Unraveling the molecular mechanism of DNA binding by Transcription-activator like effectors
Sequence-specific DNA targeting of nucleases, recombinases and transcriptional activators is a powerful tool to manipulate the sequence or regulate the expression of the gene of interest. While Zinc fingers specific to DNA trinucleotides, coupled to different effector domains have been employed for targeted manipulation of the genome with considerable success, we are limited by the off-target toxicity caused by trinucleotide specific zinc fingers. Recently, it has been shown that Xanthomonas secreted virulence factors called transcription-activator like effectors (TALEs), which contain 1.5 to 33.5 tandem repeats bind sequence
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In the crystal structure presented by Deng et al., the central region of an engineered TALE dHax3 shows a super helical assembly with an external diameter of 60A and a pitch also of 60A with 11 repeat domains per helical turn. This structure strongly suggests that dHax3 wraps around the DNA helix. Each repeat of dHax3 consists of 34 amino acids, 3 to 11 of which form a short helix ‘a’ and 15 to 33 form helix ‘b’. These two helices are connected by the RVD loop that contains residue 12, usually a His or Asn, that stabilizes the local conformation of RVD loop and residue 13 that recognizes a DNA base. In dHax3, residue 14 is shown to be a conserved Glycine. Helices ‘a’ and ‘b’ stack together using Van der Waals interactions. Interestingly, the pitch of dHax3 in DNA-free form is 60A but goes down to 35A when bound to the DNA but maintains 11 repeat domains per helical turn. This compression of TALEs is attributed to the conformational plasticity of residues 23 to 34 of the repeat domains. The inner region of the repeat domains is electrostatically positively charged with residues like Lys 16 and Gln 17 on helix ‘b’, which can hydrogen bond with the negatively charged phosphate groups of the DNA. The hypervariable di-residues HD recognize base ‘C’, NS recognize base ‘A’ and NG recognize base ‘T’. In the case of NGà T recognition, glycine at position 13 helps accommodate the 5’ methyl
The article that I found discusses how DNA evidence was used to convict a suspect after twenty years under investigation. The homicide case was recently closed on the rape and murder of Ophelia Preston, a 24 year-old female in Milwaukee County. Preston was deaf and mute and also suffered from a cocaine addiction, which led her to meeting Melvin Lee Jones.
This book has been molded to be a breakdown of how various fields in science have progressed over centuries as mankind has advanced. The book starts off introducing the idea that the telling of natural history has changed numerous times as humans have evolved. We also learn to agree that our knowledge has been shaped by the tools available and the perceptions of its users. In the earliest stages of life, Muehlbauer states “…observers of the natural world had only their senses to work with, and were limited to visual, auditory, tactile, and olfactory descriptions perceived by the unaided
Discoveries in DNA, cell biology, evolution, biotechnology have been among the major achievements in biology over the past 200 years with accelerated discoveries and insights over the last 50 years. Consider the progress we have made in these areas of human knowledge. Present at least three of the discoveries you find to be most important and describe their significance to society, health, and the culture of modern life.
This paper explores the history and some interesting facts about DNA. The last couple centuries have seen an exponential growth in our knowledge of DNA. The history of the DNA can be traced back to multiple devoted scientist. This article attempts to summarize, and review the basic history of DNA while providing some fascinating information about it.
DNA is the book of life. It's also the book of death. In the future we'll all be read cover to cover. Here's what it's like to take the world's first top-to-bottom gene scan.
Analysis of DNA from practicals 1 and 2 using the technique of agarose gel electrophoresis and analysis of transfomed E. coli from practical 2 (part B)
This paper explores deoxyribonucleic acid (DNA) collection and its relationship to solving crimes. The collection of DNA is one of the most important steps in identifying a suspect in a crime. DNA evidence can either convict or exonerate an individual of a crime. Furthermore, the accuracy of forensic identification of evidence has the possibility of leaving biased effects on a juror (Carrell, Krauss, Liberman, Miethe, 2008). This paper examines Carrells et al’s research along with three other research articles to review how DNA is collected, the effects that is has on a juror and the pros and cons of DNA collection in the Forensic Science and Criminal Justice community.
DNA is a long curved structure, made up of pairs of four specific bases: adenine, guanine, cytosine, and thymine, is the repository of a code from which all of our cells are made. The code is made up of base pairs which look like the
A gene is made up of different sequences of DNA. That gene is translated into protein production information. A DNA molecule is formed into a spiral, or a double helix. The DNA has a backbone that looks like a railing for the spiral and it’s made up of phosphates and suger’s. Through hydrogen bonds the spiral is sealed together. A protein is like a chain that’s folded of acid’s in a specific order, only 20 amino acids exist. A function in a body may change if the message in a gene is misspelled and the protein it encodes could possibly be wrong.
How do different types of mutations in genes affect the function of an organism? The answer is a very lengthy one, however small mutations such as adding or deleting a letter in a DNA, deoxyribonucleic acid, sequence may dramatically change the health of an organism. Mutations are changes of the DNA in an organism's DNA sequence. There are three main kinds of mutations, substitution, deletion, and insertion. Substitution many times is the least fatal because only a specific letter changes so only the amino acid of the letter is affected. Deletion is when a letter is removed from a DNA sequence, this change usually affects all amino acids after. Insertion is when a letter is inserted into the DNA sequence, this change also usually affect most amino acids after the change. A codon is a sequence of three nucleotides that together form a unit of genetic code in a DNA/RNA molecule. Huntington's
ZFN’s are chimeric proteins that are bound to “a modular array of Cys2-His2 DNA-binding zinc fingers” that are in turn bound to the FokI [1]. The TALEN’s are Transcription Activator-Like Effector (TALE) proteins that are secreted by bacteria that can control the gene expression of their host cell [1]. These particular bacterial proteins were first observed in plant cells [1]. TALENs assembly is less problematic but harder to synthesize than the ZFNs [1]. They both require formulating new DNA binding proteins for each gene [1].
From cases such as OJ Simpson to Chandra Levy, DNA profiling also called DNA fingerprinting or DNA typing has played a major role in the criminal justice system. The law enforcement community uses DNA profiling to rule out or identify suspects. Unlike hair microscopy, bite mark comparisons, shoe print comparisons, and firearm tool mark analysis, DNA typing has been developed through massive scientific research and has undergone meticulous scientific evaluation (Innocence Project). DNA is a foolproof method of identifying a perpetrator of a crime.
DNA is a term that has been used in science as well as in many parts of daily
Genetics is defined as the study of heredity. Heredity is controlled by genes, which aid in the development of a cellular organism’s definite characteristics. Such characteristics include sex, hair color, eye color, and countless other traits. Genes are composed of deoxyribonucleic acid, more commonly abbreviated as DNA. Deoxyribonucleic acid carries the genetic material for all cellular organisms. These molecules carry the information needed to direct many important processes that take place inside of the cell. This information is vital to the survival and health of the organism.