Jr. Webb et Wr. Mcmaster, MOLECULAR-CLONING AND EXPRESSION OF A LEISHMANIA-MAJOR GENE ENCODING A SINGLE-STRANDED DNA-BINDING PROTEIN CONTAINING 9 CCHC ZINC-FINGER MOTIFS, The Journal of biological chemistry, 268(19), 1993, pp. 13994-14002
The genes encoding GP63, the major surface glycoprotein of the protozo
an parasite Leishmania, are highly conserved across diverse species of
Leishmania both within the protein coding region and in the immediate
5'-untranslated region. Located between the 3' trans-spliced leader a
cceptor site and the translational initiation codon of the GP63 gene i
s an area of conserved hexanucleotide direct repeats (CTCGCC) which va
ry in number according to species. To determine whether these repeats
represent a site of protein DNA interaction, a Leishmania major lambda
gt11 expression library was screened with a radiolabeled synthetic oli
godeoxynucleotide probe containing multiple CTCGCC repeats to detect c
lones expressing functional DNA-binding proteins. Using this approach
a gene was isolated which encodes a sequence-specific DNA-binding prot
ein referred to as HEXBP (hexamer-binding protein). Sequence analysis
of the HEXBP gene showed that HEXBP contains nine cysteine-rich motifs
which are identical to a consensus sequence known as the ''CCHC type'
' zinc finger. This motif is present in a number of nucleic acid-bindi
ng proteins including the nucleocapsid protein of retroviruses. In acc
ordance with the activity exhibited by other proteins containing the '
'CCHC'' motif, HEXBP binds to single-stranded nucleic acids as demonst
rated by gel mobility shift assays and Southwestern blot assays.