Taxonomic distribution of proteins containing AdoHcyase domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing AdoHcyase domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

Mutational and nucleotide sequence analysis of S-adenosyl-L-homocysteinehydrolase from Rhodobacter capsulatus.

Sganga MW, Aksamit RR, Cantoni GL, Bauer CE
Proc Natl Acad Sci U S A. 1992; 89: 6328-32

The genetic locus ahcY, encoding the enzyme S-adenosyl-L-homocysteinehydrolase (EC 3.3.1.1) from the bacterium Rhodobacter capsulatus, has beenmapped by mutational analysis to within a cluster of genes involved inregulating the induction and maintenance of the bacterial photosyntheticapparatus. Sequence analysis demonstrates that ahcY encodes a 51-kDapolypeptide that displays 64% sequence identity to its human homolog.Insertion mutants in ahcY lack detectable S-adenosyl-L-homocysteinehydrolase activity and, as a consequence, S-adenosyl-L-homocysteineaccumulates in the cells, resulting in a 16-fold decrease in theintracellular ratio of S-adenosyl-L-methionine toS-adenosyl-L-homocysteine as compared to wild-type cells. The ahcYdisrupted strain fails to grow in minimal medium; however, growth isrestored in minimal medium supplemented with methionine or homocysteine orin a complex medium, thereby indicating that the hydrolysis ofS-adenosyl-L-homocysteine plays a key role in the metabolism ofsulfur-containing amino acids. The ahcY mutant, when grown in supplementedmedium, synthesizes significantly reduced levels of bacteriochlorophyll,indicating that modulation of the intracellular ratio ofS-adenosyl-L-methionine to S-adenosyl-L-homocysteine may be an importantfactor in regulating bacteriochlorophyll biosynthesis.