An insertion in the methyltransferase domain of P. falciparum trimethylguanosine synthase harbors a classical nuclear localization signal.
Many Plasmodium falciparum proteins do not share homology with, and are generally longer than their respective orthologs. This, to some extent, can be attributed to insertions. Here, we studied a P. falciparum RNA hypermethylase, trimethylguanosine synthase (PfTGS1) that harbors a 76 amino acid insertion in its methyltransferase domain. Bioinformatics analysis revealed that this insertion was present in TGS1 orthologs from other Plasmodium species as well. Interestingly, a classical nuclear localization signal (NLS) was predicted in the insertions of primate parasite TGS1 proteins. To check whether these predicted NLS are functional, we developed an in vivo heterologous system using S. cerevisiae. The predicted NLS when fused to dimeric GFP were able to localize the fusion protein to the nucleus in yeast indicating that it is indeed recognized by the yeast nuclear import machinery. We further showed that the PfTGS1 NLS binds to P. falciparum importin-α in vitro, confirming that the NLS is also recognized by the P. falciparum classical nuclear import machinery. Thus, in this study we report a novel function of the insertion in PfTGS1.
Department of Biosciences & Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
Prasad H
PH
Babar
Department of Biosciences & Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
Vishakha
V
Dey
Department of Biosciences & Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
Praveen
P
Jaiswar
Department of Biosciences & Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India. Electronic address: patankar@iitb.ac.in.
Swati
S
Patankar
D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D015870:Gene Expression; D005822:Genetic Vectors; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D016254:Mutagenesis, Insertional; D019913:Nuclear Localization Signals / Q000235:genetics*; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics*; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs / Q000235:genetics*; D021381:Protein Transport
D019913:Nuclear Localization Signals; D008780:Methyltransferases; C456271:trimethylguanosine synthase
Importin-α; Insertion; Nuclear localization signal; Plasmodium falciparum; Saccharomyces cerevisiae; Trimethylguanosine synthase