Authors

A. Merckx; K. Le Roch; M. P. Nivez; D. Dorin; P. Alano; G. J. Gutierrez; A. R. Nebreda; D. Goldring; C. Whittle; S. Patterson; D. Chakrabarti;C. Doerig

Comments

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Abbreviated Journal Title

J. Biol. Chem.

Keywords

FUNCTIONAL-CHARACTERIZATION; CELL-CYCLE; KINASE; EXPRESSION; GENOME; SEQUENCE; ANTIGEN; CLONING; Biochemistry & Molecular Biology

Abstract

The molecular mechanisms regulating cell proliferation and development during the life cycle of malaria parasites remain to be elucidated. The peculiarities of the cell cycle organization during Plasmodium falciparum schizogony suggest that the modalities of cell cycle control in this organism may differ from those in other eukaryotes. Indeed, existing data concerning Plasmodium cell cycle regulators such as cyclin-dependent kinases reveal structural and functional properties that are divergent from those of their homologues in other systems. The work presented here lies in the context of the exploitation of the recently available P. falciparum genome sequence toward the characterization of putative cell cycle regulators. We describe the in silico identification of three open reading frames encoding proteins with maximal homology to various members of the cyclin family and demonstrate that the corresponding polypeptides are expressed in the erythrocytic stages of the infection. We present evidence that these proteins possess cyclin activity by demonstrating either their association with histone H1 kinase activity in parasite extracts or their ability to activate PfPK5, a P. falciparum cyclin-dependent kinase homologue, in vitro. Furthermore, we show that RINGO, a protein with no sequence homology to cyclins but that is nevertheless a strong activator of mammalian CDK1/2, is also a strong activator of PfPK5 in vitro. This raises the possibility that "cryptic" cell cycle regulators may be found among the 50% of the open reading frames in the P. falciparum genome that display no homology to any known proteins.

Journal Title

Journal of Biological Chemistry

Volume

278

Issue/Number

41

Publication Date

1-1-2003

Document Type

Article

Language

English

First Page

39839

Last Page

39850

WOS Identifier

WOS:000185713800070

ISSN

0021-9258

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