title: Molecular oxygen regulates the enzymatic activity of a heme-containing diguanylate cyclase (HemDGC) for the synthesis of cyclic di-GMP.
abstract: We have studied the structural and enzymatic properties of a diguanylate cyclase from an obligatory anaerobic bacterium Desulfotalea psychrophila, which consists of the N-terminal sensor domain and the C-terminal diguanylate cyclase domain. The sensor domain shows an amino acid sequence homology and spectroscopic properties similar to those of the sensor domains of the globin-coupled sensor proteins containing a protoheme. This heme-containing diguanylate cyclase catalyzes the formation of cyclic di-GMP from GTP only when the heme in the sensor domain binds molecular oxygen. When the heme is in the ferric, deoxy, CO-bound, or NO-bound forms, no enzymatic activity is observed. Resonance Raman spectroscopy reveals that Tyr55 forms a hydrogen bond with the heme-bound O(2), but not with CO. Instead, Gln81 interacts with the heme-bound CO. These differences of a hydrogen bonding network will play a crucial role for the selective O(2) sensing responsible for the regulation of the enzymatic activity.
authors.affiliation: Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Myodaiji, Okazaki, Aichi 444-8787, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Sawai
authors.forename: Shiro
authors.initials: S
authors.lastname: Yoshioka
authors.forename: Takeshi
authors.initials: T
authors.lastname: Uchida
authors.forename: Mamoru
authors.initials: M
authors.lastname: Hyodo
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Hayakawa
authors.forename: Koichiro
authors.initials: K
authors.lastname: Ishimori
authors.forename: Shigetoshi
authors.initials: S
authors.lastname: Aono
mesh_terms: D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000096:biosynthesis; D020564:Deltaproteobacteria / Q000201:enzymology; D029968:Escherichia coli Proteins; D006860:Hydrogen Bonding; D010100:Oxygen / Q000378:metabolism*; D019761:Phosphorus-Oxygen Lyases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D013059:Spectrum Analysis, Raman; D014443:Tyrosine / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D014443:Tyrosine; C062025:bis(3',5')-cyclic diguanylic acid; D019761:Phosphorus-Oxygen Lyases; C060720:diguanylate cyclase; D006152:Cyclic GMP; D010100:Oxygen