Mutant/mutation
The mutant lacks expression of coronin.

Protein (function)
From the paper:
The motor driving this gliding motility is located underneath the plasma membrane in a narrow space delimited by a membrane organelle called the inner membrane complex (IMC) that subtends the plasma membrane at a distance of approximately 30nm. Within this space, it is thought that myosin, anchored in the IMC, drives actin filaments rearwards in what resembles retrograde flow. Actin filaments themselves are likely linked to transmembrane proteins that contain adhesive domains including an integrin-like Adomain. This linkage thus drives parasite motility upon attachment to a substrate although it is not clear how the different transmembrane proteins transmit force. Actin filaments are extremely short in Plasmodium as well as in related parasites and cannot be routinely visualized. This is at least partly due to a number of differences in the actin monomer structure that prevent the formation of long filaments. In addition, actin binding proteins might play a role in regulating actin filament dynamics.
The Plasmodium genome only encodes a small set of canonical actin-binding proteins. The only bona-fide actin filament-binding protein in the Plasmodium genome is coronin, which shares only 31% sequence identity to Dictyostelium coronin. Coronin is conserved among the different species of Plasmodium and shows 57% identity between the major human malaria-causing parasite P. falciparum and the rodent model parasite P. berghei Coronins are a family of actin filament-binding proteins with the first identified coronin described to be important for cell motility and differentiation in Dictyostelium discoidum. All coronins have one or twoWD40 repeat-containing ß-propellers that mediate actin filament-binding. Coronins can harbor 2 independent actin-binding sites in their ß-propellers and can also bind membranes. Furthermore, coronins can contain a number of additional domains and regions that allow dimer formation and interaction with a range of different proteins including actin-binding proteins and microtubules. In alveolata, a major superphylum of protists, coronins belong to the orphan class of short coronins containing one ß-propeller. Coronin has been examined in several protozoan parasites such as the human malaria-causing parasite Plasmodium falciparum, the related apicomplexan parasite Toxoplasma gondii and in Leishmania, unicellular parasites from the excavata branch. Yet the coronins in each of these organisms display divergent functions. While in Leishmania coronin is essential for microtubule organization, in Toxoplasma gondii it only binds actin filaments weakly and plays a minor, uncharacterized role during host cell invasion. In P. falciparum coronin was identified and characterized as an actin filament-binding protein and shown to be able to bind to membranes and bundle actin filaments. These functional differences might be explained by the divergence of coronin among these organisms.

Phenotype
Normal numbers of midgut sporozoites are formed. Significantly lower numbers (60-70%) of coronin(-) sporozoites accumulate in the salivary glands. Evidence is presented for a (slightly) reduced liver stage development. Coronin(-) sporozoites show aberrant motility. However, no evidence was found for a defect in migration in the skin.

Additional information
Eveidence is presented that coronin localizes to the rear of motile sporozoites in an actin dependent manner (see also mutant RMgm-1498 that expresses an mCherry-tagged coronin).
A number of mutants have been generated expressing mutated forms of coronin. Analyses of these mutants provided evidence for that coronin show distinct binding to membranes and actin filaments and that mutants with mutated coronins exhibit defects in sporozoite motility.

From the paper:
Here we generated a series of parasite lines that either lack coronin, contain mutations of important residues in the ß-propeller or express coronin fused to mCherry in P. berghei, a rodent model parasite. These lines show that P. berghei coronin localizes to the sporozoite periphery in a calcium dependent but actin independent manner and actively contributes to parasite motility through actin filament-binding. During the rapid onset of migration extracellular ligands first trigger intracellular calcium release prior to actin filament formation and coronin relocalization to the rear of the gliding sporozoite. Importantly, coronin is required for efficient transmission of the parasite from mosquitoes to mice as coronin(-) parasites and parasites expressing mutated coronin show defects in salivary gland invasion.
 
Other mutants
See the link PF3D7_1251200 for other related mutants