YabT possesses a DNA-binding motif essential for its activation. In vivoYabT is expressed during sporulation and localizes to the asymmetric septum. Cells devoid of YabT sporulate more slowly and exhibit reduced resistance to DNA damage during sporulation. We established that YabT phosphorylates DNA-recombinase RecA at the residue serine 2. A non-phosphorylatable mutant of RecA exhibits the same phenotype as the yabT mutant, and a phosphomimetic mutant of RecA complements yabT, suggesting that YabT acts via RecA phosphorylation in vivo. During spore development, phosphorylation facilitates the formation of transient and mobile RecA foci that exhibit a scanning-like movement associated to the nucleoid in the mother cell. In some cells these foci persist at the end of spore development. We show that persistent RecA foci, which presumably coincide with irreparable lesions, are mutually exclusive with the completion of spore morphogenesis. Our results highlight similarities between the bacterial serine/threonine kinase YabT and eukaryal kinases C-Abl and Mec1, which are also activated by DNA, and phosphorylate proteins involved in DNA damage repair.

International audience; A scarcity of favourable habitats and introgression from exotic cultivars are two major threats to black poplars (Populus nigra L.) in Europe. Natural vegetative propagation contributes to maintenance of the species in areas where seedling recruitment is limited. Exhaustive sampling of all mature trees in a natural P. nigra stand (413 individuals at recorded positions), genotyping at 11 SSR loci, and a standardized analysis framework resulted in a precise description of clonality in terms of (a) frequency, (b) spatial growth form, and (c) impacts on the overall spatial genetic structure (SGS). The high proportion of replicated genotypes detected resulted in a genotypic richness (R) of 0.47. Up to 18 ramets were found per multilocus lineage (MLL), but 95% of MLLs contained fewer than five ramets (Pareto index β = 1.07). No significant difference in vegetative propagation potential was found between genders. Uneven spatial distribution of ramets, with clustering of clonal ramets (aggregation index A c = 0.62) and near-zero intermingling between MLLs (clonal dominance index D c = 0.99), resulted in a ‘phalanx’ clonal growth form, explaining most of the SGS observed over short distances (0–20 m, Sp = 0.0324). Although they did not exhibit the typical columnar shape of the Lombardy poplar (P. nigra var. italica), five trees were found to be probable F1 hybrids of this old and widely distributed cultivar.

International audience; AIMS: A novel chimeric-truncated form of t-PA with improved fibrin affinity and resistance to PAI was successfully produced in CHO expression system during our previous studies. Considering advantages of prokaryotic expression systems, the aim in this study was to produce the novel protein in E.coli (BL21) strain and compare the protein potency in batch and fed-batch processes. METHODS AND RESULTS: The expression cassette for the novel t-PA was prepared in pET-28a(+). The E.coli expression procedure was compared in traditional batch and newly developed fed batch; EnBase® Flo system. The protein was purified in soluble format and potency results were identified using Chromolize t-PA assay kit. The fed-batch fermentation mode, coupled with a Ni-NTA affinity purification procedure under native condition resulted in higher amounts of soluble protein, and about a 30% of improvement in the specific activity of the resulted recombinant protein (46.66 IU mg(-1) ) compared to traditional batch mode (35.8 IU mg(-1) ). CONCLUSIONS: Considering the undeniable advantages of expression in the prokaryotic expression systems such as E.coli for recombinant protein production, applying alternative methods of cultivation is a promising approach. In this study, fed-batch cultivation methods showed the potential to replace miss folded formats of protein with proper folded, soluble form with improved potency. SIGNIFICANCE AND IMPACT OF STUDY: E.coli expression of recombinant proteins, still counts for nearly 40% of marketed biopharmaceuticals. The major drawback of this system is the lack of appropriate post translational modifications, which may cause potency loss/decline. Therefore, applying alternative methods of cultivation as investigated here is a promising approach to overcome potency decrease problem in this protein production system. © 2012The Authors Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

Background Reverse engineering in systems biology entails inference of gene regulatory networks from observational data. This data typically include gene expression measurements of wild type and mutant cells in response to a given stimulus. It has been shown that when more than one type of experiment is used in the network inference process the accuracy is higher. Therefore the development of generally applicable and effective methodologies that embed multiple sources of information in a single computational framework is a worthwhile objective. Results This paper presents a new method for network inference, which uses multi-objective optimisation (MOO) to integrate multiple inference methods and experiments. We illustrate the potential of the methodology by combining ODE and correlation-based network inference procedures as well as time course and gene inactivation experiments. Here we show that our methodology is effective for a wide spectrum of data sets and method integration strategies. Conclusions The approach we present in this paper is flexible and can be used in any scenario that benefits from integration of multiple sources of information and modelling procedures in the inference process. Moreover, the application of this method to two case studies representative of bacteria and vertebrate systems has shown potential in identifying key regulators of important biological processes.

International audience; Background : Many large secreted gel-forming mucins contain multiple copies of a "naked" cysteine-enriched domain (CYS domain) that interrupt or are adjacent to mucin domains (Ser/Thr/Pro regions). There is less similarity of homologous CYS sequences between species than there is across CYS repeats within species. These CYS domains are likely implicated in reversible mucin-mucin interactions that play a central role in mucus properties. Results : The use of multiple genome sequences in a comparative analysis of CYS sequences identified new mucins containing the CYS domain in various species. Furthermore, analysis showed that this domain is at least 650 million-year old and that CYS sequences evolved under strong selective pressure in concerted fashion in all species examined by two mechanisms that never coexist within a given gene: either multiplication of exons encoding CYS modules or successive intra-exonic duplications. Conclusion : The CYS sequences appear to have undergone concerted evolution with a high selective pressure to conserve cysteine and other amino acid residues. This domain is the best-conserved domain in secreted mucins pointing toward an important common function in many different organisms.

International audience; The self-activation of initiator caspases is dependent on their oligomerization driven by interaction with the death fold domains (DFD) of adaptor proteins. Here, we show that the E2 protein of human papillomavirus type 18 triggers apoptosis by assembling cytoplasmic filaments together with caspase 8, in which its efficient self-activation occurs. The E2 protein binds directly to the death effector domains (DED) of caspase 8 through non-DFD interaction. This interaction is independent of FADD, but it can cooperate with FADD homotypic binding to caspase 8 to induce its oligomerization; hence cell death, while it is antagonized by competitive binding of MC159 FLICE inhibitory protein. The amino-terminal domain of E2 contains a 27 amino-acid a-helix, which is necessary and sufficient to induce caspase oligomerization and cell death. Our results provide evidence for adaptor-independent oligomerization of caspase 8, mediated by non-DFD direct interactions with the HPV18 E2 protein, thus deciphering a new pathway for caspase 8 activation.

Shigella flexneri 2a is known to express the H-NS nucleoid-structuring protein and the paralogous protein StpA. Using bioinformatic analysis we have now discovered a third member of the H-NS protein family, Sfh (S higella f lexneri H-NS-like protein), in strain 2457T. This protein is encoded by the sfh gene, which is located on a high-molecular-mass plasmid that is closely related to the self-transmissible plasmid R27. When expressed in Escherichia coli, the Sfh protein can complement an hns null mutation, restoring wild-type Bgl, porin protein, and mucoidy phenotypes, and wild-type expression of the fliC and proU genes. While a knockout mutation in the sfh gene alone had no effect on the expression of virulence genes in S. flexneri, an additive effect on virulence gene derepression was seen when the sfh lesion was combined with a mutation in hns. Over-expression of the sfh gene repressed expression of the VirB virulence regulatory protein and transcription of a VirB-dependent structural gene promoter. The purified Sfh protein bound specifically to DNA sequences containing the promoters of the virF and virB virulence regulatory genes. These findings show that Sfh has the ability to influence genetic events beyond the genetic element that encodes it, including the expression of the S. flexneri virulence genes. They raise the possibility of a triangular relationship among three closely related proteins with broad consequences for genetic events in the bacterium that harbours them.