Davies Heledd M, Nofal Stephanie D, McLaughlin Emilia J, Osborne Andrew R
The Francis Crick Institute, London, NW1 1AT, United Kingdom.
London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, United Kingdom.
FEMS Microbiol Rev. 2017 Nov 1;41(6):923-940. doi: 10.1093/femsre/fux046.
Five species of parasite cause malaria in humans with the most severe disease caused by Plasmodium falciparum. Many of the proteins encoded in the P. falciparum genome are unusually enriched in repetitive low-complexity sequences containing a limited repertoire of amino acids. These repetitive sequences expand and contract dynamically and are among the most rapidly changing sequences in the genome. The simplest repetitive sequences consist of single amino acid repeats such as poly-asparagine tracts that are found in approximately 25% of P. falciparum proteins. More complex repeats of two or more amino acids are also common in diverse parasite protein families. There is no universal explanation for the occurrence of repetitive sequences and it is possible that many confer no function to the encoded protein and no selective advantage or disadvantage to the parasite. However, there are increasing numbers of examples where repetitive sequences are important for parasite protein function. We discuss the diverse roles of low-complexity repetitive sequences throughout the parasite life cycle, from mediating protein-protein interactions to enabling the parasite to evade the host immune system.
有五种寄生虫可导致人类患疟疾，其中恶性疟原虫引起的疾病最为严重。恶性疟原虫基因组中编码的许多蛋白质异常富含重复性低复杂性序列，这些序列所含氨基酸种类有限。这些重复序列会动态扩展和收缩，是基因组中变化最迅速的序列之一。最简单的重复序列由单个氨基酸重复组成，例如多聚天冬酰胺序列，约25%的恶性疟原虫蛋白质中都有这种序列。由两种或更多种氨基酸组成的更复杂重复序列在不同的寄生虫蛋白质家族中也很常见。对于重复序列的出现尚无普遍解释，许多重复序列可能对所编码的蛋白质没有功能，对寄生虫也没有选择性优势或劣势。然而，越来越多的例子表明，重复序列对寄生虫蛋白质功能很重要。我们讨论了低复杂性重复序列在整个寄生虫生命周期中的多种作用，从介导蛋白质-蛋白质相互作用到使寄生虫能够逃避宿主免疫系统。
