A highly active phosphoglucomutase from Clostridium thermocellum: cloning, purification, characterization and enhanced thermostability.
J Appl Microbiol
; 108(1): 39-46, 2010 Jan.
Article
em En
| MEDLINE
| ID: mdl-19566723
ABSTRACT
AIMS:
Discovery and utilization of highly active and thermostable phosphoglucomutase (PGM) would be vital for biocatalysis mediated by multiple enzymes, for example, high-yield production of enzymatic hydrogen. METHODS ANDRESULTS:
The thermophilic cellulolytic bacterium Clostridium thermocellum was hypothesized to have a very active PGM because of its key role in microbial cellulose utilization. The Cl. thermocellum ORF Cthe1265 encoding a putative PGM was cloned and expressed in Escherichia coli. The purified enzyme appeared to be a monomer with an estimated molecular weight of 64.9 kDa. This enzyme was found to be a dual-specificity enzyme - PGM/phosphomannomutase (PMM). Mg(2+) and Mn(2+) were activators. Ser144 was identified as an essential catalytic residue through site-directed mutagenesis. The k(cat) and K(m) of PGM were 190 s(-1) and 0.41 mmol l(-1) on glucose-1-phosphate and 59 s(-1) and 0.44 mmol l(-1) on mannose-1-phosphate, respectively, at 60 degrees C. Thermostability of PGM at a low concentration (2 nmol l(-1), 100 U l(-1)) was enhanced by 12-fold (i.e. t(1/2) = 72 h) at 60 degrees C with addition of bovine serum albumin, Triton X-100, Mg(2+)and Mn(2+).CONCLUSIONS:
The ORF Cthe1265 was confirmed to encode a PGM with PMM activity. This enzyme was the most active PGM reported. SIGNIFICANCE AND IMPACT OF THE STUDY This highly active PGM with enhanced thermostability would be an important building block for in vitro synthetic biology projects (complicated biotransformation mediated by multiple enzymes in one pot).
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Base de dados:
MEDLINE
Assunto principal:
Fosfoglucomutase
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Proteínas de Bactérias
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Proteínas Recombinantes
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Clostridium thermocellum
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article