Biophysical and biochemical studies of a major endoglucanase secreted by Xanthomonas campestris pv. campestris.

Author(s)

Rosseto, Flavio Rodolfo ; Manzine, Livia Regina ; Neto, Mario de Oliveira ; Polikarpov, Igor

• Document type: Journal article
• Source: Enzyme and Microbial Technology; v. 91, p. 1-7, SEP 2016.
• Web of Science Citations: 2

Abstract

Endoglucanases are the main cellulolytic enzymes secreted by the bacterium Xanthomonas campestris pv. campestris (Xcc). The major endoglucanase exported by this bacterium into an external milieu is an enzyme XccCel5A, which belongs to GH5 family subfamily 1 and is encoded by the gene engXCA. We purified XccCel5A using ammonium sulfate precipitation followed by size exclusion chromatography and identified it by zymogram analysis. Circular dichroism and fluorescence spectroscopy studies showed that XccCel5A is stable in a wide pH range and up to about 55 degrees C and denatures at the higher temperatures. The optimal conditions for enzyme activity were identified as T = 45 degrees C and pH = 7.0. Under the optimum conditions the catalytic efficiency (k(cat)/K-M) of the enzyme was determined as 5.16 x 10(4)s(-1) M-1 using carboxymethylcellulose (CMC) as a substrate. Our SAXS studies revealed extended tadpole-shape molecular assembly, typical for cellulases, and allowed to determine an overall shape of the enzyme and a relative position of the catalytic and cellulose binding domains. (C) 2016 Elsevier Inc. All rights reserved. (AU)

• FAPESP's process: 09/54035-4 - Facility for advanced studies of biosystems and nanostructured materials
• Grantee: Igor Polikarpov
• Support type: Multi-user Equipment Program
• FAPESP's process: 10/16542-9 - Studies of the cellulolytic enzymes with potential in the enzymatic transformation of the sugarcane biomass using Small Angle X-ray Scattering
• Grantee: Mario de Oliveira Neto
• Support type: Scholarships in Brazil - Post-Doctorate
• FAPESP's process: 10/08370-3 - Biophysical and biochemical studies of exoglucanases from Trichoderma harzianum involved in the biodegradation of cellulose
• Grantee: Wanius José Garcia da Silva
• Support type: Regular Research Grants
• FAPESP's process: 08/56255-9 - Structure and function of enzymes and auxiliary proteins from Trichoderma, active in cell-wall hydrolysis
• Grantee: Igor Polikarpov
• Support type: Program for Research on Bioenergy (BIOEN) - Thematic Grants