title: Importance of specific hydrogen-bond donor-acceptor interactions for the key carbocycle-forming reaction catalyzed by 2-deoxy-scyllo-inosose synthase in the biosynthesis of 2-deoxystreptamine-containing aminocyclitol antibiotics.
abstract: A crucial enzyme in the biosynthesis of the 2-deoxystreptamine aglycon of clinically important aminocyclitol antibiotics is 2-deoxy-scyllo-inosose synthase (DOIS), which converts ubiquitous D-glucose 6-phosphate (G-6-P) into the specific carbocycle 2-deoxy-scyllo-inosose. Among all the oxygenated carbons of the substrate, C-1, -4, -5, and -6 are directly involved in the chemical transformation. To get insight into the roles of C-2 and C-3 hydroxy groups, 2-deoxy-2-fluoro-, 3-deoxy-3-fluoro-, 2-amino-2-deoxy-, and 3-amino-3-deoxy-D-glucose 6-phosphates (2-F-G-6-P, 3-F-G-6-P, 2-NH(2)-G-6-P, and 3-NH(2)-G-6-P, respectively) were subjected to the DOIS reaction as probe, since a fluorine substituent generally acts as a hydrogen-bond acceptor, and an ammonium functionality derived physiologically from an amino group as a hydrogen-bond donor. Among those tested, 2-F-G-6-P and 3-NH(2)-G-6-P were used as substrates by DOIS and were converted into the corresponding deoxyfluoro- and aminodeoxy-scyllo-inososes, respectively. In contrast, 3-F-G-6-P and 2-NH(2)-G-6-P were inactive in the cyclization reaction. Clearly, DOIS recognizes the G-6-P substrate through specific hydrogen-bonding interactions, i.e., through a hydrogen-donating group for C-2 and an accepting group for C-3 of the substrate. Modeling of DOIS based on the structure of evolutionary-related dehydroquinate synthase is also described.
authors.affiliation: Department of Chemistry and Materials Science, Tokyo Institute of Technology, O-okayama, Meguro-ku 152-8551, Japan. eguchi@cms.titech.ac.jp
authors.forename: Tadashi
authors.initials: T
authors.lastname: Eguchi
authors.forename: Satoko
authors.initials: S
authors.lastname: Sasaki
authors.forename: Zhen
authors.initials: Z
authors.lastname: Huang
authors.forename: Katsumi
authors.initials: K
authors.lastname: Kakinuma
mesh_terms: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000737:chemistry; D001407:Bacillus / Q000201:enzymology; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D003500:Cyclization; D004926:Escherichia coli / Q000201:enzymology; D019298:Glucose-6-Phosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D006595:Hexosamines / Q000096:biosynthesis; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D007294:Inositol / Q000031:analogs & derivatives*; D007700:Kinetics; D008190:Lyases / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013379:Substrate Specificity
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D006595:Hexosamines; C002183:inosose; D007294:Inositol; D019298:Glucose-6-Phosphate; D008190:Lyases; C085631:2-deoxy-scyllo-inosose synthase