7. Conclusions
Cell division checkpoints and non-PEXEL protein export in Plasmodium
falciparum-infected human RBCs are the two aspects that need to be
pondered in apicomplexan cell biology. In this review, we have
summarised the uncanny nature of a parasite ribosomal stalk protein P2
which appears to translocate to the infected RBC (iRBC) surface and
seems to be involved in the regulation of parasite nuclear division at
the initial stage. P2 being a non-PEXEL protein, requires prior
oligomerization before trafficking to the iRBC surface which indicates
that for non-PEXEL protein export, oligomerization might be one of the
prerequisite steps in the cascade of molecular events of non-PEXEL
protein trafficking in iRBCs.
Functional inhibition of P2 oligomers on the iRBC surface either by
using monoclonal antibodies or by genetic knockdown resulted in the
nuclear division arrest of the parasites which possibly suggests that
the P2 oligomers might be involved as a checkpoint regulator or simply
as a gatekeeper at the initial stage of nuclear division. Oligomeric P2
on the iRBC surface appears to form a channel protein complex either
independently or in association with other parasite proteins to perform
a regulatory role during parasite nuclear division. These serendipitous
findings of the uncanny nature of P2 protein in malaria parasites offer
to explore more about non-ribosomal indefensible functions of ribosomal
proteins in apicomplexan parasites and certainly, the molecular role of
P2 oligomers in the regulation of parasite nuclear division are being
looked at towards a better fundamental understanding about cell division
checkpoints and the possibility to inhibit the function of P2 oligomers
using small molecules in iRBCs.