Trypanosoma cruzi TcSRPK, the first protozoan member of the SRPK family, is biochemically and functionally conserved with metazoan SR protein-specific kinases.
A novel SR protein-specific kinase (SRPK) from the SRPK family was identified for the first time in a protozoan organism. The primary structure of the protein, named TcSRPK, presents a significant degree of identity with other metazoan members of the family. In vitro phosphorylation experiments showed that TcSRPK has the same substrate specificity relative to other SRPKs. TcSRPK was able to generate a mAb104-recognized phosphoepitope, a SRPK landmark. Expression of TcSRPK in different Schizosaccharomyces pombe strains lead to conserved phenotypes, indicating that TcSRPK is a functional homologue of metazoan SRPKs. In functional alternative splicing assays in vivo in HeLa cells, TcSRPK enhanced SR protein-dependent inclusion of the EDI exon of the fibronectin minigene. When tested in vitro, it inhibited splicing either on nuclear extracts or on splicing-deficient S100 extracts complemented with ASF/SF2. This inhibition was similar to that observed with human SRPK1. This work constitutes the first report of a member of this family of proteins and the existence of an SR-network in a protozoan organism. The implications in the origins and control of splicing are discussed.
Portal
Daniel
D
Facultad de Ciencias Exactas y Naturales, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, Buenos Aires, Argentina.
Lobo
Guillermo S
GS
Kadener
Sebastián
S
Prasad
Jayendra
J
Espinosa
Joaquín M
JM
Pereira
Claudio A
CA
Tang
Zhaohua
Z
Lin
Ren-Jang
RJ
Manley
James L
JL
Kornblihtt
Alberto R
AR
Flawiá
Mirtha M
MM
Torres
Héctor N
HN
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D003001:Cloning, Molecular; D017125:Genes, Protozoan; D005914:Globins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012568:Schizosaccharomyces / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014349:Trypanosoma cruzi / Q000201:enzymology* / Q000235:genetics
D000911:Antibodies, Monoclonal; D005914:Globins; D017346:Protein Serine-Threonine Kinases