A novel chimera: the "truncated hemoglobin-antibiotic monooxygenase" from Streptomyces avermitilis.
Novel chimeric proteins made of a globin domain fused with a "cofactor free" monooxygenase domain have been identified within the Streptomyces avermitilis and Frankia sp. genomes by means of bioinformatics methods. Structure based sequence alignments show that the globin domains of both proteins can be unambiguously assigned to the truncated hemoglobin family, in view of the striking similarity to the truncated hemoglobins from Mycobacterium tuberculosis, Thermobifida fusca and Bacillus subtilis. In turn, the non-heme domains belong to a family of small (about 100 aminoacids) homodimeric proteins annotated as antibiotic biosynthesis monooxygenases, despite the lack of a cofactor (e.g., a metal, a flavin or a heme) necessary for oxygen activation. The chimeric protein from S. avermitilis has been cloned, expressed and characterized. The protein is a stable dimer in solution based on analytical ultracentrifugation experiments. The heme ligand binding properties with oxygen and carbonmonoxide resemble those of other Group II truncated hemoglobins. In addition, an oxygen dependent redox activity has been demonstrated towards easily oxidizable substrates such as menadiol and p-aminophenol. These findings suggest novel functional roles of truncated hemoglobins, which might represent a vast class of multipurpose oxygen activating/scavenging proteins whose catalytic action is mediated by the interaction with cofactor free monooxygenases.
Bonamore
Alessandra
A
Department of Biochemical Sciences, University of Rome La Sapienza, P.le Aldo Moro 5, 00185 Rome, Italy.
Attili
Andrea
A
Arenghi
Fabio
F
Catacchio
Bruno
B
Chiancone
Emilia
E
Morea
Veronica
V
Boffi
Alberto
A
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002248:Carbon Monoxide / Q000378:metabolism; D019281:Dimerization; D006420:Hemeproteins / Q000235:genetics*; D007700:Kinetics; D006899:Mixed Function Oxygenases / Q000235:genetics*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013056:Spectrophotometry, Ultraviolet; D013302:Streptomyces / Q000235:genetics* / Q000378:metabolism
D001426:Bacterial Proteins; D006420:Hemeproteins; D011993:Recombinant Fusion Proteins; D002248:Carbon Monoxide; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases; C020094:duroquinol oxidase; D010100:Oxygen