A Key Role for Plasmodium Subtilisin-like SUB1 Protease in Egress of Malaria Parasites from Host Hepatocytes

Lina Tawk,Céline Lacroix,Pascale Gueirard,Robyn Kent,Olivier Gorgette,Sabine Thiberge,Odile Mercereau-Puijalon,Robert Ménard,Jean-Christophe Barale

doi:10.1074/jbc.m113.513234

Abstract

In their mammalian host, Plasmodium parasites have two obligatory intracellular development phases, first in hepatocytes and subsequently in erythrocytes. Both involve an orchestrated process of invasion into and egress from host cells. The Plasmodium SUB1 protease plays a dual role at the blood stage by enabling egress of the progeny merozoites from the infected erythrocyte and priming merozoites for subsequent erythrocyte invasion. Here, using conditional mutagenesis in P. berghei, we show that SUB1 plays an essential role at the hepatic stage. Stage-specific sub1 invalidation during prehepatocytic development showed that SUB1-deficient parasites failed to rupture the parasitophorous vacuole membrane and to egress from hepatocytes. Furthermore, mechanically released parasites were not adequately primed and failed to establish a blood stage infection in vivo. The critical involvement of SUB1 in both pre-erythrocytic and erythrocytic developmental phases qualifies SUB1 as an attractive multistage target for prophylactic and therapeutic anti-Plasmodium intervention strategies.

Highlights

The subtilisin-like SUB1 is involved in Plasmodium egress from erythrocytes
We show that SUB1 is expressed by hepatic merozoites, and, by generating sub1-null liver stages using FLP/flippase recognition target (FRT)-mediated conditional mutagenesis in P. berghei [27, 28], we show that SUB1-deficient hepatic merozoites are unable to egress from infected hepatocytes and to establish a blood infection
Using genetically modified SUB1-deficient parasites, we show that SUB1 plays a central role during both the pre-erythrocytic and erythrocytic phases of Plasmodium life cycle, being critically involved in merozoite egress from host hepatocytes and in the establishment of a subsequent intraerythrocytic cycle

Summary

Background

The subtilisin-like SUB1 is involved in Plasmodium egress from erythrocytes. Results: Using conditional mutagenesis, we show that SUB1 plays an essential role during Plasmodium hepatic stages. We show that SUB1 is expressed by hepatic merozoites, and, by generating sub1-null liver stages using FLP/flippase recognition target (FRT)-mediated conditional mutagenesis in P. berghei [27, 28], we show that SUB1-deficient hepatic merozoites are unable to egress from infected hepatocytes and to establish a blood infection Together, these data show that SUB1 plays a key role during the last phase of Plasmodium biological development into host hepatocytes, qualifying this enzyme as an attractive target of intervention strategies aiming at preventing as well as curing infection in humans

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION