Mutant/mutation
In the 'promoter-swap' mutant the PbPV5 promoter replaced by the promoter of PBANKA_0941300 (PbTEX88)

Protein (function)
The protein shows similarity to members of the functionally diverse lipocalin family, barrelshaped proteins capable of binding various hydrophobic ligands and protein interaction partners. The signature lipocalin fold comprises a short amino-terminal 3₁₀ helix followed by eight consecutive barrel-forming β-strands, an α-helix, and one more β-strand. In addition, PV5 harbors two predicted preceding amino-terminal β-strands specific to Plasmodium, as well as a signal peptide. Multiple sequence alignments with lipocalins from phylogenetically distant organisms showed the presence of a highly conserved glycine and two aromatic residues within the structurally conserved region 1 (SCR1) of PV5

Phenotype
From the paper: 'Our previous attempts to disrupt the genomic PbPV5 locus resulted only in atypical integration of the targeting construct without perturbing the endogenous gene, which is indicative of essential functions during the asexual blood-stage cycle in vivo. As an alternative genetic strategy to analyze PbPV5 function, we sought to deregulate PbPV5 expression by employing a promoter swap approach. Toward this aim, we generated parasites expressing the endogenous PbPV5 gene from the promoters of Plasmodium translocon of exported proteins 88 (PTEX88) or heat shock protein 101 (HSP101), respectively. Quantitative real-time PCR analysis of the mutants indicated that the knockdown efficiency was ∼60% in asynchronous blood stages. Impaired growth prevented quantification of knockdown levels in synchronized ex vivo early blood stages. Strikingly, in the schizont stage, the mutants exhibited significantly elevated PbPV5 transcript levels, corresponding to ∼3.4 (pv5::5′ ptex88) and ∼5.6-fold (pv5::5′hsp101) more than in WT schizonts, showing that the promoter swap strategy was successful in deregulating the physiological expression of PbPV5 throughout the asexual replication cycle. To investigate whether altered PbPV5 transcription results in reduced parasite fitness, we examined asexual propagation of the mutants in vivo. Growth of the promoter swap mutants was significantly impaired, with the pv5::5′ptex88 parasites growing at 80% and pv5::5′hsp101 parasites at only 54% of the WT growth rate . These results underscore the importance of correct PbPV5 expression during asexual replication of the parasite in vivo'.

Additional information
PbPV5 transcript abundance in the WT and the promoter swap mutants was measured by quantitative real-time PCR (qPCR) and normalized to Pb18S rRNA.

Evidence is presented that:
- PV5 Is Trafficked to the Parasite Digestive Compartments
- PbPV5 'promoter swap' mutants Form Less Hz

Other mutants