title: A functional core of the mitochondrial genome maintenance protein Mgm101p in Saccharomyces cerevisiae determined with a temperature-conditional allele.
abstract: Analysis of Mgm101p isolated from mitochondria shows that the mature protein of 27.6 kDa lacks 22 amino acids from the N-terminus. This mitochondrial targeting sequence has been incorporated in the design of oligonucleotides used to determine a functional core of Mgm101p. Progressive deletions, although retaining the targeting sequence, reveal that 76 N-terminal and six C-terminal amino acids of Mgm101p can be removed without altering the ability to complement an mgm101-1(ts) temperature-sensitive mutant. However, this active core is unable to complement mgm101 null mutants, suggesting that the Mgm101p might need to form a dimer or multimer to be functional in vivo. The active core, enriched in basic residues, contains 165 amino acids with a pI of 9.2. Alignment with 22 Mgm101p sequences from other lower eukaryotes shows that a number of amino acids are highly conserved in this region. Random mutagenesis confirms that certain critical amino acids required for function are invariant across the 23 proteins. Searches in the PFAM database revealed a low level of structural similarity between the active core and the Rad52 protein family.
authors.affiliation: Molecular Genetics and Evolution Group, Research School of Biological Sciences, The Australian National University, Canberra, ACT, Australia. xiaoming.zuo@utsouthwestern.edu
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Zuo
authors.forename: Donghua
authors.initials: D
authors.lastname: Xue
authors.forename: Nan
authors.initials: N
authors.lastname: Li
authors.forename: George Desmond
authors.initials: GD
authors.lastname: Clark-Walker
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D004268:DNA-Binding Proteins; D019281:Dimerization; D015966:Gene Expression Regulation, Fungal; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009687:Nuclear Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017354:Point Mutation; D021382:Protein Sorting Signals; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013696:Temperature
chemical_list: D004268:DNA-Binding Proteins; C082519:MGM101 protein, S cerevisiae; D024101:Mitochondrial Proteins; D009687:Nuclear Proteins; D021382:Protein Sorting Signals; D029701:Saccharomyces cerevisiae Proteins