New Evolutionary and Structural Insights In Plasmodium Proteins

In this work, we perform a systematic analysis of evolutionary forces (i.e. mutational bias and natural selection) acting in plasmode proteomes. The main focus is to clarify the origin of low complexity strands in plasmodium proteins. For this purpose, we consider P. falciparum as the principal case of study and we take into account the other parasites as a suitable benchmark with which compare the low complexity enrichment, GC content and evolutionary pressures acting on codon bias. Using different bioinformatic tools and a new index that we call here selective pressure index, we find evidences that low complexity insertions are inserted in proteins where mutational bias acts as the primarily evolutionary force. Protein length has revealed to be an important evolutionary and fitness characteristic for proteins (Wang et al., 2004; Li,1997; Akashi, 2003; Moriyama and Powell, 1998; Pall et al. 2001). Interested, we lead a further study on protein length finding a preferential LC insertion in longer proteins, which are, in turn, less subject to natural selection. Additionally, dividing the proteins between LCPs (Low complexity containing proteins) and nLCPs (the counterpart), we observe that LCPs are significantly longer than nLCP. Overall, we find evidence that this class of proteins containing long low-complexity segments could be a signal of evolutionary and adapting path for these parasites.