RNA polymerase III recognizes and pauses at its terminator, an oligo(dT) tract 
in non-template DNA, terminates 3' oligo(rU) synthesis within this sequence, and 
releases the RNA. The pol III subunit Rpc11p (C11) mediates RNA 3'-5' cleavage 
in the catalytic center of pol III during pausing. The amino and carboxyl 
regions of C11 are homologous to domains of the pol II subunit Rpb9p, and the 
pol II elongation and RNA cleavage factor, TFIIS, respectively. We isolated C11 
mutants from Schizosaccharomyces pombe that cause pol III to readthrough 
terminators in vivo. Mutant RNA confirmed the presence of terminator readthrough 
transcripts. A predominant mutation site, F32, resides in the C11 Rpb9-like 
domain. Another mutagenic approach confirmed the F32 mutation and also isolated 
I34 and Y30 mutants. Modeling Y30, F32 and I34 of C11 in available cryoEM pol 
III structures predicts a hydrophobic patch that may interface with C53/37. 
Another termination mutant, Rpc2-T455I, appears to reside internally, near the 
RNA-DNA hybrid. We show that the Rpb9 and TFIIS homologous mutants of C11 
reflect distinct activities, that differentially affect terminator recognition 
and RNA 3' cleavage. We propose that these C11 domains integrate action at the 
upper jaw and center of pol III during termination.