U small nuclear ribonucleoprotein requirements for nematode cis- and trans-splicing in vitro.
In nematodes, a fraction of mRNAs acquires a common 22-nucleotide 5'-terminal spliced leader sequence via a trans-splicing reaction. The same premessenger RNAs which receive the spliced leader are also processed by conventional cis-splicing. Whole cell extracts prepared from synchronous embryos of the parasitic nematode Ascaris lumbricoides catalyze both cis- and trans-splicing. We have used this cell-free system and oligodeoxynucleotide directed RNase H digestion to assess the U small nuclear RNA requirements for nematode cis- and trans-splicing. These experiments indicated that both cis- and trans-splicing require intact U2 and U4/U6 small nuclear ribonucleoproteins (snRNPs). However, whereas cis-splicing displays the expected requirement for an intact U1 snRNP, trans-splicing is unaffected when approximately 90% of U1 snRNP is degraded. These results suggest that 5' splice site identification differs in nematode cis- and trans-splicing.
Hannon
G J
GJ
Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4960.
Maroney
P A
PA
Nilsen
T W
TW
D000818:Animals; D001200:Ascaris; D001483:Base Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D008969:Molecular Sequence Data; D012326:RNA Splicing; D012342:RNA, Small Nuclear / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear
D012342:RNA, Small Nuclear; D012261:Ribonucleoproteins; D017411:Ribonucleoproteins, Small Nuclear