Studies on cytochrome c methylation in yeast.

Cytochrome c-specific methylase from wheat germ

“…Aminex A-5 Chromatography. Chymotryptic digests of enzymatically methylated apocytochrome c were chromatographed on an Aminex A-5 column (0.9 X 60 cm) equilibrated with 0.2 M pyridine acetate buffer (pH 3.1) in a way similar to the previously described procedure (DiMaria et al, 1979).…”

“…Much work has been done in seeking to understand the nature and function of cytochrome c methylation, particularly in fungal organisms. The methylases that catalyze the reaction were purified from two fungal sources, Neurospora crassa and baker's yeast, and were found to be highly specific in regard to their exclusive recognition of cytochrome c as a substrate (Durban et al, 1978;DiMaria et al, 1979). In addition, they exhibit a further specificity in that they recognize only the residue 72 lysine as a site of methylation when horse heart cytochrome c is used as a substrate (DiMaria et al, 1979). This observation correlates well with the in vivo occurrence of trimethyllysine at exclusively the residue 72 in the cytochromes c of N. crassa and baker's yeast (DeLange et al, 1969(DeLange et al, , 1970.…”

Using Yeast to Define the Regulatory Role of Protein Lysine Methylation

“…Interestingly, Ctm1 is only found in the cytoplasm, and not in mitochondria [51]. Early reports on cytochrome c suggested that cytosolic apocytochrome c is co-translationally methylated [16,47]. Consistently, Ctm1-mediated methylation of Cyc1 has been proposed to help facilitate its import into the inter-membrane space of mitochrondria [10,46], and protein-protein interaction studies suggest that methylation of Cyc1 promotes its association with at least two factors important for its function and import into the inter-membrane space, Evr1 and Cyc3 [70].…”

Protein methylation in mitochondria

“…In yeast, cytochrome c (Cyc1p) is trimethylated at Lys-78 (precursor numbering), whereas the corresponding residue in mammals, referred to as Lys-72 (mature numbering), is unmethylated ( 98 ). The responsible enzymatic activity, cytochrome c-KMT, was partially purified from various sources and shown to mediate methylation of cytochrome c of fungal and mammalian origin ( 99 , 100 ), but it took nearly two decades until the corresponding gene, CTM1 , was identified in yeast ( 101 , 102 ). It was demonstrated that cytochrome c from the ΔCtm1 strain was completely unmethylated, and recombinant Ctm1p was shown to specifically target unmethylated cytochrome c (from mammals or ΔCtm1 yeast) in vitro ( 102 ).…”