http://web.expasy.org/spotlight/ one month, one protein en-us spotlight@isb-sib.ch 2013-05-02T16:58:16+01:00 hourly 1 2000-01-01T12:00+00:00 http://web.expasy.org/spotlight/back_issues/sptlt148.shtml Humans have always sought to make life sweeter. In prehistoric times, sugar cane was already being grown for its sweetening powers, and the sugar added to beverages and food. But why do humans like what is sweet so much? This may well have evolved from our distant ancestors, as far back as those who bore little resemblance to us. In the wild, animals have to depend on colour but also taste – and its very close sister, smell – to distinguish what is edible from what is likely to be toxic. On the whole, bitter is better left alone. As things evolved, a sweet taste became a feeling that was comforting one way or another. So, slowly but surely, sweetness was added to all sorts of foods and liquids. And, today, sugar is usually part of a Westerner’s diet – whether we are aware of it or not. As a result, towards the end of the 20th century, it had become clear that sugar – or an excess of it – was proving to be harmful to the human population, and it was necessary to find ways of making life sweeter without the nasty side effects. In the early 1980s, one such sweetener was rediscovered in a South American plant, Lippia dulcis. Known as Hernandulcin, researchers have recently managed to isolate a key enzyme in its synthesis, known as (+)-epi-alpha-bisabolol synthase. 807@http://web.expasy.org/spotlight/ Article 2013-05-02T16:58:16+01:00 http://web.expasy.org/spotlight/back_issues/sptlt147.shtml There can be little worse than seeing – and feeling - your own child retreat into a world that doesn’t involve yours. Especially at a period of life when contact with a mother and a father is such a vital component of an infant’s development. And such a pleasurable one for the parents. Autism hits about one child in a thousand – although the contours of the affliction remain a little hazy. There are many forms. Some more serious than others. Some widespread while others are rare, or even unique. The common denominator is what could be described as a characteristic aloneness, where those suffering from autism are unable to interact socially and communicate in the way most of us do. Today, researchers believe that autism has a strong genetic component and that certain mutations are at the heart of autistic behaviour. One such mutation affects an enzyme known as BCKDK and may well be responsible for a rare hereditary form of autism that could be treated with a specific diet. 806@http://web.expasy.org/spotlight/ Article 2013-03-27T16:53:31+01:00 http://web.expasy.org/spotlight/back_issues/sptlt146.shtml We all need guidance in life. And sperm cells are no exception to the rule. In plants, as in all living beings that depend on sex to multiply, a male gamete has to reach a female gamete in order to fuse with it. All sorts of mechanisms are used for this to occur. And plants are among the most imaginative organisms on the planet, simply because their mobility is so reduced. As such, they depend on forms of mobility that surround them: wind, bees, wild animals… And they have exploited this remarkably. At the molecular level, however, plants are far more mobile. An example is pollen tube elongation. In mouse-ear cress (Arabidopsis thaliana), for instance, once the pollen is ready to germinate, a bulge protrudes from its surface, elongates – and forms what is known as the pollen tube. Hordes of molecules are involved in pollen tube elongation. But you also need something which can actually guide the tube towards the ovule. And its name is protein HAPLESS 2, or HAP2. 805@http://web.expasy.org/spotlight/ Article 2013-01-25T12:16:58+01:00 http://web.expasy.org/spotlight/back_issues/sptlt145.shtml Sex for procreation. It doesn’t sound in the least bit eccentric. But how about sex between a flower and an insect? We all know that flowers depend very much on insects to perpetuate their species. It is their answer to a lack of legs or wings. Consequently, over the millennia, plants have devised the most creative ways of luring insects into the places where they keep pollen. Some flowers have thought up shapes that resemble an insect’s mate, or places that are ideal for shelter, or they cunningly display colours that are hard for the six-legged species to ignore. Many plants give off scents to trick pollinators. One particular type of orchid has gone a step further and found out how to mimic the sex pheromones of some wasps. The poor wretches are tricked into thinking that the orchid is a potential sex mate and land on it to copulate. It’s a SAD story really. Indeed, SAD – otherwise known as stearoly-acyl carrier protein desaturase – is the key enzyme in the synthesis of the fraudulent pheromone. 804@http://web.expasy.org/spotlight/ Article 2012-12-21T10:23:21+01:00 http://web.expasy.org/spotlight/back_issues/sptlt144.shtml One thousand, every heartbeat. That is the rate at which sperm multiply in a healthy human male individual the moment puberty kicks off. It is a lot. And each sperm is potentially fertile. Ejaculation is therefore a very serious affair, and pushes one lonely egg into dangerous terrain if pregnancy is not desired. This is where contraceptives come in. Contraceptives for men – other than condoms and vasectomy – remain a tricky affair for a number of reasons. One being the sheer amount of sperm a contraceptive has to consider. Finding a solution at the level of the egg seems – naturally – less of a hassle than looking for something able to deal with millions of sperm at a time. Which is no doubt one of the reasons – though by far not the sole reason – that the popular pill came crashing into our society in the 1960s. Fifty years later, there is hope that a male contraceptive has been found. It all has to do with a protein known as Bromodomain testis-specific protein and a small inhibitor molecule known as JQ1. 803@http://web.expasy.org/spotlight/ Article 2012-11-29T16:46:24+01:00 http://web.expasy.org/spotlight/back_issues/sptlt143.shtml Humans are unique. Whichever way you look at it. We can talk. We can write. We can build skyscrapers, make art, design weapons and be a general nuisance to many other life forms. About 2.5 million years ago however, our ancestors could not. So what happened? Something was needed to modify brain structure and spark off another form of intelligence. Genetic mutations are the answer to this. And natural selection of course. There is a gene, known as SRGAP2, which is found in the brain tissues of humans and our closest relatives – chimpanzees, gorillas and orang-utans. It so happens that SRGAP2 has a duplicate – SRGAP2C – which seems to be only found in humans. SRGAP2C is thought to have appeared at about the time the Homo genus emerged from the ancestral Australopithecus genus, about 2.5 million years ago. This would suggest that SRGAP2C had a pivotal role in forging the human brain, and was engaged in shifting our ancestors’ somewhat rudimentary behaviour to more sophisticated ways. 802@http://web.expasy.org/spotlight/ Article 2012-10-30T16:44:34+01:00 http://web.expasy.org/spotlight/back_issues/sptlt142.shtml Nothing is perfect. And nature is no exception. This said, we should be grateful for nature’s imperfections because, were it not for them, we would not be here. Without the changes that have been accumulating in genes over millions of years, we would not know the rich diversity of species that inhabit Earth today. Yet we all know that mutations can be lethal to an individual. Tinker with a crucial position in a gene and you can find yourself with a severe handicap. Extensive damage to a cell’s genome can lead to all sorts of ailments, not the least cancer. This is why Nature imagined DNA repair mechanisms so as to limit the damage and prevent as many mutations as possible. One such mechanism is nucleotide excision repair, and at its heart: protein Xeroderma Pigmentosum A (XPA). 801@http://web.expasy.org/spotlight/ Article 2012-09-27T15:10:12+01:00 http://web.expasy.org/spotlight/back_issues/sptlt141.shtml There is only one way of propagating the species, and that is by mating. However, for many animals, mating usually implies hordes of sperm all fighting to get their nucleus into one egg. The same goes for humans. It is perhaps an odd thing in the first place for Nature to have devised what seems to be an uneconomical procedure, and if an oocyte is fertilised by more than one spermatozoon, the ensuing zygote is not viable. So it was necessary to develop some modus operandi by which one sperm is allowed in, while the others are kept out. In fact, over time, animals have armed themselves with more than one strategy to avoid polyspermy. One of the most definitive is to act upon the zone which surrounds an oocyte – the zona pellucida – by making it impenetrable the moment one sperm has wriggled its way through it. Scientists have known for many years that this particular region changes its structure following fertilisation but they didn’t know what caused the change. Until they discovered a protease, which has been dubbed ovastacin. 800@http://web.expasy.org/spotlight/ Article 2012-09-05T16:14:18+01:00 http://web.expasy.org/spotlight/back_issues/sptlt140.shtml Pain is a persuasive way of keeping the enemy at bay. Hosts of living beings make use of it, both in the animal and the plant world. Many of us have experienced the sting of a nettle, or indeed a wasp, a cat’s scratch and perhaps even the nip of a spider. And who hasn’t used the end of their foot to assign a kick or two, right where it hurts? Besides spitting out a few venomous words… Not many of us, however, have actually come across a snake and the twang of its venom. As we all know – or have been told – a snake’s bite can vary from being a little uncomfortable to excruciatingly painful and even harmful, not to mention fatal. Over the millennia, a snake’s venom has been perfected and become a highly specialised cocktail of hundreds, even thousands, of molecules – most of which are proteins. Recently, scientists discovered a neurotoxin – dubbed MitTx – that causes pain via acid-sensing ion channels which run along the membranes of neurons. A novelty in the world of nociception. 798@http://web.expasy.org/spotlight/ Article 2012-07-25T17:06:56+01:00 http://web.expasy.org/spotlight/back_issues/sptlt139.shtml We all need sleep. Yet sleep spells ‘off our guards’ and, from a purely biological point of view, it is not a wise move. In the land of Nod, an organism is vulnerable and an easy prey for predator. So there must be something essential in taking a nap for Mother Nature to have thought it up. Indeed, when asleep, organisms are shut off from their surroundings for a period – a period they use to build up the energy they spend their time depleting when awake. It is all a question of vital energy balance. For such a system to work, however, we need something that not only measures our body’s level of energy but also has a role in our sleeping behaviour. There happen to be many known systems that do one or the other but it is the first time that scientists have found a protein that reacts to levels of ATP and is directly involved in the length of time we sleep. 797@http://web.expasy.org/spotlight/ Article 2012-06-28T18:25:46+01:00 http://web.expasy.org/spotlight/back_issues/sptlt138.shtml Pleasure is not a human invention. Experiences that arouse a feeling of contentment are as old as life. They have, in fact, kept life going. It is yet another of Mother Nature’s tricks. If an organism perceives something as good, then it will do it again. If you want to keep a species going, the best way to do it is to reproduce. And, if the act of copulation is a pleasant experience, there’s a fair chance you’ll have another go at it. Eating, sex and social interactions are examples of acts most animals are accustomed to, and for which they are rewarded with a positive feeling. They also happen to be interactions which keep a species alive. But what happens when an animal meets frustration? Following rejection by a potential mate, for example? It finds some other way to quench its desires. Given the chance, Drosophila melanogaster will actually turn to alcohol if mating has been denied. Sex and alcohol are part of a highly complex reward system that has had plenty of time to evolve. Recently, scientists discovered the agent which orchestrates both behaviours: Neuropeptide F. 796@http://web.expasy.org/spotlight/ Article 2012-05-30T18:24:53+01:00 http://web.expasy.org/spotlight/back_issues/sptlt137.shtml We all take Spring for granted. The moment the first bouts of warmth hit the air, we fully expect to see the lawn duly mottled with daisies, leaves pushing their way into the nascent season and flowers blossoming wherever we care to look. And quite rightly so. We all know it’s going to happen since it does every year. And we do realise that Nature needs to renew itself every once in a while. The process is – you could say – automatic. But it is only automatic because there are hordes of molecules that are able to recognise, in many different ways, the environmental cues – such as warmth and humidity for instance – and translate them into growth. An amazing state of affairs, if you give it a little thought. One such molecule, known as DELLA protein RGL2, has been the centre of attention amongst plant molecular biologists for some time now. Indeed, RGL2 is proving to be at the very heart of seed germination. 795@http://web.expasy.org/spotlight/ Article 2012-04-30T14:40:29+01:00 http://web.expasy.org/spotlight/back_issues/sptlt136.shtml Fingertips are hugely sensitive. And, besides the fairly recent mobile phones that rely on them entirely, we put their sensitivity to use constantly. They are able to grasp subtle differences in temperature and texture – such as discern warm from tepid for example, or a dry surface from a greasy one. They are also able to touch or feel extremely delicately. In truth, the ends of our fingers are able to give a pretty clear picture of what is happening around us. This, of course, is thanks to nerve ends which reach the very tips of them. But scientists are now suggesting that our digital refinement may also be partly due to the epidermal ridges which cover them. In other words: our fingerprints. Fingerprint architecture is slowly being uncovered, thanks to diseases that have the power to wipe them away. One such disease – known as adermatoglyphia – is caused by a deficiency in a protein known as SMARCAD1. 792@http://web.expasy.org/spotlight/ Article 2012-03-13T10:46:04+01:00 http://web.expasy.org/spotlight/back_issues/sptlt135.shtml Someone once told me that they had spread grease all over the drainpipe that crawled up the front of their house, to prevent cats from climbing up it. It’s a very simple and pretty harmless way of keeping the enemy away. It’s hardly surprising, then, that Nature thought up just the same trick millions of years ago. Many higher plants’ stems – and also sometimes their leaves – are covered with a whitish surface, which is slightly greasy to the touch. Botanists have known for a long time that wax in plants has many roles and that the powdery blooms on stems seem to be involved in keeping harmful insects away. The question is: how? But perhaps even just as important a question is: what makes the wax? Because if scientists are able to be on a more intimate level with what produces it, then they will be able to think up insect repellents that are more in keeping with Nature’s ways. Not so long ago, researchers discovered an enzyme which synthesises lupeol, the wax component which forms the greater part of the powdery bloom. 791@http://web.expasy.org/spotlight/ Article 2012-01-31T10:59:45+01:00 http://web.expasy.org/spotlight/back_issues/sptlt134.shtml I would hate to leave the house without the odd necklace hanging round my neck. But I happen to be fortunate. Millions of other people are not. That is because a lot of jewellery contains the silvery-white metal known as nickel, which can cause disagreeable skin conditions. If nickel were confined to jewellery, things would not be so bad but it is also frequently found in zips, coins and mobile telephones for instance. And who, in our society, can easily dispense with any one of these items? 65 million people in Europe suffer from nickel allergy; that is a large part of the population. Nickel ions are able to creep off a necklace or a coin – following sweat or rubbing for example – and sink through the first layers of skin where they will trigger off an immune response resulting in dermatitis. But why does it happen in some people and not in others? The answer seems to reside in a very small region of a protein known as the toll-like receptor 4, or TLR4, which has been shown to be at the heart of nickel allergy. 790@http://web.expasy.org/spotlight/ Article 2011-12-23T11:50:01+01:00