Basic work on E. coli identifies two new keys to regulation of bacterial gene expressionJune 19, 2006MADISON—The cellular process of transcription, in which the enzyme RNA polymerase constructs chains of RNA from information contained in DNA, depends upon previously underappreciated sections of both the DNA promoter region and RNA polymerase, according to work done with the bacterium E. coli and published today (June 16) in the journal Cell by a team of bacteriologists from the University of Wisconsin-Madison. This fundamental research about a key step in RNA synthesis has important implications for the study of gene expression in other organisms, and adds to the wealth of knowledge about E. coli contributed by scientists from the UW-Madison. "The kinds of processes that we study in E. coli happen in a wide variety of bacteria of medical, environmental and agricultural importance," notes Rick Gourse, a professor of bacteriology who published the Cell paper along with a team from his lab. "This knowledge can ultimately be put to use in systems that aren't so amenable to investigation, such as bacteria that cause cholera, produce anthrax toxin or lead to ulcers and stomach cancer."
Scientists use model organisms because they are relatively easy to work with and because there is a vast amount of previous knowledge about them. They can then test whether their findings in model organisms hold true in other species, says Gourse, who studies a strain of E. coli that while harmless, is closely related to disease-causing varieties like E. coli 0157:H7. "Basic research in E. coli is very important," says Gourse. "Much of what we know about gene expression both in bacteria and in higher life forms comes from work performed originally on this model organism." The strain that Gourse works with is one of the most well-studied species in biology and has important ties to the UW-Madison. In his most recent study, Gourse investigated the interaction between RNA polymerase and promoters from the E. coli chromosome. RNA polymerase reads the information in DNA and transcribes it into chains of RNA, which are later translated into proteins. Promoter regions are specific sequences within the DNA chain that tell RNA polymerase when and where to begin transcription, and how much product to make from specific genes. Gourse's group found that there is a specific region within DNA promoters that makes contact with a highly conserved but previously underappreciated segment of the sigma subunit of RNA polymerase. While the contact with sigma is very strong at promoters for most genes, it is particularly weak at promoters that make ribosomal RNA, which means that other factors like nutritional and environmental signals ultimately regulate the expression of those genes. "In this case, regulation is achieved not because the promoter makes a special contact, but because it can't establish contact at all," says Gourse. "This is an example of how sometimes less is more, and a probably very ancient example of one of the methods that arose through evolution to regulate gene expression." Ribosomal RNA makes up the bulk of ribosomes, the molecular machines that make proteins and are present in huge numbers in all cells. Since so much of the cell's energy is used to make ribosomes, control of ribosomal RNA transcription is particularly crucial to a cell's well-being. "This work is basic to the growth of all bacteria," says Gourse. "By understanding transcription and control of ribosome synthesis in E. coli, we can understand more about these processes in bacterial species that we need to control, like those that cause disease or make toxins. E. coli is also the workhorse of the biotechnology industry. Understanding E. coli gene expression in detail allows us to harness these cells for producing products of biotechnological importance, like pharmaceuticals." Gourse's work was supported by the National Institutes of Health, the United States Department of Agriculture, and by Pfizer Biotechnology. His team included graduate student Shanil Haugen; undergraduate Christopher Ward; and senior scientists Wilma Ross and Tamas Gaal. University of Wisconsin-Madison | |||||||||||||||||||||
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Related E Coli Current Events and E Coli News Articles UT Southwestern: Killing bacteria isn't enough to restore immune function after infection A bacterial molecule that initially signals to animals that they have been invaded must be wiped out by a special enzyme before an infected animal can regain full health, researchers at UT Southwestern Medical Center have found. Researchers uncover molecule that keeps pathogens like salmonella in check Scientists at UT Southwestern Medical Center have found a potential new way to stop the bacteria that cause gastroenteritis, tularemia and severe diarrhea from making people sick. GIANT-Coli: A novel method to quicken discovery of gene function Think researchers know all there is to know about Escherichia coli, commonly known as E. coli? Think again. "E. coli has more than four thousand genes, and the functions of one-fourth of these remain unknown," says Dr. Deborah Siegele, a biology professor at Texas A&M University whose laboratory specializes in carrying out research using the bacterium. Sesame seed extract and konjac gum may help ward off Salmonella and E. coli A new study in SCI's Journal of the Science of Food and Agriculture shows that konjac gum and sesame seed extract may offer protection against different strains of E. coli and Salmonella bacteria. Researchers Identify Biofilms That Cause Infection Understanding the way bacterial cells "talk" to each other could lead to more effective methods for fighting the often persistent and serious infections caused by the biofilms they form, says a Texas A&M University professor of chemical engineering who not only has deciphered their language but also discovered how to quell their conversation. An ancient protein balances gene activity and silences foreign DNA in bacteria Compared to humans, bacteria have a much tidier genome. The tiny microorganisms pack their genes closely together, and don't carry around a lot of extraneous DNA, so-called junk DNA that fills in the gaps between genes. The Not-So-Digital Future of Digital Signal Processing Fungi processing audio signals. E. Coli storing images. DNA acting as logic circuits. It's possible, and in some cases, it's already happened. In any event, performing digital signal processing using organic and chemical materials without electrical currents could be the wave of the future. Researchers collaborate to find new vaccine technology decreases E. coli in beef cattle Despite millions of dollars spent on food safety research over the last 10 years, ground beef recalls due to E. coli O157:H7 were higher in 2007 than in 2006, according to researchers from Kansas State University and West Texas A&M University. E. coli O157:H7 has been linked to foodborne illnesses in humans after consuming contaminated beef and produce. Dissecting the genetic components of adaptation of E. coli to the mouse gut New insights into the evolutionary mechanisms that facilitate the remarkably fast adaptation of intestinal bacteria within their natural environment are provided in the January issue of PLoS Genetics by researchers from INSERM and INRA at University Paris Descartes. Poultry workers at increased risk of carrying antibiotic-resistant E. coli Poultry workers in the United States are 32 times more likely to carry E. coli bacteria resistant to the commonly used antibiotic, gentamicin, than others outside the poultry industry, according to a recent study conducted by researchers at the Johns Hopkins Bloomberg School of Public Health. More E Coli Current Events and E Coli News Articles |
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