Multiple chitinases of an endophytic Serratia proteamaculans 568 generate chitin oligomers

Abstract

Serratia proteamaculans 568 genome revealed the presence of four family 18 chitinases (. Sp ChiA, . Sp ChiB, . Sp ChiC, and . Sp ChiD). Heterologous expression and characterization of . Sp ChiA, . Sp ChiB, and . Sp ChiC showed that these enzymes were optimally active at pH 6.0-7.0, and 40. °C. The three . Sp chitinases displayed highest activity/binding to β-chitin and showed broad range of substrate specificities, and released dimer as major end product from oligomeric and polymeric substrates. Longer incubation was required for hydrolysis of trimer for the three . Sp chitinases. The three . Sp chitinases released up to tetramers from colloidal chitin substrate. . Sp ChiA and . Sp ChiB were processive chitinases, while . Sp ChiC was a non-processive chitinase. Based on the known structures of ChiA and ChiB from . S. marcescens, 3D models of . Sp ChiA and . Sp ChiB were generated. © 2012 Elsevier Ltd.