Developing Anti-Mycobacterial Therapeutics

Developing Anti-Mycobacterial Therapeutics Using a specific example discuss a possible target for the development of anti-mycobacterial therapeutics. Introduction It is estimated 1.8 billion people worldwide are infected by tuberculosis (TB)- an infectious disease caused by the etiologic agent Mycobacterium tuberculosis (Mtb) (Fullam et al., 2012). This bacterium is responsible for 2 million deaths each year and remains a continuing threat (Ouellet, Johnston and Montellano, 2011). 70-90% of individuals infected carry latent TB and never develop the disease, on the other hand, 10-30% of individuals infected can develop active TB. Over the years, the threat of TB has increased alarmingly due to the rise of multi-drug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB). The rise of MDR-TB and XDR-TB threatens to overwhelm all currently available drugs (Yam et al., 2009). Hence, the need to develop new anti-mycobacterial therapeutics. Currently, there have been numerous potential targets identified for the development of novel inhibitors. This review focuses on Mtb DNA gyrase as one such possible target (Mdluli and Spigelman, 2006). Structure and Function of DNA Gyrase DNA gyrase is an essential tetrameric enzyme involved in DNA synthesis and is understood to be the only type II topoisomerase present in Mtb. The structure of DNA gyrase consists of two subunits called GyrA and GyrB which initially form homodimers, called A2 and B2, and then form a larger heterodimer, called A2B2. The two subunits carry out different functions with the GyrA subunit carrying out cleavage of positive supercoiled DNA, while the GyrB subunit promotes ATP hydrolysis. The GyrA and GyrB subunits are products of the gyrA gene and gyrB gene. The gyrB gene is 34 base-pairs upstream to the gyrA gene and both genes are located close to the origin of replication (Unniraman, Chatterji and Nagaraja, 2002). Mtb reproduce by binary fission. During DNA replication, DNA helicase binds to the DNA double helix and begins to unwind the parental strands by utilising ATP to break the hydrogen bonds between the base-pairs. Single-stranded binding proteins help to stabilise the unwound DNA strands and prevent them from re-pairing. The point at which the two strands of DNA separate are known as replication fork. DNA polymerase then moves along each strand of DNA behind each replication fork synthesising new DNA nucleotides. As the replication fork expands, positive supercoils begin to accumulate ahead of the replication fork. For DNA replication to continue, the positive supercoils need to be removed. Supercoiling causes the DNA to form a more compact structure. DNA gyrase inserts negative supercoils to Mtb DNA. DNA gyrase binds to a circular, supercoiled DNA molecule and this alleviates one positive supercoils. Gyrase first introduces a double-stranded break in the DNA, then a segment of DNA pass es through the break to the opposite side of the gyrase protein. This movement of the DNA requires ATP hydrolysis by gyrase, and introduces a negative supercoil into the DNA molecule. Subsequently, the break in the strands is repaired and gyrase is released from the DNA. Thus, a DNA molecule with one positive supercoil now has one negative supercoil. The GyrA subunit consists of two domains called the GyrA N-terminal domain (GyrA-NTD) and GyrA C-terminal domain (GyrA-CTD). The GyrA-NTD whereas, the GyrA-CTD stabilises the binding of DNA gyrase to DNA. The residue Tyr-122 of GyrA is the site of covalent attachment to DNA. Similarly, the GyrB subunit consists of two domains called the GyrB N-terminal domain (GyrB-NTD) and GyrB C-terminal domain (GyrB-CTD). The GyrB-NTD contains the ATP binding sites. DNA gyrase is absent in eukaryotic organisms even though a less homologous enzyme does exist. Fluoroquinolones Fluoroquinolones (FQs) bind to the enzyme-DNA complex. By targeting GyrA, the duration of treatment can be shortened making it a validated target. C-terminal Domain of GyrA  Ã‚   The ability of Mtb DNA gyrase to bind and insert negative supercoils into DNA is mediated by the C-terminal domain of the GyrA subunit (GyrA-CTD). Several highly-conserved residues in GyrA-CTD were selected as potentially participating in DNA binding and bending. The use of site-directed mutagenesis resulted in the identification of four key residues which were R691A, Y577A, R745A and D669A. Substitution of these four residues resulted in a total loss of DNA binding activity by GyrA. This in turn caused a loss in supercoiling activity and relaxation. The ability of Mtb DNA gyrase to carry out its function only occurs when the GyrA subunit is combined with the GyrB subunit. Mutagenesis of R691A, Y577A, R745A and D669A not only results in loss of DNA binding activity of GyrA in the absence of GyrB, but also results in a loss of DNA binding activity in the presence of GyrB. This again led to a loss in loss in supercoiling activity and relaxation. The findings of GyrA-CTD to be essential for Mtb survival strongly promotes the idea of a new potential drug target. GyrB Subunit of Mtb DNA Gyrase The emergence of fluoroquinolone-resistant tuberculosis has meant there is a need to develop new classes of drugs targeting Mtb DNA gyrase. A lot of emphasis is often focused on targeting the GyrA subunit and this had led to research in developing novel inhibitors targeting the GyrB subunit (Medapi et al., 2015). The GyrB subunit is an attractive target for the development of anti-mycobacterial therapeutics for several reasons. Firstly, the GyrB subunit is present in a single copy. Secondly, it is an essential gene for the survival of Mtb. Thirdly, there are no alternatives to GyrB present in Mtb which could carry out the same function if it is inhibited because it contains the ATP binding pocket. Fourthly, the various strains of Mtb have a 99.9% homology for GyrB. Fifthly, GyrB exerts the same phenotypic effects on Mtb viability as FQs. Finally, the development of inhibitors targeting GyrB can be effective in shortening the duration of TB treatment and delaying the emergence of drug resistance (Chopra et al., 2012). The residues involved in ATP binding are found in the GyrB-NTD and are between residues 1-220. Moreover, two further residues, Gln335 and Lys337, found in the GyrB-CTD are also involved in ATP binding. To the date, there are hundreds of potential novel inhibitors which have been identified to inhibit the activity of GyrB. Inhibitors could be design to target the ATP-binding site or the non-ATP-binding site, however, little is known about structure of the non-ATP binding site. Novobiocin is the only approved antibiotic which has shown to inhibit the activity of GyrB. However, novobiocin has been withdrawn from the market because it is extremely toxic and has low permeability. Another drug class of drugs, aminobenzimidazole, are another strong candidate for inhibiting GyrB due to their excellent efficacy against MDR-TB strains (Chaudhari et al., 2016).

Pleasantville Essay -- essays research papers

Pleasantville Popular culture is the artistic and creative expression in entertainment and style that appeals to society as whole. It includes music, film, sports, painting, sculpture, and even photography. It can be diffused in many ways, but one of the most powerful and effective ways to address society is through film and television. Broadcasting, radio and television are the primary means by which information and entertainment are delivered to the public in virtually every nation around the world, and they have become a crucial instrument of modern social and political organization. Most of today’s television programming genres are derived from earlier media such as stage, cinema and radio. In the area of comedy, sitcoms have proven the most durable and popular of American broadcasting genres. The sitcom’s success depends on the audience’s familiarity with the habitual characters and the situations â€Å"Pleasantville† Conflicts and clashes of all sizes occur throughout the movie. The conflicts cover a wide variety of subjects, from sexual morals to discovering something new about one’s own self. The movie plays out individual struggles along with tying these conflicts in with a larger story line. The setting of the story is a 1990’s family. The parents are divorced, the son is a TV watching geek and the daughter is rebellious and popular at school. The Mom is leaving for a weekend trip, Jennifer, the daughter, has a date that night and David plans an evening home watching ...

Why the Policies Adopted by Stalin in the 1920s Differed

In many ways, Stalins policies in the 1920s differed massively from Marxist theories. For example, when Stalin had invaded Georgia, he had gone against the Marxist idea of internationalism in favour of invading Georgia and taking of the republic for the interests of Russian Nationalism. As well as this, after Lenin's death, Stalin wanted to employ a policy of ‘Socialism in One Country’. This meant that he wanted socialism in only the USSR.This again differed from Marxist ideas as it went against internationalism. It was also in contrast with Trotsky, who wanted a ‘Permanent Revolution’ across the world. The main reason Stalin did this was to agree with Lenin’s ideas, as he was trying to appear to be the natural successor to Lenin. In fact, Stalin was so intent on gaining power, that he created the cult of Lenin. This was the elevation of Lenin, his ideas and his life to an almost divine status. This was contrary to Marxist ideas of ‘leadershipâ €™.Marx believed in the dictatorship of the proletariat, which would give way to a communist Utopia where there would be no leadership and no state. Also, in 1924, Stalin wanted to keep the NEP going, even though it went against Marxism as the NEP meant that a mixed economy in which there were features of capitalism. The main reason Stalin did this was because it was a measure brought in by Lenin, and at the time, Stalin wished to make himself seem as loyal to Lenin as possible, to appear to be the natural heir.The introduction of collectivization and industrialization by Stalin were both supposed to end ideological compromise and come closer to Marxist theory. However, many historians have made it clear that these policies created a socialist Soviet Economy which was the opposite of Marx’s theory. State control of the economy was a key feature of Stalin’s totalitarian rule. To conclude, it is quite clear that Stalins theories differed greatly from that of Marx. It is also clear, however, to see that Stalins theories differed purely to try to be as much like Lenin as possible.

Gender Harassment And Heterosexist Harassment - 964 Words

In the research study â€Å"Two sides of the same coin: Gender harassment and heterosexist harassment in LGBQ work lives†, the researchers, Lilia M. Cortina and Veronica Caridad Rabelo, focused their study on people of the LGBQ (Lesbian, Gay, Bisexual, and Queer) community in the workplace. Individuals who consider themselves to be a part of the LGBQ community face many hardships in everyday life, and dealing with hate in the workplace is simply one of the many burdens placed upon them. Some are constantly harassed by coworkers because of their sexuality. They reported being stressed when in the workplace and that stress reflected in their work with their task being lower in quality. A few individuals have attempted to file complaints under Title VII which is supposed to protect individuals from sexual harassment in the place of work, but it failed to protect cases where the person filed for harassment because of sexual orientation. The goal of the study was to assist those de aling with LGBQ civil rights in the workplace and to also assist in the legal struggle to redefine what is protected under Title VII. The hypotheses, which were taken directly from the article, are as follows: Hypothesis 1 verified whether or not â€Å"LGBQ employees will be more likely to encounter multiple harassment types, referencing both sexuality and gender, rather than harassment targeting sexuality alone†. Hypothesis 2 states that â€Å"Employees reporting multiple workplace victimizations (i.e., bothShow MoreRelated`` Dude You re A Fag : Masculinity And Sexuality Essay1536 Words   |  7 Pagesand schooling construct adolescent masculinity through idioms of sexuality. In addition, the book investigates the relationships between gender and sexuality as it relates to a major social institution. Throughout the book she asks how heteronormitive and homophobic discourses, practices, and interactions produce masculine identities through focusing on gender and sexual pr actices of the students, teachers, and administrators. Pascoe identifies high school as a crucial site where masculinityRead MoreGender And Sexuality : High School Essay1618 Words   |  7 PagesC.J. Pascoe’s presentation of gender issues in high school is centered on her account of her research on River High School. The book presents the high school as a statistically average and culturally normal typical American high school. On this basis, Pascoe uses the account and its analysis to make general claims about gender and sexuality issues in American high schools. Though there comes the question of how typical River High School is terms of gender norms. Comparing the accounts of the schoolRead MoreThe Role Of Lgbtq Characters On Our Self Chosen Identities And Sexual Orientations Essay1039 Words   |  5 Pageslesbian (females sexually attracted to females); gay (males sexually attracted to males); bisexual (males/females sexually attracted to both genders); transgender (persons breaking society’s gender norms by defying r igid distinction between male and female); and, queer/questioning (persons exploring options to understand their sexual orientation and gender) (Brym Lie, 2015). Ethnography of communication is a discourse that investigates how we would react to each other’s dissimilar social and culturalRead MoreSexual Sexuality And Its Effects On Society1443 Words   |  6 Pageshomophobic remarks from several of their peers† (2016). Not only are homophobic remarks routine, but according to research conducted by the American Association of University Women, being called lesbian or gay is the most upsetting form of sexual harassment youth will experience (Iudici, A., Verdecchia, M. 2015). Iudici, A., Verdecchia, M. stated that over 90 percent of lesbians and gays teens have reported experiencing some type of verbal or physical abuse†(2015). Young people who are not heterosexualRead MoreHigh School : Gender And Gender Identity1681 Words   |  7 Pageschallenging thing to deal with especially if sexuality and gender identity are in the process. Students who are male or female are exploring in a smart and insightful ways. During C.J. Pascoe’s eighteen months of observation in a racially assorted high school, â€Å"Dude, You re a Fag† shows new light on masculinity both as a field of meaning and as a set of social practices. C. J. Pascoe s unusual approach questions masculinity as not only a gender process but also a sexual one. She proves how the wordRead MoreEssay on Theorising Heterosexism for Social Work Education1405 Words   |  6 Pagescommonly take these ideas as truth without even considering their validity. Fish (2008) states some of these assumptions such as same sex couples cannot provide the appropriate gender role models, same sex parents will raise their children to be gay, and children will be bullied because they have parents who are both of the same gender. Brennan, Craig, and Thompson (2012) state in their study that there is a link between gay and bisexual men’s obsession with thinness and muscularity and internalized homophobiaRead More A Study on Gay Parenting Essay1090 Words   |  5 PagesRauch found that gay and lesbian parents are generally similar to heterosexual parents, and, when differences were seen, they normally favored the same-sex parents. It was also found that the children of same-sex parents were not â€Å"confused about their gender identity† and were not â€Å"more likely to be homosexual† (Meezan and Rauch 103). Their children were able to develop normally in all facets of life. In another study conducted by Charlotte Patterson, she questions if there is a noticeable differenceRead MoreTitle Vii Of The Civil Rights Act Of 1964 Prohibiting Job Discrimination1141 Words   |  5 PagesTitle VII of the Civil Rights Act of 1964 prohibits job discrimination based on race, color, gender, religion and nation of origin. With the recent acceptance of marriage equality, it may leave the population doubting if they can be open and honest about their life. While, Title VII now encompasses the lesbian, gay, bisexual, transgender (LGBT) population, individuals may continue to fear their protection within the employment process. This is due to the ongoing debate within each state to implementRead MoreDiscrimination Towards Minority Groups Based On Race, Gender, And Sexual Orientation1313 Words   |  6 PagesDiscrimination towards minority groups based on race, gender, and sexual orientation has existed in our society for decades. Till this day these stereotypes and pr ejudice towards an individual’s race, sexuality, ethnicity, and background still exist. There are particular barriers such as activities and interactions with people occurring daily, as well as plenty of disadvantages for those from different cultural backgrounds other than white. The term racism comes to mind when an individual draws negativeRead MorePrejudice And Discrimination Regarding Lgbt Essay2199 Words   |  9 Pagesattitude that one may develop, (Sartore-Baldwin 2013, Duckworth 2015, Mifflin Company 2002) and discrimination is defined based on actual negative actions aimed towards individuals. Prejudices may be established due to the dislike of someone s sex, gender identity race, age, or even sexual preferences. Discrimination is based on those prejudices one develops, and that can cause one’s actions towards an individual to be negatively unjust. It is possible for an individual to adopt prejudice attitudes