Mutant/mutation
The mutant expresses a C-terminal mCherry-tagged version of IMC1c (inner membrane complex protein 1e, putative).

Protein (function)
The three motile and invasive stages (zoites) of Plasmodium species (i.e. ookinetes, sporozoites and merozoites), as well as zoites of other apicomplexan parasites, possess a similar cortical structure termed the pellicle. The pellicle is essentially made up of the plasma membrane and an underlying double membrane structure termed the inner membrane complex (IMC). Closely associated with the IMC on its cytoplasmic side is a network of intermediate filaments termed the subpellicular network (SPN), which supports the pellicular membranes and provides mechanical strength to the cell. Several members of an Apicomplexa-specific family of proteins termed IMC1 proteins have been identified as components of the SPN. Structurally related proteins from ciliates and dinoflagellate algae have since been added to this protein family renamed ‘alveolins’, which now defines the Alveolata infrakingdom. In the genus Plasmodium, the number of members of the alveolin family has risen to 12, which are encoded by conserved and syntenic genes. The alveolin family members display differential expression between the three zoite stages of the parasite, with the largest repertoires present in the ookinete and sporozoite according to proteomic studies. It has been shown in the rodent malaria species Plasmodium berghei that the disruption of individual alveolin family members expressed in sporozoites (PbIMC1a), in ookinetes (PbIMC1b) or in both these zoites (PbIMC1h) results in morphological abnormalities that are accompanied by reduced tensile strength of the zoite stages in which they are expressed. Besides roles in morphogenesis and mechanical strength, the Plasmodium alveolins are also involved in gliding motility in both ookinetes and sporozoites, most likely through interactions with components of the glideosome that are situated within the pellicular cytoplasm.

PbIMC1c (PBANKA_120200) is composed of 278 amino acids encoded by a single exon. PbIMC1c and its orthologous. proteins share a highly conserved amino-terminal domain related to the IMCp domain superfamily (Pfam12314) that defines the IMC1 proteins/alveolins. The proteins also possess a conserved cysteine motif at the carboxyterminus similar to the cysteine motifs described in PbIMC1a and TgIMC1 that is believed to act as a palmitoylation signal.

Phenotype
Unsuccessful attempts to to knock-out imc1c (RMgm-1120) indicates an essential role of IMC1c in blood stage development/multiplication.

mCherry-tagging had no effect on the viability of all blood stages

Analyses of the mutants expressing mCherry- and GFP-tagged (RMgm-1123)  IMC1c showed:
Strong expression in blood stages that appeared cytoplasmic, except in mature schizonts where it showed clear peripheral localization in individual merozoites. Ookinetes displayed very strong fluorescence with a cortical distribution. Sporulated oocysts and sporozoites also displayed strong fluorescence, which was concentrated at the cortex of the sporozoites. These combined observations are fully consistent with a pellicular localization of PbIMC1c and are in agreement with it being a predicted SPN resident. Besides the peripheral distribution of PbIMC1c in sporozoites, a thickened area was present near one extremity (anterior) of the cell. Evidence is presented for temporal recruitment to the SPN of sporozoites.

Additional information

Other mutants
Unsuccessful attempts to to knock-out imc1c (RMgm-1120)
A mutant expressing a GFP-tagged version of IMC1c (RMgm-1123)
Click on IMC1 for other gene-deletion/tagging mutants targeting IMC1 proteins