Molecular oxygen regulates the enzymatic activity of a heme-containing diguanylate cyclase (HemDGC) for the synthesis of cyclic di-GMP.
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.
Sawai
Hitomi
H
Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Myodaiji, Okazaki, Aichi 444-8787, Japan.
Yoshioka
Shiro
S
Uchida
Takeshi
T
Hyodo
Mamoru
M
Hayakawa
Yoshihiro
Y
Ishimori
Koichiro
K
Aono
Shigetoshi
S
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
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