High impact information on PRP16

• Every suppressor mutation maps to the region of PRP16 common to RNA-dependent ATPases [1].
• We have isolated seven alleles of PRP16 that, like the original allele prp16-1, allow splicing of introns with a mutant branch site (UACUAAC to UACUACC), by forming lariat intermediates at the mutant C nucleotide [1].
• We propose that decreasing the rate of ATP hydrolysis by Prp16 allows aberrantly formed lariat intermediates more time to proceed through the productive rather than the discard branch of this pathway [1].
• A mechanism to enhance mRNA splicing fidelity: the RNA-dependent ATPase Prp16 governs usage of a discard pathway for aberrant lariat intermediates [1].
• We propose that PRP16 is an excellent candidate for mediating one of the many ATP-requiring steps of spliceosome assembly and that accuracy of branchpoint recognition may be coupled to ATP binding and/or hydrolysis [2].

Biological context of PRP16

• PRP16, previously mapped to chromosome XI, is tightly linked to MRP-L20 [3].
• These results can account for the dominant negative growth phenotype and argue that the ATPase activity of PRP16 is essential for its role in splicing [4].
• We isolated alleles of two genes involved in splicing, PRP16 and PRP19, which impair alpha-tubulin synthesis thus preventing spindle assembly, as well as an allele of CDC7 that is defective in DNA replication [5].
• Nonfunctional Prp22 and Prp16 mutants exerted a dominant negative effect on cell growth [6].
• We have cloned the human counterpart of this protein and show that it shares pronounced sequence homology with Prp16p [7].

Anatomical context of PRP16

• We isolated by glycerol gradient sedimentation spliceosomes that were formed in yeast extracts depleted of PRP16 [8].

Associations of PRP16 with chemical compounds

• This structural rearrangement is dependent on the hydrolysis of ATP, since ATP gamma S, a competitive inhibitor of the PRP16 ATPase activity, does not promote the protection of the 3' splice site and formation of mRNA [9].

Physical interactions of PRP16

• The Isy1p component of the NineTeen complex interacts with the ATPase Prp16p to regulate the fidelity of pre-mRNA splicing [10].

Regulatory relationships of PRP16

• Recruitment of SLU7 to the spliceosome is greatly enhanced by prior addition of PRP16 [11].
• Interestingly, we find that PRP16 promotes a conformational change in the spliceosome which results in the protection of the 3' splice site against oligo-directed RNase H cleavage [9].

Other interactions of PRP16

• The predicted PRP22 protein sequence shares extensive homology with that of PRP2 and PRP16 proteins, which are also involved in nuclear pre-mRNA splicing [12].
• The Saccharomyces cerevisiae genes PRP2, PRP16, and PRP22 encode pre-mRNA splicing factors that belong to the highly conserved "DEAH" family of putative RNA helicases [13].
• The RNA-dependent ATPase, Prp16p, functions at a stage in splicing when ATP is required, whereas Prp18p functions at an ATP-independent stage [14].
• The complete sequence of an 18,002 bp segment of Saccharomyces cerevisiae chromosome XI contains the HBS1, MRP-L20 and PRP16 genes, and six new open reading frames [15].
• A genetic screen for suppressors of BS A-to-G mutants, which stall between the two steps, identified Prp8, the highly conserved spliceosomal factor. prp8 suppressors facilitate the second step for multiple intron mutants and interact functionally with first step suppressors, alleles of PRP16 and U6 snRNA [16].

Analytical, diagnostic and therapeutic context of PRP16

• Yeast pre-mRNA splicing factors SLU7 and PRP16 are required for cleavage of the 3' splice site and exon ligation in vitro [11].

References