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P lasmodium falciparum SERA 5 plays a non‐enzymatic role in the malarial asexual blood‐stage lifecycle
Author(s) -
Stallmach Robert,
Kavishwar Manoli,
WithersMartinez Chrislaine,
Hackett Fiona,
Collins Christine R.,
Howell Steven A.,
Yeoh Sharon,
Knuepfer Ellen,
Atid Avshalom J.,
Holder Anthony A.,
Blackman Michael J.
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12941
Subject(s) - biology , plasmodium falciparum , recombinant dna , proteases , papain , enzyme , biochemistry , protease , cysteine protease , microbiology and biotechnology , gene , malaria , immunology
Summary The malaria parasite P lasmodium falciparum replicates in an intraerythrocytic parasitophorous vacuole ( PV ). The most abundant P . falciparum PV protein, called SERA 5, is essential in blood stages and possesses a papain‐like domain, prompting speculation that it functions as a proteolytic enzyme. Unusually however, SERA 5 possesses a S er residue ( S er596) at the position of the canonical catalytic C ys of papain‐like proteases, and the function of SERA 5 or whether it performs an enzymatic role is unknown. In this study, we failed to detect proteolytic activity associated with the S er596‐containing parasite‐derived or recombinant protein. However, substitution of S er596 with a C ys residue produced an active recombinant enzyme with characteristics of a cysteine protease, demonstrating that SERA 5 can bind peptides. Using targeted homologous recombination in P . falciparum , we substituted S er596 with A la with no phenotypic consequences, proving that SERA 5 does not perform an essential enzymatic role in the parasite. We could also replace an internal segment of SERA 5 with an affinity‐purification tag. In contrast, using almost identical targeting constructs, we could not truncate or C ‐terminally tag the SERA5 gene, or replace S er596 with a bulky A rg residue. Our findings show that SERA 5 plays an indispensable but non‐enzymatic role in the P . falciparum blood‐stage life cycle.