Characterization of the autoantigen La (SS-B) as a dsRNA unwinding enzyme.
During the analysis of the La (SS-B) autoantigen for catalytic activities an ATP-dependent double-stranded RNA unwinding activity was detected. Both native and recombinant La proteins from different species displayed this activity, which could be inhibited by monospecific anti-La antibodies. La protein was able to melt dsRNA substrates with either two 3'-overhangs or a single 3'- and a 5'-overhang. Double-stranded RNAs with two 5'-overhangs were not unwound, indicating that at least one 3'-overhang is required for unwinding. Sequence elements of the La protein that might be involved in dsRNA unwinding, such as an evolutionarily conserved putative ATP-binding motif and an element that is homologous to the double-stranded RNA binding protein kinase PKR, are discussed.
Hühn
P
P
Institut für Physiologische Chemie, Johannes-Gutenberg Universität, Duesbergweg 6, D-55099 Mainz, Germany.
Pruijn
G J
GJ
van Venrooij
W J
WJ
Bachmann
M
M
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D001324:Autoantigens / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression / Q000235:genetics; D006801:Humans; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D051379:Mice; D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D012330:RNA, Double-Stranded / Q000737:chemistry* / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D012261:Ribonucleoproteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D013379:Substrate Specificity; D000097585:SS-B Antigen
D000255:Adenosine Triphosphate; D000906:Antibodies; D001324:Autoantigens; D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases; D012330:RNA, Double-Stranded; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D000097585:SS-B Antigen