Microbial Deglycosylation of Plant Metabolites: A Case Study with Actinoplanes missouriensis 431T

Abstract

Actinoplanes missouriensis 431T(=NRRL B-3342) is a soil isolate, well known for its ability to degrade flavonoids. In this work, we identified an intracellular α-l-rhamnosidase from A. missouriensis 431Tin the genomic vicinity of the previously reported diglycosidase 6-O-α-l-rhamnosyl-β-d-glucosidase (αRβG). The α-l-rhamnosidase (BAL86047.1) was functionally expressed in Escherichia coli. The purified protein (94 kDa) was able to hydrolyze rutinose to the corresponding monosaccharides. The highest activity was found at 40 °C and pH 6 in sodium citrate buffer. Regarding substrate specificity, a preference for rutinose and 7-O-diglycosylated flavanones was observed, and only traces of activity (<5%) were detected with 3-O-rutinosyl flavanols. Minor activity was found with karaya, arabic, and gellan gums. The α-l-rhamnosidase and the αRβG were associated with a pattern of genes possibly involved in the degradation and intake of the glycosidic fraction of 7-O-rutinosylated flavanones. This gene pattern was also found in five related Actinoplanes strains.