The cdhABC genes encoding the respective α, ε, and β subunits of the five-subunit (α, β, γ, δ, and ε) CO dehydrogenase/acetyl-coenzyme synthase (CODH/ACS) complex from Methanosarcina thermophila were cloned and sequenced. Northern (RNA) blot analyses indicated that the cdh genes encoding the five subunits and an open reading frame (ORF1) with unknown function are cotranscribed during growth on acetate. Northern blot and primer extension analyses suggested that mRNA processing and multiple promoters may be involved in cdh transcript synthesis. The putative CdhA (α subunit) and CdhB (ε subunit) proteins each have 40% identity to CdhA and CdhB of the CODH/ACS complex from Methanosaeta soehngenii. The cdhC gene encodes the subunit (CdhC) of the CODH/ACS complex from M. thermophila. The N-terminal 397 amino acids of CdhC are 42% identical to the C-terminal half of the α subunit of CODH/ACS from the acetogenic anaerobe Clostridium thermoaceticum. Sequence analysis suggested potential structures and functions for the previously uncharacterized β subunit from M. thermophila. The deduced protein sequence of ORF1, located between the cdhC and cdhD genes, has 29% identity to NifH2 from Methanobacterium ivanovii.
All Science Journal Classification (ASJC) codes
- Molecular Biology