TY - JOUR
T1 - Reversible inhibition of the second step of splicing suggests a possible role of zinc in the second step of splicing
AU - Shomron, Noam
AU - Malca, Hadar
AU - Vig, Ida
AU - Ast, Gil
N1 - Funding Information:
We would like to thank Dr Pinchuk Ilya for his assistance with the calculations in the Supplementary Material. This work was supported by an award from the Israel Academy of Science and in part by a grant from the Israel Cancer Association and the Leukemia Research Foundation to G.A. N.S. was partially supported by the Rieger Foundation scholarship.
PY - 2002/10/1
Y1 - 2002/10/1
N2 - A multicomponent complex of proteins and RNA is assembled on the newly synthesized pre-mRNA to form the spliceosome. This complex catalyzes a two-step transesterification reaction required to remove the introns and ligate the exons. To date, only six proteins have been found necessary for the second step of splicing in yeast, and their human homologs have been identified. We demonstrate that the addition of the selective chelator of zinc, 1,10-phenanthroline, to an in vitro mRNA splicing reaction causes a dose-dependent inhibition of the second step of splicing. This inhibition is accompanied by the accumulation of spliceosomes paused before completion of step two of the splicing reaction. The inhibition effect on the second step is due neither to snRNA degradation nor to direct binding to the mRNA, and is reversible by dialysis or add-back of zinc, but not of other divalent metals, at the beginning of the reaction. These findings suggest that the activity of a putative zinc-dependent metalloprotein(s) involved in the second step of splicing is affected. This study outlines a new method for specific reversible inhibition of the second step of splicing using external reagents, and suggests a possible role of divalent cations in the second step of mRNA splicing, most likely zinc.
AB - A multicomponent complex of proteins and RNA is assembled on the newly synthesized pre-mRNA to form the spliceosome. This complex catalyzes a two-step transesterification reaction required to remove the introns and ligate the exons. To date, only six proteins have been found necessary for the second step of splicing in yeast, and their human homologs have been identified. We demonstrate that the addition of the selective chelator of zinc, 1,10-phenanthroline, to an in vitro mRNA splicing reaction causes a dose-dependent inhibition of the second step of splicing. This inhibition is accompanied by the accumulation of spliceosomes paused before completion of step two of the splicing reaction. The inhibition effect on the second step is due neither to snRNA degradation nor to direct binding to the mRNA, and is reversible by dialysis or add-back of zinc, but not of other divalent metals, at the beginning of the reaction. These findings suggest that the activity of a putative zinc-dependent metalloprotein(s) involved in the second step of splicing is affected. This study outlines a new method for specific reversible inhibition of the second step of splicing using external reagents, and suggests a possible role of divalent cations in the second step of mRNA splicing, most likely zinc.
UR - http://www.scopus.com/inward/record.url?scp=0036796375&partnerID=8YFLogxK
U2 - 10.1093/nar/gkf553
DO - 10.1093/nar/gkf553
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AN - SCOPUS:0036796375
SN - 0305-1048
VL - 30
SP - 4127
EP - 4137
JO - Nucleic Acids Research
JF - Nucleic Acids Research
IS - 19
ER -