Taxonomic distribution of proteins containing AdoHcyase_NAD domains

The AdoHcyase_NAD domain within your query sequence starts at position 267 and ends at position 428, and its E-value is 2.21e-103.

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.