| Primary Identifier | IPR002708 | Type | Domain |
| Short Name | HcyBio |
| description | This presumed domain (used to be named as DUF39) is about is about 360 residues long. The function of this domain is not clear. It is found at N terminus in some proteins that have two C-terminal cystathionine beta-synthase (CBS) domains, such as MJ0100 from Methanocaldococcus jannaschii. This domain can also be found in proteins that contain two C-terminal inserted Fe4S domains []. In Methanocaldococcus jannaschii, MJ0100 (also known as MA1821) is involved in Hcy (homocysteine) biosynthesis. Its CBS domains bind S-adenosyl-l-methionine (SAM) and 5'-methylthioadenosine (MTA), which induce a conformational change consistent with regulatory function. Another protein in the homocysteine biosynthesis pathway, MA1822, is involved in the reduction of the disulfide formed in MA1821 during the conversion of Asa (aspartate semialdehyde) to Hcy [, ].The DUF39-CBS and DUF39-ferredoxin architectures repeatedly occur together in the genomes of methanogenic Archaea, suggesting they may be of diverged function. This is consistent with a phylogenetic reconstruction of the DUF39 family, which clearly distinguishes the CBS-associated and ferredoxin-associated DUF39s []. |
