[Show abstract][Hide abstract] ABSTRACT: The aerobic hyperthermophilic archaeon Aeropyrum pernix expresses molybdopterin carbon monoxide dehydrogenase (Mo-CODH). A. pernix strains isolated from Tachibana Bay (TB1–8) were found to exhibit different levels of total Mo-CODH activity (low and high,
respectively), and the Mo-CODHs isolated from these strains also exhibit high or low activity. Mo-CODH gene transcription
was detected by real-time reverse transcription-PCR, but no relation was found between the expression level of mRNA and the
activity level of Mo-CODH. The nucleotide sequences of A. pernix genes encoding the small, large, and medium subunits of Mo-CODH, respectively, and those of the putative promoter region
were identified from all TB strains. Amino acid substitutions were found in the sequences of high- and low-activity strains,
but no mutation was detected in the putative promoter regions. Homology modeling revealed that all amino acid substitutions
were localized on the surface of the Mo-CODH proteins. Based on these findings, we conclude that in A. pernix, the activity level of Mo-CODH may be regulated by translation or post-translational modification rather than by genomic
diversity or transcription.
KeywordsCarbon monoxide dehydrogenase–Aerobe–Hyperthermophile–
No preview · Article · Jan 2011 · Fisheries Science
[Show abstract][Hide abstract] ABSTRACT: The aerobic hyperthermophilic archaeon Aeropyrum pernix expresses carbon monoxide (CO) oxidation activity under heterotrophic growth conditions. Using activity stain gel analysis,
CO oxidation activity was detected in a protein with a molecular mass of 210kDa. The 210kDa CODH protein was purified to
homogeneity from A. pernix. Aeropyrum Mo-CODH catalyzed the oxidation of CO with a specific activity of 2.1μmol CO min−1 mg−1 at 95°C, pH 8.0 using methyl viologen as the electron acceptor. The CODH protein showed high oxygen and thermo stability.
The protein contains three subunits: L (86.6kDa), M (34.5kDa), and S (12.6kDa), which form the LM2S complex. The molecular mass of the complex was calculated by gel filtration and found to be 163.7kDa. N-terminal amino
acid sequencing and peptide mass fingerprinting analysis of the subunits indicated that they corresponded to NP_148462.1,
NP_148464.2, and NP_148465.1, and their genes annotated the molybdo iron-sulfur flavoprotein carbon monoxide dehydrogenase
S, L, and M subunits, respectively. Phylogenetic analysis revealed that CODH belongs to a novel clade of diverse CODHs.
KeywordsAerobic-Hyperthermophilic-Crenarchaeota-Carbon monoxide dehydrogenase-Molybdopterin hydroxylase-
No preview · Article · Nov 2010 · Fisheries Science