title: Cryptosporidium parvum has an active hypusine biosynthesis pathway.
abstract: The protozoan parasite Cryptosporidium parvum causes severe enteric infection and diarrheal disease with substantial morbidity and mortality in untreated AIDS patients and children in developing or resource-limited countries. No fully effective treatment is available. Hypusination of eIF5A is an important post-translational modification essential for cell proliferation. This modification occurs in a two step process catalyzed by deoxyhypusine synthase (DHS) followed by deoxyhypusine hydroxylase. An ORF of 1086bp was identified in the C. parvum (Cp) genome which encodes for a putative polypeptide of 362 amino acids. The recombinant CpDHS protein was purified to homogeneity and used to probe the enzyme's mechanism, structure, and inhibition profile in a series of kinetic experiments. Sequence analysis and structural modeling of CpDHS were performed to probe differences with respect to the DHS of other species. Unlike Leishmania, Trypanosomes and Entamoeba, Cryptosporidium contains only a single gene for DHS. Phylogenetic analysis shows that CpDHS is more closely related to apicomplexan DHS than kinetoplastid DHS. Important residues that are essential for the functioning of the enzyme including NAD(+) binding residues, spermidine binding residues and the active site lysine are conserved between CpDHS and human DHS. N(1)-guanyl-1,7-diaminoheptane (GC7), a potent inhibitor of DHS caused an effective inhibition of infection and growth of C. parvum in HCT-8 cells.
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
authors.forename: Nimisha
authors.initials: N
authors.lastname: Mittal
authors.affiliation: Haskins Laboratories, and the Department of Chemistry and Physical Sciences, Pace University, USA.
authors.forename: Marie
authors.initials: M
authors.lastname: Morada
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Tripathi
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
authors.forename: V S
authors.initials: VS
authors.lastname: Gowri
authors.affiliation: Oral and Pharyngeal Cancer Branch, NIDCR, National Institute of Health, Bethesda, MD 20892-4340, USA.
authors.forename: Swati
authors.initials: S
authors.lastname: Mandal
authors.affiliation: Haskins Laboratories, and the Department of Chemistry and Physical Sciences, Pace University, USA.
authors.forename: Alison
authors.initials: A
authors.lastname: Quirch
authors.affiliation: Oral and Pharyngeal Cancer Branch, NIDCR, National Institute of Health, Bethesda, MD 20892-4340, USA.
authors.forename: Myung Hee
authors.initials: MH
authors.lastname: Park
authors.affiliation: Haskins Laboratories, and the Department of Chemistry and Physical Sciences, Pace University, USA.
authors.forename: Nigel
authors.initials: N
authors.lastname: Yarlett
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India. Electronic address: madhubala@mail.jnu.ac.in.
authors.forename: Rentala
authors.initials: R
authors.lastname: Madhubala
mesh_terms: D053898:Biosynthetic Pathways; D003457:Cryptosporidiosis / Q000469:parasitology*; D016785:Cryptosporidium parvum / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives* / Q000096:biosynthesis; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D015800:Protozoan Proteins; C100028:hypusine; D008239:Lysine
keywords: Cryptosporidium parvum; Deoxyhypsuine synthase; Hypusine pathway; Protozoan parasite