[ABSTRACT FROM AUTHOR]
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| Autor: |
Chauvatcharin, Nopmanee, Vattanaviboon, Paiboon, Switala, Jack, Loewen, Peter C., Mongkolsuk, Skorn |
| Předmět: |
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| Zdroj: |
Current Microbiology; Feb2003, Vol. 46 Issue 2, p0083-0087, 5p |
| Abstrakt: |
The first cloning and characterization of the gene katA, encoding the major catalase (KatA), from Xanthomonas is reported. A reverse genetic approach using a synthesized katA-specific DNA probe to screen a X. campestris pv. phaseoli genomic library was employed. A positively hybridizing clone designated pKat29 that contained a full-length katA was isolated. Analysis of the nucleotide sequence revealed an open reading frame of 1,521 bp encoding a 507-amino acid protein with a theoretical molecular mass of 56 kDa. The deduced amino acid sequence of KatA revealed 84% and 78% identity to CatF of Pseudomonas syringae and KatB of P. aeruginosa, respectively. Phylogenetic analysis places Xanthomonas katA in the clade I group of bacterial catalases. Unexpectedly, expression of katA in a heterologous Escherichia coli host resulted in a temperature-sensitive expression. The KatA enzyme was purified from an overproducing mutant of X. campestris and was characterized. It has apparent Km and Vmax values of 75 mM [H2O2] and 2.55 × 105 μmol H2O2 μmol heme-1 s-1, respectively. The enzyme is highly sensitive to 3-amino-1,2,4-triazole and NaN3, has a narrower optimal pH range than other catalases, and is more sensitive to heat inactivation. Correspondence to: S. Mongkolsuk, Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand; email: skorn@tubtim.cri.or.th --> [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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