Importantly, yoga did not adversely affect or improve immune or virological status in these well-controlled HIV-infected adults. Yoga appears to be a low-cost, simple to administer, safe, nonpharmacological, popular and moderately effective behavioural intervention for reducing blood pressures in HIV-infected

people. The reduction in blood pressures observed with the practice of yoga in these pre-hypertensive click here HIV-infected men and women is clinically relevant when considered in the context of anti-hypertension studies conducted in HIV-seronegative populations. Using tightly controlled dietary modification, the Dietary Approaches to Stop Hypertension (DASH) study reduced sodium intake in hypertensive participants who habitually consumed low, intermediate or high sodium levels, and reduced systolic blood pressure by 3.0, 6.2 and 6.8 mmHg [42], reductions of a similar magnitude to that observed in the current yoga study. In the PREMIER study, the DASH intervention was combined with established behavioural modifications

(weight loss by increased physical activity and reduced energy intake) in HIV-negative normo- and hypertensive African American and Caucasian men and women (mean age 50 years), and after only 6 months, systolic blood pressure was reduced by 2.1–5.7 mmHg [43], similar reductions to those observed for yoga. It is unlikely check details that changes in dietary salt affected our findings because baseline

sodium intake in the HIV-infected participants was greater than AHA recommendations (1.5 g NaCl/day [44]), but it was not different between groups and was not reduced after either intervention. Our findings support the notion PDK4 that, among traditional lifestyle modifications, the practice of yoga can be used to lower and manage systolic and diastolic blood pressures in pre-hypertensive HIV-infected people. The magnitude of the reduction in blood pressure observed here is similar to that observed in HIV-negative people with CVD risk factors who followed a yoga lifestyle intervention. Yoga tended to reduce blood pressure in studies of HIV-negative participants with the ‘metabolic syndrome’ [32], with and without previous coronary artery disease [25], and with hypertension [21]. Perhaps the practice of yoga improves vascular function/tone, and this mediates the lowering of blood pressure [25]. Conversely, in HIV-negative people with CVD risk factors, the practice of yoga appears to reduce body weight and glucose, insulin, triglyceride and proatherogenic lipoprotein levels [8–11]; beneficial effects that were not observed in the current study of people living with HIV.

The physiologies of this fungus are very different from G. zeae (Parniske, 2008). Although important for the sexual development of

G. zeae, triacylglycerides cannot move through the septal pore as lipids are stored in huge lipid bodies in the mycelia (Guenther et al., 2009). Recently, Oliver et al. (2009) proposed that fermentative intermediates (acetaldehyde, ethanol, and acetate) are generated under low oxygen stress and subsequently translocate to leaves for transpiration or recapturing of carbon sources in plants. In a similar fashion, toxic PAA pathway metabolites produced from embedded mycelia might move to aerial mycelia for recycling by ACS1 in G. zeae (Fig. S5). Expression patterns of PDC1 and ACS1 further suggest these enzymes are involved in the PAA pathway of G. zeae. Although PDC takes part in eukaryotic fermentation processes (Lehninger et al., Palbociclib molecular weight 1993), PDC1 was highly expressed in both the selleck chemical aerial mycelia and embedded mycelia. However, ACS1 was only observed in the aerial mycelia, suggesting that the upstream PAA pathway intermediates generated in the embedded mycelia are subsequently translocated to the aerial mycelia (Fig.

S5). Based on the high expression of PDC1 in aerial mycelia, we hypothesize that pyruvate and/or other glycolysis intermediates are the means of carbon translocation for lipids synthesis. In this model, glucose would not be translocated to the aerial mycelia as ACS1, which is known to be repressed by glucose, was highly expressed in the aerial mycelia (Lee et al., 2011). Growth of embedded mycelia seems to be linked to the utilization of PPA pathway intermediates in G. zeae. As mentioned previously, intermediates of the PAA pathway may move to the aerial mycelia to facilitate carbon translocation. Alternatively, they could be utilized for producing energy in the embedded mycelia (Fig. S5). Transcript levels of the PDC gene are a major determinant of ethanol production in A. nidulans, underscoring the significance of ethanol fermentation in this obligate aerobic fungus (Lockington et al., 1997). PDC mediates learn more conversion of pyruvate to acetaldehyde, which is reduced to ethanol

by alcohol dehydrogenase (Lehninger et al., 1993). Thus, PDC1 is likely important for energy production in the embedded mycelia, and deletion of this gene could result in reduced growth of embedded mycelia in G. zeae. In this study, we demonstrate that the PAA pathway is crucial for lipid production in the aerial mycelia (Fig. S5). Embedded mycelia appear to utilize PAA pathway intermediates via ethanol fermentation for proper growth. This is the first report that describes different physiological roles in the aerial and embedded mycelia for the same primary metabolic process in filamentous fungi. This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (2011-0000963).

Interestingly, the M. loti genome contains a cgmA homolog mll7848. For conciseness, mlr8375 and mll7848 are hereafter referred to as opgC and cgmA, respectively. We generated M. loti strains with mutations in opgC and/or cgmA (Table 1). We subjected cyclic β-1,2-glucans isolated from cells of the mutant strains as well as the parent strain to anion-exchange chromatography. The wild-type strain ML001 showed one neutral fraction (N) and three anionic subfractions (A1–A3) through its chromatogram, as described

previously (Kawaharada et al., 2007, 2008) (Fig. 1a). The anionic subfractions A1, A2, and A3 contain one, two, and three substituents, respectively, per glucan molecule. Phosphoglycerol and succinyl moieties contribute equally to the acidity of the molecules and appear to be distributed randomly in these subfractions (Kawaharada et al., Volasertib solubility dmso 2008). The opgC mutant YML1005 showed an elution profile similar JNK inhibitor in vivo to that for ML001, as expected from the small amount of succinyl residues in ML001 (Kawaharada et al., 2008) (Fig. 1b). The cgmA mutant YML1008, in contrast, showed considerably reduced anionic fractions, leaving a small A1 peak and, inversely, an increased neutral fraction (Fig. 1c). The wild-type cgmA allele mobilized on the plasmid (pYK88) restored anionic glucans

to the wild-type levels in YML1008 (Fig. 2). The result indicates that CgmA is required for the anionic modification of a majority of cyclic β-1,2-glucans, most likely medroxyprogesterone for glycerophosphorylation. We analyzed the residual A1 fraction from YML1008 by proton NMR spectroscopy. In the spectrum, there are no resonances attributable to glucosyl H-6 protons connecting to phosphoglycerol and H-1′ to H-3′ protons within phosphoglycerol, which were clearly detected for anionic glucans from ML001 (Kawaharada et al., 2008). Instead, a pair of triplets assigned to methylene protons (H-2′ and H-3′) of succinyl residues are intense at 2.56 and 2.60 p.p.m. (Fig. 3). The spectrum as a whole is close to that reported previously for B. abortus

cyclic β-1,2-glucans, in which succinyl residues are the only substituents (Roset et al., 2006). These results collectively indicate that the mutation in cgmA abolished all phosphoglycerol substituents of cyclic β-1,2-glucans, but that it did not affect succinyl substituents present in small amounts. The mutation in opgC abolished residual anionic fractions, i.e. succinylated cyclic β-1,2-glucans, in the cgmA-mutant background (Fig. 1c and d). Next, we attempted to test the possibility that these mutations could affect the synthesis or the export of glucan backbones. ML001 (wild type) and YML1010 (cgmA opgC double mutant) showed 0.065±0.008 (mean±SD) and 0.081±0.007, respectively, for oligosaccharides (in mg) in periplasmic extracts as expressed per milligram whole cellular proteins derived from the same amount of cells (see Materials and methods).

Table 2 shows the serovars recovered, along with their source and geographical origin, date of isolation and corresponding susceptibility patterns. In all, 19 serovars were identified, with S. Uganda (n=19), Anatum (n=14), Braenderup (n=10) and Newport (n=10) predominating, followed by serovars Carrau (n=8), Infantis (n=7), Saintpaul (n=5), Muenchen (n=4) and Rubislaw Selleckchem PXD101 (n=3). Fresno, Javiana and Senftenberg serovars were represented by two isolates each. Single isolates belonging to serovars Adelaide, Bredeney, Derby, Gaminara, Salmonella enterica ssp. enterica 6,7:d:-, Minnesota,

and Typhimurium, were also identified in this collection. No Enteritidis serovars were recovered. The most common serovars implicated in human salmonellosis in Colombia are Enteritidis and Typhimurium (Munoz et al., 2006; Wiesner et al., 2006). However, serovars identified in this study have occasionally been implicated in salmonellosis

outbreaks worldwide (Lehmacher et al., 1995; Jones et al., 2004; Gupta et al., 2007; Lang, 2008). A summary of the resistance profiles obtained for each isolate against a panel of 15 antimicrobial compounds is shown in Table 3. Forty-six percent (n=40) were resistant to at least one antimicrobial agent. Tetracycline resistance was the most common resistance find more property encountered (18.3%, n=17), followed by ampicillin resistance (17.2%; n=16), and nalidixic acid resistance (14%; n=13). Multidrug-resistant isolates (defined as resistant to three or more different drug classes) constituted 4.3% of the collection (n=4). The emergence of quinolone

resistance together with reduced ciprofloxacin susceptibility in S. enterica is increasingly observed and constitutes a major concern because infections with such isolates may cause ciprofloxacin treatment failure (Dimitrov et al., 2007). While the frequency of quinolone resistance in Salmonella is growing worldwide, in this study, 14% of the isolates were resistant to nalidixic acid, a figure that could be considered high (Marimón et al., 2004; Stevenson et al., 2007). This corresponded to the data in the SENTRY Antimicrobial Surveillance program, which reported nalidixic acid resistance of 14% in Salmonella Teicoplanin spp. isolates from Latin America during the years 1997–2004, a figure more than twofold higher than that recorded in North America (Biedenbach et al., 2006). In the case of the isolates showing resistance to quinolone-based antimicrobial compounds, an MIC for nalidixic acid of 32 μg mL−1 was recorded for two isolates, 256 μg mL−1 for three, and 1024 μg mL−1 for eight isolates. Reduced susceptibility to ciprofloxacin was noted for all 13 isolates (ranging from 0.5 to 1 μg mL−1). A summary of the MIC data is presented in Table 4. A 2–16-fold decrease in the MIC of nalidixic acid was observed In the presence of PAβN, a known efflux pump inhibitor (Table 4) with six isolates showing a 4–16-fold decrease.

bovis with both narGHJI and narK2X genes from M. tb failed to restore nitrate reductase activity in M. bovis, suggesting the involvement of additional genes/regulatory mechanisms for nitrate reduction that are absent in M. bovis. The −6T/C promoter-linked SNP enabled clear differentiation of M. tb from the other members of the M. tb complex, including M. bovis, BCG, Mycobacterium africanum and Mycobacterium microti, through a PCR-RFLP assay. Tuberculosis in humans is chiefly caused by Mycobacterium tuberculosis (M. tb). However, Mycobacterium bovis (M. bovis), the major tuberculosis pathogen in cattle, also causes disease in humans and is usually implicated in extrapulmonary tuberculosis (Wilkins

et al., 1986). Other members of the M. tb complex (MTC), such as M. bovis BCG (BCG), Mycobacterium africanum and Mycobacterium GSI-IX mouse microti, rarely cause disease in immunocompromised populations (Metchock et al., 1999; Niemann et al., 2000). Zoonotic transmission of these organisms to humans, especially of M. bovis from cattle and unpasteurized milk, is an important health concern (O’Reilly & Daborn, 1995; Shah et al., 2006). Because M. bovis is naturally resistant to pyrazinamide (Scorpio & Zhang, 1996), a first-line antituberculosis drug, therefore, differentiation of M. tb infection from M. bovis infection is of paramount importance for administering

the appropriate treatment. A classical assay that differentiates M. tb from M. bovis is its high aerobic nitrate reductase oxyclozanide activity (Virtanen, 1960). Furthermore, the nitrate Y-27632 chemical structure reductase activity of M. tb, but not M. bovis,

increases drastically upon entry into the anaerobic dormant state (Virtanen, 1960; Wayne & Doubek, 1965; Weber et al., 2000). It is thought that M. tb might survive in low-oxygen microenvironments (granulomas) by reducing nitrate to nitrite, using nitrate as a terminal electron acceptor in respiration (Wayne & Hayes, 1998; Wayne & Sohaskey, 2001). Nitrate reduction was shown to be mediated by narGHJI-encoded nitrate reductase in M. tb, but the enhanced reduction of nitrate during hypoxia was attributed to upregulation of NarK2, a putative nitrate/nitrite transporter (Sohaskey & Wayne, 2003). The inability of M. bovis and BCG to efficiently reduce nitrate under both aerobic and hypoxic conditions was ascribed to inactive narGHJI and narK2X gene/gene products (Stermann et al., 2004; Honaker et al., 2008; Sohaskey & Modesti, 2009). Single nucleotide polymorphisms (SNPs) were detected in the narGHJI promoter region (−215T/C), although it was not ruled out that other SNPs within the narGHJI operon itself could also contribute to this difference in activity (Garnier et al., 2003; Stermann et al., 2004). The response regulator DevR controls the transcription of narK2X in M. tb by binding to multiple Dev boxes (Chauhan & Tyagi, 2008a). A recent study showed that two DevR regulon genes, narK2 and narX, are inactive in M. bovis and BCG, compared with M.

Because A. hydrophila is also a component of the normal intestinal flora of healthy fish, virulence mechanisms are not well understood. Considering that fish models used for the examination of A. hydrophila genes associated with virulence have not been well defined, we established an infection model using the free-living, ciliate protozoa Tetrahymena thermophila. The expression of A. hydrophila virulence genes following infection of T. thermophila was assessed by reverse transcription-PCR and demonstrated that the aerolysin (aerA) Nivolumab research buy and Ahe2 serine protease (ahe2) genes (not present in the avirulent A. hydrophila NJ-4 strain) in the

virulent J-1 strain were upregulated 4-h postinfection. Furthermore, the presence of intact A. hydrophila J-1 within T. thermophila suggested

Selleck VX-770 that these bacteria could interfere with phagocytosis, resulting in the death of the infected protozoan 48-h postinfection. Conversely, A. hydrophila NJ-4-infected T. thermophila survived the infection. This study established a novel T. thermophila infection model that will provide a novel means of examining virulence mechanisms of A. hydrophila. Aeromonas hydrophila has been receiving increasing attention recently both as an opportunistic and as a primary pathogen of both humans and aquatic and terrestrial animals (Bi et al., 2007). Aeromonas hydrophila pathogenesis is mediated by various cell bound and secreted virulence factors including aerolysin (Singh et al., 2009), cytotoxic enterotoxin (Chopra et al., 2000), extracellular serine protease Fenbendazole (Cascon et al., 2001), elastase (Cascon & Yugueos,

2000) and S-layer (Murray et al., 1988), which can play a role in affecting disease severity. However, the precise pathogenesis mechanism is not known. The pathogenesis resulting from A. hydrophila infections might be not exclusively virulence factor mediated and can also be affected by host species resistance mechanisms. In order to develop more effective anti-infective therapies, it is important to study the pathogenesis mechanism at the cellular and molecular levels using adequate host organisms. Although fish are excellent models for assessing the lethal dose 50% of A. hydrophila (Rodriguez et al., 2008) or for examining host immune responses (Rodriguez et al., 2009), they are not ideal for dissecting host–pathogen interactions at the molecular level (Pradel & Ewbank, 2004). Many model organisms have been used to study bacterial pathogenesis. For instance, the nematode Caenorhabditis elegans and the insect Drosophila melanogaster or even unicellular Dictyostelium discoideum amoebae have proven to be useful hosts to measure bacteria virulence (Kurz & Ewbank, 2007). Previously, the amoeba D.

Traditionally pharmacists actively recruit patients to medicines use reviews, designed to address adherence through information provision, which have had variable success. Encouraging patients to identify their information needs and self-present for an MUR may improve patient satisfaction and service outcomes. Using previous evidence, a card was developed to encourage patients to identify their any information needs and seek support through an MUR. The aim of this pilot study was to implement the card and test both its acceptability to patients and pharmacists and identify its potential for enhancing service impact. Institutional ethical approval

was obtained for this service

evaluation. The patient card asked whether they were able to answer any of five questions about their medicines (side effects, see more overdose and under dose, interactions, the medicine’s effect and getting the best out of the medicine). All pharmacies in two adjacent counties belonging to one pharmacy chain participated in the evaluation for a 12 week period. Pharmacies in one county (implementation) distributed the cards with repeat medicines for patients who met the criteria for an MUR. Pharmacies in the adjacent county (comparison) did not use the cards. All patients identified as self-presenting for an MUR as a result of receiving a card MLN0128 datasheet were given a satisfaction questionnaire post consultation. Comparison

pharmacies distributed a satisfaction questionnaire to the first four MUR patients each week. Pharmacists were not asked to keep track of the number of patients given a card or approached to complete the questionnaire. The questionnaire was developed using two previously validated tools assessing satisfaction with information provision (SIMS) and adherence (MMAS-4). The questionnaire also contained demographic questions and a space for free-type comments. The questionnaire had been used in a previous study and was not piloted before implementation. Pharmacists in the implementation area were interviewed at the end of the study to obtain their thoughts on the use of the cards and was analysed using a framework very approach. Twenty-two implementation and 11 comparison pharmacies participated and cards were actively given out in five pharmacies. 81 questionnaires were returned to the university. Table 1 compares the data received from the two groups and illustrates the relationship between the use of the identification cards and both satisfaction and adherence. Table 1 The impact of providing identification cards to patients on medicines information and adherence   Implementation group (n = 31) Comparison group (n = 50) P-value *Fisher’s exact (n = 78); **Mann–Whitney U (n = 69); adherence measured by the MMAS-4.

, 2008), tides (Dobretsov & Qian, 2006), water depth (Webster et al., 2004), salinity and temperature (Lau et al., 2005; Chiu et al., 2006). These studies have neglected to examine the

effect that the settlement substrate has on the composition of the developing bacterial community and used artificial substrates, i.e. polystyrene dishes or glass slides only. Only two invertebrate larval settlement studies from harbour waters investigated the effect of different Rucaparib research buy substrates and showed that bacterial communities in biofilms undergo temporal shifts from more different communities during colonization and early developmental stages to more similar communities over time irrespective of the initial substrate type (Huggett et al., 2009; Chung et al., 2010). These studies were, however, limited to only

artificial substrates, i.e. glass slides coated in different chemicals to simulate different ‘wettability’ properties, deployed at one site only (Huggett et al., 2009) or subtidal biofilms on two substrates, i.e. granite and petri dishes, at one deployment time only (Chung et al., 2010). Therefore, although these studies have shed some light onto the effects of substrates on bacterial community compositions in marine biofilms, inferences on the suitability of various substrates for future studies cannot be drawn. This is especially the case for water quality bioindicator Clomifene research, where substrates are required which on the one hand simulate or reproduce naturally occurring biofilm assemblages, but drug discovery on the other hand are easy to deploy and sample and provide a standardized surface. This study therefore evaluates the effects of various substrates on the bacterial community composition in biofilms from tropical coral reef ecosystems with

the aim of providing better rationale for future bioindicator studies of water quality in these types of ecosystems. The criteria for the choice of substrate include ease of handling and removal of biofilm from the substrate, standardized size and resemblance of developed bacterial communities to those found on ‘natural’ substrates. We specifically examined bacterial community compositions using the molecular fingerprinting method terminal restriction fragment length polymorphism (T-RFLP) on two ‘artificial’ substrates, i.e. ceramic tile and glass slides, which are frequently used in aquatic biofilm studies, and two ‘naturally occurring’ substrates that were collected directly from the coral reef sampling area, i.e. coral skeletons and reef sediments. Furthermore, the study extends previous knowledge by covering a more realistic time period for indicator biofilm development (i.e. 48 days), by incorporating temporal and spatial variability.

, 2009). Based on these data, we evaluated how heme A is synthesized by T. cruzi (and the other trypanosomatids). The coding sequences for putative proteins homologous to HOS and HAS have been identified in the T. cruzi genome. One cds, Tc00.1047053511211.70, was identified as a HAS homologue (named TcCOX15 and TcCox15 for the corresponding protein). Two cds were associated with HOS (Tc00.1047053509601.59 and Tc00.1047053509767.59)

presenting a sequence identity of 98% (named TcCOX10A and TcCOX10B, and TcCox10 A and B for the corresponding protein sequences). The predicted protein sequences [TcCox10 (A and B) and TcCox15] show about 52% and 56% homology and 37% and 41% identity to their S. cerevisiae orthologues, and they are also conserved in other trypanosomatids VX-765 (Fig. 1). The multiple sequence alignment of HOSs includes the available trypanosomatid putative protoheme IX farnesyltransferase (HOS) and the S. cerevisiae Cox10 protein (Fig. 1a). The residues N196, R212, R216 and H317 (S. cerevisiae numbering), which are involved in the protein’s function (Bestwick et al., 2010), are conserved in trypanosomatid sequences (indicated in Fig. 1a). The multiple sequence alignment of HAS proteins includes the available trypanosomatid putative HAS enzymes and the S. cerevisiae Cox15

protein (Fig. 1b). The alignment shows that residues involved in HAS activity based on studies from CH5424802 cell line the Bacillus subtilis CtaA enzyme are also conserved in trypanosomatid sequences (Barros et al., 2001; Hederstedt et al., 2005). Calpain Figure 1b shows the residues

H169, H245 and H393 from S. cerevisiae numbering, which correspond to CtaA H60, H123 and H216, respectively. Both T. cruzi putative proteins present eight predicted TMs, which is compatible with this type of protein (Fig. 1). The cds for TcCOX10 and TcCOX15 were amplified by PCR using total genomic DNA as the template and introducing a 3′-coding sequence for a 6xHis tag. As TcCOX10 A and B cds show 98% identity, the primers designed recognize both of them equally. The amplified product for TcCOX10 coincided with the Tc00.1047053509601.59 (TcCOX10A) sequence, and is named TcCOX10 and TcCox10 hereafter for the corresponding protein. Both cds (TcCOX10 and TcCOX15) were subcloned into yeast expression vectors and used to transform yeast cells lacking the corresponding genes (Δcox10 and Δcox15). These knockout cells present a respiration-deficient phenotype due to the absence of heme A production and consequently a functionally inactive CcO complex (Nobrega et al., 1990; Glerum et al., 1997). This deficiency impairs the growth in a nonfermentable carbon source such as glycerol–ethanol, but they all can grow in a media containing a fermentable carbon source as glucose. Their respiratory function was restored once TcCOX10A.6xHIS or TcCOX15.6xHIS was expressed in Δcox10 or Δcox15, respectively (Fig. 2a). Both mutants were also transformed with plasmids containing the corresponding S.

Results in Fig. 4b show that in the absence of a plasmid encoding MalI, as expected, these insertions have but small effects on MelR-dependent repression of the melR promoter. However, with plasmid pACYC-malI, which encodes MalI, there is a clear small significant relief of repression with the TB334I-1 and TB334I-2 selleck inhibitor fragments carrying one or two MalI operator elements, but no relief with the control TB31, TB33 or TB334 fragments. The expression of many transcription repressors is autoregulated by repression (Browning & Busby, 2004). Kahramanoglou et al. (2006) proposed a two-state model for MelR in which, in the absence of its ligand, melibiose, MelR acts as an autorepressor of

its own production by repressing the melR promoter. Samarasinghe et al. (2008) showed that this repression was due to the formation of a nucleoprotein complex involving four MelR subunits. Here, we report that it is possible to construct simpler derivatives of the melR promoter where only two MelR targets are needed for efficient repression (Fig. 1), and there are clear parallels between this and AraC-dependent repression at the araC–araBAD intergenic region, where repression is dependent on interaction between two AraC subunits bound to targets separated by 210 base

pairs (Schleif, 2010). An explanation for the observed repression with the TB33 fragment is that MelR subunits bound at the upstream and downstream DNA targets interact and result in loop formation, as for AraC. However, there appears to be more flexibility in how the high throughput screening two DNA sites for MelR Resveratrol can be juxtaposed, compared to AraC. Hence, AraC-dependent repression is disrupted by +5 base pair insertions (Lee & Schleif, 1989), whilst MelR-dependent repression is not (Fig. 2). The simplest explanation for this would be that the linker joining the N- and C-terminal domains is more flexible in MelR than in AraC. This flexibility is underscored by the experiment in Fig. 4 where MalI binding failed to completely disrupt repression. This experiment also argues that the mechanism of MelR-dependent repression with TB33 is different to the mechanism operating at the more complex

wild type melibiose operon regulatory region in TB22 (Fig. 1), where repression depends on the formation of a nucleoprotein complex. In the new constructs described here, efficient repression of the melR promoter by MelR requires interaction between MelR bound immediately adjacent to the transcript start and upstream-bound MelR, and this can be subverted by the insertion of a supplementary DNA site for MelR (Fig. 3). Hence, efficient repression results from two, but not from three, DNA sites for MelR. Our experiments underline the diversity of protein–DNA architectures that can be responsible for transcription repression. This work was supported by the UK BBSRC with a project grant to S.J.W.B. and a summer studentship to D.D.