Related Experiment Videos
Characterization of a unique protein component of yeast RNase MRP: an RNA-binding protein with a zinc-cluster domain
1Department of Developmental Biology, Stanford University School of Medicine, California 94305-5427.
Abstract:
RNase MRP is a ribonucleoprotein endoribonuclease that has been shown to cleave mitochondrial primer RNA sequences from a variety of sources. Most of the RNase MRP activity is found in the nucleus where it plays a role in the processing of 5.8S rRNA. A temperature-conditional point mutation in the yeast RNA component of the enzyme has been identified. This mutation results in a loss of normal rRNA processing at the nonpermissive temperature while cellular levels of the RNA component of RNase MRP remain stable. High-copy suppressor analysis of this point mutation was employed to identify interacting proteins. A unique suppressor, termed SNM1 (suppressor of nuclear mitochondrial endoribonuclease 1), was identified repeatedly. The SNM1 gene was localized to the right arm of chromosome IV, directly adjacent to the SNF1 gene, and it contains an open reading frame encoding a protein of 198 amino acids. The protein contains a leucine zipper motif, a zinc-cluster motif, and a serine/lysine-rich tail. The gene was found to be essential for viability in a yeast cell, consistent with it being a protein component of the RNase MRP ribonucleoprotein complex. Recombinant SNM1 protein binds RNA in both gel retardation and Northwestern assays. Antibodies raised against bacterially expressed proteins identified four separate species in yeast whole cell extracts. Antibodies directed against the SNM1 protein immunoprecipitated RNase MRP RNA from whole-cell extracts without precipitating the structurally and functionally related RNase P RNA. We propose that the SNM1 protein is an essential and specific component of the RNase MRP ribonucleoprotein complex, the first unique protein of this complex to be identified.
Insights
Researchers identified SNM1, a novel protein essential for yeast cell viability. SNM1 is a specific component of the RNase MRP ribonucleoprotein complex, crucial for RNA processing.
Area of Science:
- Molecular Biology
- Biochemistry
- Yeast Genetics
Background:
- RNase MRP is a ribonucleoprotein endoribonuclease involved in rRNA processing.
- A specific mutation in the RNA component of RNase MRP affects its function.
- Understanding RNase MRP complex composition is crucial for elucidating its biological roles.
Purpose of the Study:
- To identify proteins interacting with the RNase MRP complex.
- To characterize a novel suppressor of an RNase MRP mutation.
- To determine if the identified suppressor is a component of RNase MRP.
Main Methods:
- High-copy suppressor analysis in yeast.
- Gene localization and sequencing.
- Recombinant protein expression and RNA binding assays (gel retardation, Northwestern).
- Antibody generation and immunoprecipitation studies.
Main Results:
- A novel gene, SNM1, was identified as a suppressor of the RNase MRP mutation.
- SNM1 encodes an essential protein with RNA-binding capabilities.
- SNM1 protein specifically immunoprecipitates RNase MRP RNA, not RNase P RNA.
- SNM1 contains a leucine zipper and a zinc-cluster motif.
Conclusions:
- SNM1 is an essential protein component of the RNase MRP ribonucleoprotein complex.
- SNM1 is the first unique protein component identified for RNase MRP.
- The identification of SNM1 provides new insights into RNase MRP structure and function.