Cytosine-block telomeric type DNA-binding activity of hnRNP proteins from human cell lines.
Following the observation of the presence in mammalian nuclear extracts of a DNA binding activity quite specific for the single-stranded C-rich telomeric motif, we have isolated from the K562 human cell line by affinity chromatography and identified by mass spectrometry a number of proteins able to bind to this sequence. All of them belong to different heterogeneous nuclear ribonucleoprotein subgroups (hnRNP). Whereas many of them, namely hnRNP K, two isoforms of hnRNP I, and the factor JKTBP, appear to bind to this sequence with limited specificity after isolation, an isoform of hnRNP D (alias AUF1) and particularly hnRNP E1 (alias PCBP-1) show a remarkable specificity for the (CCCTAA)n repeated motif. Both have been obtained also as recombinant proteins expressed in Escherichia coli and have been shown to retain their binding specificity toward the C-block repeated sequence. In the light of the current knowledge about these proteins, their possible involvement in telomere functioning is discussed.
Bandiera
Antonella
A
Department of Biochemistry, Biophysics, and Macromolecular Chemistry, University of Trieste, via L. Giorgieri 1, 34127, Trieste, Italy.
Tell
Gianluca
G
Marsich
Eleonora
E
Scaloni
Andrea
A
Pocsfalvi
Gabriella
G
Akintunde Akindahunsi
A
A
Cesaratto
Laura
L
Manzini
Giorgio
G
D001483:Base Sequence; D001665:Binding Sites; D003596:Cytosine / Q000737:chemistry; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D / Q000378:metabolism; D034641:Heterogeneous-Nuclear Ribonucleoprotein K / Q000378:metabolism; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D020014:K562 Cells; D020033:Protein Isoforms / Q000302:isolation & purification / Q000378:metabolism; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D012261:Ribonucleoproteins / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity; D016615:Telomere / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C000630986:HNRNPD protein, human; C111986:HNRPDL protein, human; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; D034641:Heterogeneous-Nuclear Ribonucleoprotein K; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D020033:Protein Isoforms; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D003596:Cytosine