Human gut parasite has a sinister use for its stolen genes

It is well established knowledge that bacteria rou?nely exchange genes between unrelated species, crea?ng an extensive network of informa?on flow independent of sexual reproduc?on. By acquiring new genes, each being a blueprint for a single protein, the bacteria gain also the func?ons the proteins perform within the cell. This phenomenon is forcing itself on our aJen?on especially with the spread of an?bio?c resistance among bacteria, which is threatening our ability to fight infec?ons. But is swapping of genes important also in more complex organisms like animals, plants, or single-celled pro?sts? Their DNA might be beJer protected against change as it is enwrapped in membranes of the nucleus, but it is unclear if this barrier plays a significant role. Answers to this puzzle will have far-reaching implica?ons both for evolu?onary theories and prac?cal understanding of diseases. The jury is s?ll out, but new data from a human gut parasite add to the growing pile of evidence that free movement of genes is indeed happening across the whole tree of life. Roughly one billion people worldwide have their guts infected with a microscopic sphere-shaped pro?st called Blastocys)s which is distantly related to kelp and water molds. The parasite oSen goes unno?ced, but in some individuals, it manifests with severe diges?ve m a l f u n c ? o n s r e m i n i s c e n t o f t h e irritable bowel syndrome. A collabora?on of Canadian scien?sts has now thoroughly sequenced and assembled the complete gene?c informa?on of Blastocys)s and searched it for genes poten?ally stolen from other organisms, and iden?fied 167 genes which clearly represent recent gains. Most of these genes came from bacteria, oSen from groups coinhabi?ng guts of humans and other animals together with Blastocys)s, and about 20 originated from more advanced organisms, possibly past hosts of the parasite. Blastocys)s did not gain and retain the genes randomly. The researchers say that most of the genes they iden?fied may provide a direct advantage for the parasi?c lifestyle of Blastocys)s. Some of them are likely involved in scavenging and u?lizing nutrients which the parasite finds in the gut environment. Others may serve in evading recogni?on by the immune system or surviving its aJacks. The newly iden?fied genes may therefore be important for the parasite's pathogenesis, in other words, the mechanisms leading to disease. S?ll a lot of work has to be done before we can talk about prac?cal u?liza?on of this knowledge, but now we know the path. The genes which Blastocys)s stole and incorporated into its own arsenal may one day provide targets for newly developed drugs, becoming an Achilles' heel of the parasite. The most promising targets are the genes which are also shared with other, unrelated, parasi?c pro?sts, since these are evidently crucial for parasi?sm. By targe?ng them, the drugs can damage the parasite's interac?ons with host cells and damper its ability to invade. These genes may also be safer targets because they came from organisms even more evolu?onary distant from humans than the parasite itself, which means a lower risk of side effects for the pa?ent. Regardless of the future therapeu?c applica?ons, the study of Blastocys)s and its stolen genes has already provided decisive insights into the mechanisms of biological evolu?on. It is becoming more and more difficult to ignore the importance of gene transfer into, 1: Department of Parasitology, Faculty of Science, Charles University in Prague, Czech Republic