A Novel Manno-Oligosaccharide Binding Protein Identified in Alkaliphilic Bacillus sp. N16-5 Is Involved in Mannan Utilization.

Abstract

ManH, a novel substrate-binding protein of an ABC transporter, was identified from the mannan utilization gene cluster of Bacillus sp. N16-5. We cloned, overexpressed, and purified ManH and measured its binding affinity to different substrates by isothermal titration calorimetry. ManH binds to mannotriose, mannotetraose, mannopentose, and galactosyl-mannotriose with dissociation constants in the micromolar range. Deletion of manH led to decreased growth ability of the strain when cultivated in medium with manno-oligosaccharides or mannan as the carbon source. ManH belongs to a manno-oligosaccharide transporter and plays an important role in mannan utilization by Bacillus sp. N16-5.