Protein spotlight
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「Protein Spotlight」 (ISSN 1424-4721) は、スイスバイオインフォマティクス研究所のSwiss-Protチームの月間レビューである。特定のタンパク質やタンパク質ファミリーについて、やさしく解説している。
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- another shade of red by vgerrits (2015/06/01 19:48)There is more to red than meets the eye. The colour has probably been around for as long as plants have, spreading red across stalks, leaves, fruits and flowers to seduce the incidental pollinator or ward off predators. Surprisingly, although Nature usually tends towards the most economical, in plants there are two ways of making red by using either of two biosynthetic pathways: the betalain one, or the anthocyanin one. While the anthocyanin pathway only produces reds, the betalain pathway supplies both red and yellow pigments. But anthocyanins and betalains are never synthesized within the same plant; it is one or the other. This probably has to do with evolution and the choice of favouring one pathway over another. One protein which has a key role in triggering off the betalain pathway has recently been revealed - transcription factor MYB1.
- a question of perspective by vgerrits (2015/04/09 21:01)Paradigms are meant to be broken. In the 1980s, biology students were taught "the one gene = one protein" dogma which has since stepped down from its pedestal, as we now know that one gene, by way of any number of post-translational modifications on the protein sequence, can actually give rise to more than one protein. Or what would be more correct: to more than one function. In the same way, structural biologists are beginning to realise that proteins are not always stable but that a significant amount exist in particularly unstable forms - which has given them the name "disordered proteins". Until recently, proteins were thought to fold up into thermodynamically stable forms before getting on with what they had to do. Now we know that it is not necessarily the case. Eukaryotic translation initiation factor 4E-binding protein 2, for instance, is one such disordered protein whose lack of stability gives rise to a new kind of biological regulation.
- taming genes by vgerrits (2015/03/03 20:37)Some mistakes turn out to be beneficial. And life, or its survival, has always thrived on them. Add a few mutations to a genome, drench it in time, and you have the driving force of evolution. Transposons - these bits of DNA that are able to skip along genomes - are just one kind of mutation that has contributed hugely towards life's unfolding. Not so long ago, researchers discovered remnants of a well-known transposon, made up of so-called mariner elements, glued aside another gene whose product is a histone methyltransferase. This chimeric gene, baptised SETMAR, expresses a product whose roles are similar to both of its parts. But with a little twist. A twist which, in the past 50 million years, has contributed to human evolution, and is due to the protein it expresses: histone-lysine N-methyltransferase SETMAR.
- the hidden things by vgerrits (2014/12/24 01:14)Nature has its secret ways. During the course of the 19th century, the Augustinian friar Gregor Mendel worked out the basics of genetic inheritance as he crossbred pea plants. About a century later, it has become obvious that the inheritance of a given trait is in fact not so straightforward. What is more, there seems to be growing evidence that a given trait can actually be handed down generations - even skipping generations - without it being frankly dictated by a gene; a notion which, in the realm of biological dogmas, is like a crack at the base of a sturdy building. The concept is not really new but scientists may have strengthened it following studies on folate metabolism - one of whose major protagonists is methionine synthase reductase, or Mtrr - by suggesting a mechanism of inheritance that is driven by entities which are not an actual part of a gene, otherwise known as epigenetic inheritance.
- the heart of things by vgerrits (2014/11/22 01:59)There is no life without a heart. And none without a beat. Which is why the heart is one of the first organs to be formed - albeit in a rudimentary fashion - very early on in life; as early as two weeks in the human embryo which, at that point, bears little resemblance to a human being. The heart is such a vital part of us that it has been a symbol of life for millennia, as it has of love, because so many of our emotions pass through it, either making it flutter, skip a beat or beat faster. It is so central that a lot of time, thought and energy is put into keeping a heart pulsing, be it during an operation or following cardiac arrest. Some hearts are also born lazy, which can be seriously disabling. Pacemakers are an answer to this, but they are artificial so have their drawbacks. A biological alternative, however, known as T-box transcription factor Tbx18, could prove to be revolutionary in the near future.
- moving forward by vgerrits (2014/10/01 01:11)Nature's imagination seems endless, and so is Man's. For as long as humans have existed, they have twisted Nature to meet their own needs. Wood has been used to keep them warm. Whale oil has been used to make light. Water has been harnessed to make electricity. And when the era of bio-engineering developed, it was not long before scientists found ways to tinker with an organism's genome for the benefits of mankind. Nowadays, the realm of medication depends heavily on biotechnology. And so, undoubtedly, will novel biofuels. With fossil fuels slowly trickling away, it is becoming paramount to find alternative sources of fuel. And ethanol, though not a new idea, is one. Ethanol is synthesized quite naturally by microorganisms - usually as a waste product - and is the result of the degradation of sugars, by an enzyme known as inulinase, and their subsequent fermentation.
- two's company by vgerrits (2014/08/30 20:09)Pairing up is sometimes paramount to life. On the molecular scale, dimerization in our bodies is at the heart of many fundamental biological processes, such as the transduction of signals from the outside of a cell to the inside for instance. Split two molecules apart and, just like taking the propeller away from a ship, things are sure to change drastically. Signal transduction, on which life depends, is hugely due to protein-protein interaction. A ligand recognises its receptor, binds to it, thereby triggering off biological processes downstream. In the case of Kit ligand, and its receptor Kit, their binding is subject to the dimerization of both the ligand and its receptor, following which signals are transduced further downstream triggering off other biological processes. Kit ligand and Kit are a case of substantial conformational change on the molecular level - dimerization but also angles which bring about flexibility - that are necessary for Kit to get on with its job.
- it did it its way by vgerrits (2014/07/17 19:48)Temperatures can get cold. And living organisms have to find ways of keeping themselves warm. Humans use clothes. Polar bears grow fur. Whales are lined with blubber. And many animals avoid the cold by migrating to warmer parts of the planet. But for cold-blooded animals - such as fish - things are sometimes more complicated. Especially when they live in waters which are ice-cold, on a seasonal basis or not. The formation of ice in an organism is dangerous because it can damage cells irreversibly. To solve this problem, Nature thought up an antifreeze system which hinders ice formation: antifreeze proteins. There are all sorts of antifreeze proteins but one is particularly special - Maxi - and keeps fish alive in waters as cold as - 1.9 °C. As its name suggests, it is much larger than the other antifreeze proteins known to date, but it also behaves very differently. What is more, its 3D structure has shed a very different light on the way the core of a protein is formed.
- the senses confused by vgerrits (2014/06/17 18:53)Life is made of smells. Because smells play an important part in an organism's ordinary day to day life - it's a question of survival. And who says survival, says reproduction and food. Flowers exude perfumes to attract pollinators. There is evidence that spermatozoa sniff their way to eggs. Animals avoid eating what smells bad, but will be seduced by what smells good. While others let off putrid scents to ward off predators or, on the contrary, discharge encouraging ones to lure their prey. On the whole, the process is simple. If a fragrance is pleasant, an organism will be attracted by it. If it is not, it will turn away. This relatively direct means of communication between organisms is carried out by a more or less elaborate olfactory system. Recently, scientists managed to modify an odorant receptor - known as Orco - of Aedes aegypti, the mosquito responsible for transmitting yellow fever and dengue fever to humans. In so doing, the mosquito seemed to lose its taste for human skin - a valuable fact which could be used to develop powerful insect repellents.
- an unusual chemistry by vgerrits (2014/05/20 21:16)What is new to us is not necessarily new to Nature. There are things that have been around for years, even millions of years, which have remained hidden to scientists because they lacked the knowledge to unveil them. The methane you find in oceans - a portion of which ends up in the atmosphere - is one of Nature's riddles. The methane content of the ocean is substantial and, according to researchers, cannot have only been synthesized by the anaerobic archaea who live in its depths. Especially since deep-ocean methane can take a long time to percolate from its original source to the shallower parts of the sea. So what else could be making methane in these waters? Well recently, biologists discovered that a marine microbe living closer to the surface of the ocean, and known as Nitrosopumilus maritimus, feeds on a very unusual chemical compound - HEP - and, in the process, releases methane. And, since the ocean is bulging with these microbes, this could very well account for a lot of the methane that is found in it. Shortly after this revelation, scientists discovered the enzyme that converts this particular compound, which they baptised methylphophonate synthase.
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Protein Spotlight
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