A previously unrecognized kanosamine biosynthesis pathway in Bacillus subtilis.

Area of Science:

• Microbiology
• Biochemistry
• Enzymology

Background:

• The ntd operon in Bacillus subtilis is crucial for synthesizing 3,3'-neotrehalosadiamine (NTD), a disaccharide with antibiotic properties.
• The specific functions of the enzymes NtdA, NtdB, and NtdC within this operon were previously uncharacterized in vitro.

Purpose of the Study:

• To elucidate the in vitro enzymatic functions of NtdA, NtdB, and NtdC from Bacillus subtilis.
• To characterize the novel pathway for kanosamine biosynthesis in Bacillus subtilis.

Main Methods:

• Enzymatic assays were performed to determine the catalytic activities of purified NtdA, NtdB, and NtdC.
• Substrate specificity and reaction products were analyzed to define the biochemical pathway.

Main Results:

• NtdC was identified as a glucose-6-phosphate 3-dehydrogenase.
• NtdA functions as a pyridoxal phosphate-dependent 3-oxo-glucose-6-phosphate:glutamate aminotransferase.
• NtdB acts as a kanosamine-6-phosphate phosphatase, completing the kanosamine biosynthesis pathway from glucose-6-phosphate.

Conclusions:

• The study demonstrates a novel enzymatic pathway for kanosamine biosynthesis in Bacillus subtilis, catalyzed by NtdA, NtdB, and NtdC.
• This pathway represents an alternative route to kanosamine production compared to the UDP-glucose-dependent pathway found in Amycolatopsis mediterranei.
• The findings provide new insights into the biosynthesis of unusual sugars with potential antibiotic applications.